Horticulture

Agricultural producers in California received $586 million in federal assistance in 2001; Of this about $242 million came as production flexibility contracts and loan deficiency payments.The remainder of government payments to farmers came in the form of marketing support and conservation payments, which we discuss later in this chapter. While these federal government support payments are low in total compared to those states where the major agricultural products are grains or oil seeds, this does not imply that some agricultural producers in California do not benefit greatly from subsidies and protectionist measures.Over 100 farms in California received more than $425,000 each in subsidies in 2001 . Dairy, sugar and cattle producers receive significant protection from import barriers, and many producers receive subsidized inputs, particularly irrigation water. Sumner and Hart estimated the Producer Subsidy Equivalent paid to California agriculture in 1995 , where the PSE is defined as all government transfers to the industry including but not limited to production subsidies. They calculate that the California agricultural sector receives annual PSE transfers of $2.3 billion per year or about 11 percent of total commodity receipts. This is about one-half of the percentage PSE for all U.S. agriculture at the time,fodder sprouting system mainly because fruits and vegetables receive fewer transfers than the average commodity.

However, California’s PSE is higher than the percentage PSE received by producers in liberalized markets like Australia and New Zealand where the 1995 PSE was about 3 percent. While the specific estimates of PSE vary over time, the general pattern identified by Sumner and Hart, that California producers have a lower PSE than the U.S. national average but higher than that for other agricultural exporters, holds today.The formation of the Canada-United States Free Trade Agreement in 1989 and the North American Free Trade Agreement in 1994, has led to greatly expanded agricultural trade between Canada, California’s top market, and the U.S. NAFTA was designed to integrate economic activity among three nations: Canada, the U.S. and Mexico. It serves as a free trade agreement rather than a customs union or common market. Since 1989, U.S. agricultural exports to Canada have expanded by about 3 and one-half times, from $2.24 billion to $7.65 billion. Over the same period, agricultural imports from Canada have risen almost three-fold, from $2.93 billion to $8.66 billion. Fruits and vegetables account for more than one-third of Canada’s agricultural imports from the U.S., so California plays an important role in this north south trade. However, in spite of the CUSTA and NAFTA, Canada continues to intervene in agricultural trade flows. The country uses non-tariff barriers such as licenses that restrict imports of bulk produce, fresh fruits, vegetables, and wine. For instance, Canadian regulations on fresh fruit and vegetable imports prohibit consignment sales of fresh fruit and vegetables without a prearranged buyer . Canada also severely limits imports of dairy products, eggs, and poultry.

According to the WTO Appellate Body, Canada’s supply management system for dairy provides implicit export subsidies for these products . Producer groups in the U.S. have called for the greater use of non-tariff barriers to limit agricultural imports from Canada. This has often been accomplished by the use of U.S. trade remedy laws. Trade remedy laws are intended to offset “unfair” trade that injures domestic producers as a result of either foreign sales that are “dumped” into the U.S. at less than fair value or influenced by foreign government subsidies. The regular use of trade remedy laws within NAFTA illustrates the fact that any transition to freer trade in agriculture, even between countries at relatively similar stages of development, may be politically difficult. An example of the agricultural trade tensions between Canada and the U.S. is the recent “tomato wars,” in which U.S. producers accused the Canadians of “dumping” tomatoes in the U.S. market. In October 2001, the United States government made a preliminary ruling that Canadian growers were dumping greenhouse tomatoes into the United States at prices below the Canadian cost of production. As a result of this finding, Canadian sales into the United States were assessed an average tariff of 32 percent. Several weeks later, the legal tables were turned as the Canadian government initiated an anti-dumping investigation against the U.S. fresh tomato industry . The Canadian counterclaim may not have been a coincidence. Rather, it may have been a tit-for-tat reaction to the steep U.S. duties imposed on Canadian greenhouse tomato sales to the United States. By July 2002, both cases were resolved with identical rulings of no material injury.

While U.S. exports of fresh tomatoes to Canada declined 10 percent over the previous year during the period of investigation, Canadian imports of greenhouse tomatoes to the United States actually increased 17 percent over that year .Despite the fact that Japanese agriculture receives high levels of government support and has limited market orientation , it is also the world’s largest net importer of agricultural products. The United States supplies roughly one-third of Japan’s agricultural imports, and in 2002, Japan’s agricultural imports from the U.S. were valued at $8.3 billion . About 20 percent of these U.S. exports to Japan originated in California. Japan is California’s third largest export market for agricultural products, with rice, cotton, almonds, beef, and oranges ranking as the top commodities . Japan’s weak economy has dampened its total agricultural imports in recent years . In the 1990s, the most significant import growth in Japan was in the area of fruits and vegetables, wine, and beef . More recently, grains and oil seeds have done better . Japan continues to restrict imports of horticultural products, livestock products, and processed foods, all of which are important exports for California. Recently, beef exports to Japan were halted in response to the BSE scare in Europe; and Japan continues to consider implementing a “beef import safeguard,” which could further lower imports even further. At the time of this writing, Japan had halted all imports of U.S. beef, due to the discovery of BSE in the U.S. . Citing phytosanitary concerns, Japan blocks imports of U.S. fresh fruit, vegetables, and other horticultural crops, keeping Japanese domestic prices of horticultural products artificially high. Government subsidies are also provided to farmers to encourage them to divert land out of rice production and into vegetables . Japan also has country-of-origin labeling requirements for agricultural products that principally affect fruits, vegetables and animal products . This acts as a non-tariff barrier to trade. Japan maintains high tariffs on beef, citrus, and processed foods. In addition, imported high quality California rice is strictly controlled and rarely reaches the consumer food table in Japan. The over quota rice tariff in Japan exceeds 400 percent. Until recently, Japan’s system of food imports used mainly non-tariff barriers such as quotas and licenses, instead of tariffs. Sazanami et al. found that Japan’s tariffs on food imports averaged only 8 percent, but the quantitative import barriers averaged 272 percent, with the rice tariff equivalent barrier at 737 percent. Despite the tariffication required by the Uruguay round of trade liberalization, of Japan’s agricultural imports remain highly protected . In addition, Japan continues to use health and safety regulations to serve as barriers to trade.3 In the case of fresh oranges and lemons, the U.S. is the largest supplier to Japan,microgreen fodder system accounting for over 80 percent of Japan’s imports. Other exporters of oranges and lemons of lesser importance in Japan are Australia, Chile, and South Africa. The Japanese Government continues to impose a high import tariff on fresh oranges. The tariff rate is 32 percent for imports during the December-May period, and 16 percent during June-November. .California’s second most important market, the EU, provides export subsidies for beef, cheese, other dairy products, and processed fruit, in competition with California. It also provides generous production subsidies on horticultural products such as tomatoes, grapes, peaches and lemons. The EU’s subsidized production of these products affects California’s competitiveness in third markets.

More generally, the EU’s Common Agricultural Policy significantly isolates European farmers from international competition. The CAP is a system of subsidies and market barriers that include mandatory land set-asides, commodity specific direct payments, and export subsidies . Support to agricultural producers as a share of total agriculture receipts is 40 percent higher in the EU than in the U.S. . Much of this support comes in the form of higher prices paid by domestic consumers. Recently, there has been increasing pressure to significantly reform the CAP; the program has been called by the popular press an “extravagant folly” and “demented” . These publications and others have argued that reform of the CAP will be a critical element of the next round of trade negotiations, if these talks are to be successful. Enlargement of the EU to include ten Central and Eastern European countries will also create pressure for further reform. Structural reforms of European agricultural policy will have important implications for California, both because the region competes in third markets with California, and because the region is an important customer, as discussed earlier. If the existing EU agricultural policy is applied to the 10 new member countries, the incentive will be to increase production and agricultural exports. Several of the new member countries have a comparative advantage in agriculture, especially in the area of wheat, coarse grains, and livestock. California agriculture will benefit if this expanded production results in budgetary pressure to reform the CAP. In addition, California agriculture may well benefit from projected income growth in Central and Eastern Europe that results from EU membership. Higher incomes in this region will lead to increased demand there for high-valued food, of the type exported from California. An ongoing trade dispute between the US and the EU concerns the use of geographical indicators . The EU wants to prohibit foreign producers of food and beverage products from labeling products with European regional names . The list of products that will receive this protection is an on-going subject of negotiation at the WTO. For California there is a trade-off associated with GI protection. On the one hand, California would have to stop using certain names if the EU is successful . On the other hand, California agriculture could use GI protection to develop niche markets for its food and beverage products, potentially capturing a price premium.China is a relatively new member of the WTO, and developments in China’s agricultural trade are being carefully watched by the California industry. China’s land area sown to fruits, nuts, and vegetables has grown rapidly in the past decade, and trade is expected to take on a greater importance for China in coming years now that it has joined the WTO. China’s horticultural exports account for more than one-half of its agricultural exports . Given China’s rich agricultural resources, abundant labor supply, and large population, it has great potential to play a much more prominent role in agricultural trade in the coming years, as both an exporter and an importer. China uses both tariff and non-tariff barriers to restrict agricultural imports. China has in place high import tariffs on certain agricultural commodities currently exported by California, such as citrus, table grapes, wine, beef and dairy products. There is also evidence that the value added tax in China, as currently applied, results in a price break for domestic field crops as compared to imports, of about 4 percent . China has import tariffs on citrus and table grapes of approximately 10 percent and maintains a restrictive tariff rate quota on cotton. As part of its WTO accession negotiations, China agreed to a significant lowering of these tariffs to around 10 to 12 percent. In addition, if the WTO liberalizes world trade in clothing and textiles , then China will undoubtedly expand exports of clothing and textiles. This could result in increased imports of cotton into China. Domestic developments in China not directly related to trade policy but related to rising incomes may also present opportunities for California agricultural exports to that country. For example, both the USDA Foreign Agricultural Service and the popular press have recently highlighted the growing importance of western-style supermarkets in Chinese cities, replacing more traditional markets. This may present a new opportunity for California producers, with new opportunities to supply pre-packaged or processed products and products that require refrigeration.

Fruits,tree-nuts, and vegetables represent about half of these totals, while dairy and poultry products, and grains are also major contributors.In 1998, fresh and processed fruits, tree-nuts, and vegetables had the greatest impact of any commodity group on California’s economy, generating about half the direct and indirect sales, total income, value added and jobs related to agriculture. About one third of the $33 billion in direct sales in this category was attributable to sales of alcoholic and non-alcoholic beverages. Examples of beverages linked to fruit, tree-nut and vegetable production include wine and juice. Some of the beverages included in this category may reflect processing of grain products rather than fruit, tree-nuts and vegetables. Dairy and poultry products and grains also had significant economic contributions, accounting for between 10 percent and 20 percent of the total income, value added, and jobs related to agriculture.Because of its climatic advantages, California is able to produce a great variety of products that are not grown extensively elsewhere in the United States. The California Department of Food and Agriculture estimates that the state is the leading U.S. producer for about 65 crop and livestock commodities.

Fifty-five percent of the value of California agriculture’s $26.1 billion in 2002 farm gate sales is contributed by the fruit , vegetable , and nut industries. Indeed, California dominates the U.S. horticultural sector, accounting for approximately 37, 55 and 85 percent, respectively, of the 2002 farm gate value of the principal vegetables, fruit, and tree nuts produced in the United States . California’s leading position in the $30.8 billion U.S. horticultural industry is explained by climatic, technological, and infrastructure advantages, as well as the market- and consumer-driven orientation of its agribusiness managers. Given the importance of horticultural crops to California agriculture,dutch bucket hydroponic and to the nation, our discussion draws heavily on examples from this sector.Many of California’s fruits and vegetables are highly perishable, and production is seasonal. A major challenge in marketing is to ensure both the high quality of these products and their availability to consumers year-round. Another key challenge facing marketers is the maturity of the U.S. market. Both the U.S. population growth rate and the income elasticity of demand for food are low, meaning that the market for domestic food consumption expands only slowly over time, and firms are essentially competing for share of stomach. This competition has intensified given the high rate of new product introductions and expanded year-round availability of formerly seasonal items, often through imports. Both of these factors have led to a greater array of substitute products, frequently dampening demand for large-volume staples like oranges and apples.

California’s bounty also presents opportunities. Through the diversity of its agricultural production, firms marketing California produce have the opportunity to provide food retailers with complete lines of fruits, vegetables, and nuts. Because California produces a large share of the U.S. supply of key commodities such as almonds, lemons, olives, lettuce, prunes, strawberries, table grapes, processing tomatoes, and walnuts, California producers and marketers traditionally had unique opportunities to exercise control over the markets for those commodities. However, expanding world supply of many commodities has reduced California’s share, increasing competition and presenting new marketing challenges. This chapter documents the importance of marketing in both U.S. and California agriculture and highlights the institutions that have emerged and the strategies that have been pursued by California’s food marketing sector to compete effectively in this market environment.The U.S. food industry is the largest in the world. The final value of food sold through all retail channels was $485.2 billion in 2002 with an additional $415 billion sold through foodservice channels . Marketing functions account for the largest share of the U.S. food dollar, and the percentage of food costs due to marketing is rising over time. Food marketing thus has an important effect on the welfare of both consumers and farmers. The U.S. Department of Agriculture maintains two general measures of relative food costs. The market basket consists of the average quantities of food that mainly originate on U.S. farms and are purchased for consumption at home.

The farm share of the value of the market basket remained stable at about 40 percent from 1960- 80 but has declined rapidly since then, to 30 percent in 1990 and 21 percent in 2001. Table 1 depicts the trend in farm share for selected commodities of importance to California. Although farm value has traditionally accounted for more than 50 percent of retail value for animal products such as meat, dairy, poultry, and eggs, those shares have now fallen well below half. The farm share for fruits and vegetables tends to be much lower and does not differ much between fresh and processed fruits and vegetables.The second major measure of food marketing costs in the U.S. is the marketing bill, which is calculated as the difference between what consumers spend for domestically produced farm foods and what farmers receive. In 2001 the farm share of the food marketing bill was 19 percent. This measure of the farm share has also been declining steadily over time, falling from 41 percent in 1950 to 31 percent in 1980 and then to 24 percent in 1990. The marketing bill takes account of food expenditures both at home and in restaurants. The proportion of the U.S. food dollar spent outside the home has been rising rapidly. In 2002, such expenditures accounted for 46 percent of the food budget compared to 37 percent in 1990 and 32 percent in 1980.While the overall U.S. food market is characterized by slow growth, eating habits are becoming more diverse. Demographic and psychographic trends, such as ethnic diversity and new attitudes about food consumption as it relates to self-identity and well-being, have contributed to a much more segmented market. Food marketers must increasingly target specific consumer segments rather than employing mass marketing strategies. More retailers are looking to their suppliers to assist them in understanding and better serving different types of consumer segments. In response, many suppliers are becoming involved in new types of marketing services, including consumer research and category management. The latter is designed to help retailers improve net profitability for a category of products through efficient assortment, pricing, promotion and shelf-space management. For suppliers the aim is to focus on identifying and servicing the evolving needs of specific accounts as a preferred supplier, rather than marketing more homogeneous products with fewer support services on a spot market basis. The U.S. retail industry is dominated by chain stores. In 2002,dutch buckets system retail chains accounted for 83 percent of supermarket industry sales vs. 58 percent in 1954 . The remainder of sales is by independent stores, although the vast majority of these stores are affiliated to buying groups, either voluntary chains such as Supervalu or to a lesser extent retailer cooperatives such as Associated Wholesale Grocers. In 2002 there were 32,981 supermarkets including all format types. Firms in the U.S. food-marketing sector often view a large market share, including, if possible, the position of market leader, as a key requisite to success. Pursuit of market share has led to a dramatic consolidation in the U.S. food chain at all levels, ranging from the farm through food retailing.

Due to the difficulty of capturing sizable market share from rival firms, many U.S. food marketers have pursued share growth through mergers and acquisition of rivals. Mergers and acquisitions in the food sector occurred at a rapid pace in the 1980s, temporarily peaked in 1988 at 573 mergers, declined and then reached an all-time high of 813 in 1998, since declining to 415 in 2003 . Although the growth in merger activity has temporarily abated, cumulative activity in recent decades has likely had important implications for the structure of competition in the U.S. food sector. Consolidation occurring at the food manufacturing level has progressed rapidly for some time. About 16,000 food and tobacco processing companies operate in the U.S., but in 1997 about 75 percent of sales were by the 100 largest of these firms. The largest sales growth, fueled mostly by mergers and acquisitions, has been recorded by the top 20 of these 100 firms, which in 1997 were estimated to account for about 50 percent of value added in food manufacturing . Most of the 53 food and tobacco industries surveyed in the U.S. Census of Manufacturing have experienced increasing concentration over time. The average market share held by the four largest firms in these industries has risen from 43.9 percent in 1967 to 53.3 percent in 1992, the most recent year for which data are available. In contrast to the food manufacturing sector, over the decade 1987-97 retail concentration ratios were quite stable with the share of U.S. food sales accounted for by the top 4, 8 and 20 retailers at about 20, 30, and 40 percent, respectively. During this decade new players were emerging in the U.S. food system, including value oriented retailers such as Wal-Mart with its fast expanding super center and club store formats, specialty food retailers like Trader Joe’s, European entrants into U.S. food retailing, and other mass and drug store merchandisers entering the food business. This phenomenon is called channel blurring and continues with the recent emergence of “Dollar Stores,” on-line food shopping and the on-going competition from the food service sector for the consumer food dollar. This challenging marketplace motivated many conventional retailers to become larger in hopes of improving their competitiveness. From 1997-1999, in particular, mergers occurred between several already large retail chains, beginning to induce important and still unfolding changes in relationships between buyers and suppliers. By 2002 the estimated share of U.S. food sales accounted for by the top 4, 8 and 20 retailers had reached 31, 45, and 57 percent, respectively. This means that in 2002 suppliers faced a market where only 20 retail firms sold at least $276 billion in food. Despite the mergers, the United States has no truly national supermarket chains. In 2002 only eight chains had over 1,000 stores, and only one of these has over 2,000 outlets. Given the large geographic size of the United States, chains tend to be regional in focus. However, the recent high merger activity has contributed to much larger chains than ever before, with five surpassing $25 billion in sales in 2002, and four with stores in over half of the country. Still, many local and regional chains remain quite competitive by staying in close contact with their customers and implementing highly targeted marketing strategies. The regional, ethnic and demographic diversity of U.S. consumers leads some to predict that small to mid-size chains may have an important role to play for some time to come. Within the retail channel the super center concept has emerged as a major industry force, which further concentrates buying power in the hands of a few very large new players. Super centers are a type of mass merchandising format combining a full-line supermarket with a full-line discount department store and range up to 24,400 square meters in size , compared to 4,900 square meters for the average supermarket. Total 2002 grocery-equivalent sales of super centers were estimated at $45.5 to $50.3 billion with total super center sales reaching $116.7 billion . The largest entrant to this format is Wal-Mart, with an estimated $29.3 billion in U.S. grocery-equivalent 2002 food sales, a 75 percent share of national super center sales and 1,333 super centers as of mid-2003. Already the largest retailer in the world, operating in ten countries, Wal-Mart is opening over 200 new super centers per year in the U.S. alone, and is fast becoming the dominant global player in grocery retailing with $244.5 billion in 2002 global sales among all its store formats, including large discount stores and warehouse club stores . Wal-Mart has also entered the conventional grocery-retailing sector in the U.S. with 52 neighborhood markets in 2002, and growing. Wal-Mart’s immense buying power combined with its approach of driving non value-adding costs out of the food system appears to have raised the competitive benchmark for conventional retailers. It emphasizes supply chain management via covendor managed automatic inventory replenishment procurement systems.

For these reasons California became the only substantial market for the header technology. The header technology evolved in an entirely different direction from the reaper, leading directly to the development in California of a commercial combined harvester. From the starting point of the header, it was quite simple and natural to add a thresher pulled along its side. There had been numerous attempts in the East and Midwest to perfect a machine that reaped and threshed in one operation. Among those that came closest to succeeding was Hiram Moore’s combine built in Kalamazoo, Michigan, in 1835. But in the humid Midwest, combining suffered from the same problems with moisture that had plagued heading. In 1853 Moore’s invention was given new life when a model was sent to California, where it served as a prototype for combine development.35 After several decades of experimentation in California, workable designs were available by the mid-1880s and the period of large-scale production and adoption began. Most of the innovating firms, including the two leading enterprises—the Stockton Combined Harvester and Agricultural Works and the Holt Company—were located in Stockton. During the harvest of 1880 “comparatively few” machines operated in California,planting gutter and agricultural authorities, such as Brewer and Hilgard, clearly suggest that even those machines should be considered as experimental. In 1881 about 20 combines were under construction in Stockton.By 1888, between 500 and 600 were in use.

The first truly popular model was the Houser, built by the Stockton Combined Harvester and Agricultural Works. In 1889, its advertisements claimed that there were 500 Houser machines in use, and that they outnumbered all of the competitors put together. Soon thereafter, machines in the Holt line overtook the Houser. The innovative products of the Holt company, which included in 1893 the first successful hillside combine, became dominant on the West Coast. By 1915 Holt’s advertisements boasted that over 90 percent of California’s wheat crop was harvested by the 3,000 Holt combines in the state.It is important to recognize that the adoption of combine-harvesters east of the Rockies was only in its infancy at this date. Combine models that eventually were adopted in the Midwest and Great Plains were considerably smaller than West Coast machines. The primary reasons for the differences were undoubtedly cost and scale considerations, but the prejudice in the East that large teams of horses were unworkable and the lack of practice probably played important roles.In California the opposite attitudes were said to prevail. The Pacific Rural Press boasted “f one man could drive all the mules in the State it would be the acme from one point of view.”California farmers had gradually developed their ability to manage large teams as a result of their experience with gang plows and headers.The difficulties associated with controlling large teams induced Holt and others to perfect huge steam tractors to pull their even larger harvesters. While steam-driven combines never came into vogue, these innovative efforts did have one highly important by-product—the track-laying tractor. The first practical track-laying farm tractors were initially developed to operate on the soft soil of the Sacramento-San Joaquin Delta.Although the crawlers were first designed to solve a local problem, this innovation was of global significance.

The Caterpillar Tractor Company would build larger, more powerful equipment that rapidly spread throughout the world. The reoccurring pattern of one invention creating new needs and opportunities that led to yet another invention offers important lessons for understanding the lack of development in other times and places. The key to explaining the progression of innovations in California was the close link between manufacturers and farmers that facilitated constant feedback between the two groups and the keen competition among producers that spurred inventive activity. Entrepreneurs seeking their fortunes were in close tune with their potential customers’ needs and vied with one another to perfect equipment that would satisfy those needs. Where these forces were not at work, the burdens of history severed the potential backward linkages that are so critical for economic development.Just as there were major investments in mechanical technologies to increase the productivity of labor, there were also substantial investments to increase the productivity of California’s land. These included agro-chemical research, biological learning concerning appropriate crops and cultural practices, and land clearing and preparation, but the most notable were investments in water control and provision. These took two related forms.In this realm, Californians literally re-shaped their landscape as individual farms leveled the fields and constructed thousands of miles of ditches. In addition, individual farms, reclamation districts, and the Army Corps of Engineers built several thousand miles of major levees to tame the state’s inland waterways. The second form consisted of a variety of measures to supply the state’s farms with irrigation water. Table 1 details the growth in the state’s irrigated acreage between 1890 and 1997. Expansion occurred in two main waves: the first lasting from 1900 through the 1920s and the second, linked to the Central Valley Project, during the decade after World War II.

Much of the historical growth of irrigation was the result of small-scale private initiatives rather than large-scale public projects that have attracted so much scholarly attention. Up until the 1960s, individuals and partnerships were the leading forms of organization supplying irrigation water. These forms accounted for roughly one-third of irrigated acres between 1910 and 1930, and over one-half by 1950. These small-scale irrigation efforts were closely associated with the rising use of groundwater in California over the first half of the twentieth century. Between 1902 and 1950, the acreage irrigated by groundwater sources increased more than thirty fold, whereas that watered by surface sources only tripled. Groundwater, which had supplied less than 10 percent of irrigated acreage in 1902, accounted for over 50 percent of the acreage by 1950. This great expansion was reflected in the growing stock of pumping equipment in the state. Underlying this growth were significant technological changes in pumping technology and declining power costs. During the 1910s and 1920s, the number of pumps, pumping plants, and pumped wells doubled each decade, rising from roughly 10,000 units in 1910 to just below 50,000 units in 1930. Pumping capacity increased two-and-one-half to three times per decade over this period. Expansion stalled during the Great Depression, but resumed in the 1940s with the number of pumps, plants, and wells rising to roughly 75,000 units by 1950. Individuals and partnerships dominated pumping, accounting for about 95 percent of total units and approximately 80 percent of capacity over the 1920-50 period.Since the 1950s, there has been a shift away from individuals and partnerships, as well as groundwater sources. By the 1970s, irrigation districts—public corporations run by local landowners and empowered to tax and issue bonds to purchase or construct, maintain,gutter berries and operate irrigation works—had become the leading suppliers. The district organization rapidly rose in importance over two periods. In the first, lasting from 1910 to 1930, acreage supplied by irrigation districts increased from one in-fifteen to approximately one-in-three. Much of this growth came at the expense of cooperative and commercial irrigation enterprises. Between 1930 and 1960, the district share changed little. During the 1960s, the district form experienced a second surge in growth, which was due in part to the rising importance of large-scale federal and state projects, which distributed water through these organizations. By 1969, irrigation districts supplied more than 55 percent of all irrigated acreage.Few issues have invoked more controversy in California than recurrent problems associated with agricultural labor. Steinbeck’s portrayal of the clash of cultures in The Grapes of Wrath represents the tip of a very large iceberg. The Chinese Exclusion Act, the Gentlemen’s Agreement aimed at Japanese immigrants, the repatriation of Mexicans during the Great Depression, the Great Cotton Strikes of 1933, 1938, and 1939, the Bracero Program of the 1940s, ‘50s, and ‘60s, the UFW and Teamsters organizing campaigns and national boycotts, the state’s Agricultural Relations Act, the legal controversy over the mechanization of the tomato harvest, and the current battles over illegal immigration are all part of a reoccurring pattern of turmoil deeply rooted in California’s agricultural labor market. There are few if any parallels in other northern states; clearly, the history of agricultural labor in California is very different. For all the controversy, however, the state’s farms have remained a beacon attracting large voluntary movements of workers seeking opportunity. Chinese, Japanese, Sikhs, Filipinos, Southern Europeans, Mexicans, Okies, and then Mexicans again have all taken a turn in California’s fields. Each group has its own story, but in the space allotted here we attempt to provide an aggregate perspective on some of the distinguishing characteristics of California’s volatile agricultural labor market. The essential characteristics of today’s labor market date back to the beginning of the American period. Table 2 offers a view of the role of hired labor in California compared to the nation as a whole.

Expenditures on hired labor relative to farm production and sales have generally been two-to-three times higher in California than for the United States. Within California the trend shows some decline. Another important perspective is to assess the importance of agricultural employment in the economy’s total labor force. Here the evidence is somewhat surprising.Both agriculture and agricultural labor play a relatively prominent role in most renderings of the state’s history. But as Table 2 indicates, until the last two decades, agricultural employment in California has generally been less important to the state than for the country. Clearly, it is the special nature of the state’s labor institutions, not their overall importance in the economy, that warrants our attention. From the beginning of the American period, California farms have relied more extensively on hired labor than their counterparts in the East. At the same time Californians never developed the institutions of slavery or widespread share-cropping as did their counterparts in the South. The parade of migrants who have toiled in California’s fields has often been described as “cheap labor.” But this appellation is something of a misnomer, because the daily wage rate in California was typically substantially higher than in other regions of the United States, one of the world’s highest wage countries.In an important sense the “cheap labor” in California agriculture was among the dearest wage labor on the globe.In addition, one of the remarkable features of California agriculture is that the so-called “development” or “sectoral-productivity” gap—the ratio of income per worker in agriculture to income per worker outside agriculture—has traditionally been relatively narrow.This finding in part reflects the relatively high productivity of the state’s agricultural sector. It also reflects demographic factors. Due to low rates of natural increase, California’s farm sector never generated a large home-born surplus population putting downward pressure on rural living standards. Instead, the sector attracted migrants from the surplus populations of other impoverished regions of the world. For these migrant groups, agricultural labor was an entry point into a generally robust and dynamic economy.To a significant extent, past cohorts or their descendants, through hard work and high savings rates, have managed to advance up the occupational ladder.Over the long run of California’s history, agricultural labor has not been a dead end pursuit creating a permanent class of peasant laborers. This is an important point, because the agricultural history literature laments the end of the “agricultural ladder,” whereby workers start off as laborers or sharecroppers and work their way up to cash tenants and then owners of their own farms. According to the traditional literature, ending this process represents one of the great failings of nineteenth century American society.The literature is particularly critical of California because of its large farms and high ratio of hired workers to farm owners. But a little serious thought suggests how misguided these concerns are. Engel’s Law tells us that as income per capita grows, a smaller percentage of income will be spent on food. This suggests that in a growing economy the agricultural sector would diminish in size relative to the non-agricultural sector. At the same time the closing of the frontier meant that the total supply of agricultural land could not continue to grow as it did for most of the nineteenth century. Thus, unless farms were Balkanized into smaller and smaller units there was no possible way for the nineteenth century ideal to have continued.

Under baseline conditions, agricultural land use comprised 46% of the study area. Vineyard, pasture, and row crops make up approximately a quarter each of this agricultural area, followed by grains , while alfalfa, rice, and orchards accounted for less than 4% each. Under the enhanced agriculture scenario, the agricultural footprint increased to 68% of the study area, and is reduced slightly in the restoration and urban scenarios to 44% and 43%, respectively. The developed/urban class accounted for 9% of the study area under baseline, and increased in the urban scenario to 16% of the study area by 2050 .The total amount of carbon stored on the landscape under baseline conditions was ~784,000 Mg C ha-1 , with the majority stored in row crops , riparian forests , and grassland . Carbon storage in other agricultural classes was less than 4%. Carbon storage increased by 83% from baseline in the restoration scenario to ~1.4 million Mg C ha-1, largely associated with a 4-fold increase in carbon stored in riparian forests . Areas adjacent to the Cosumnes River and its tributaries became increasingly important for this ecosystem service . In the restored landscape, the carbon stored in riparian forests accounted for 63% of the total, with proportionally less harbored in row crops and grasslands compared to baseline. In the enhanced agriculture scenario, carbon storage increased by 12% from baseline to 879,000 Mg C ha-1 ,ebb and flow bench with parcels that harbor increased carbon storage scattered throughout the study area . Compared to baseline, the proportion of carbon stored in row crops increased slightly, from 47% to 53% of all carbon stored in the study area, while the proportion of carbon stored in vegetation classes such as riparian forest and grasslands decreased by ~4% each.

In the urban scenario, carbon storage decreased from baseline by 6% to ~740,000 Mg C ha-1 . The AUC score for the BRT model performance was 0.672 . Variables with the highest relative importance for predicting Swainson’s Hawk nest sites included riparian forest, row crops, pasture, grassland, vineyards, and urban/ developed areas. We found a positive relationship between nest sites and the proportion of riparian forest, row crops, pasture, and grassland within the surrounding 25-ha landscape, and a generally negative relationship with vineyards and urban/ developed areas, matching expectations based on field surveys of habitat use. Baseline conditions showed areas adjacent to the Cosumnes River had the highest suitability for Swainson’s Hawk . The predicted landscape suitability for Swainson’s Hawk changed substantially from baseline under each of the three management scenarios. It increased the most under the enhanced agriculture scenario , followed by the restoration scenario . Parcels close to the Cosumnes River became more suitable in the restoration scenario, and parcels throughout the study area became more suitable under the enhanced agriculture scenario . As might be expected, landscape suitability declined under the urban scenario . The average suitability of each land-use scenario as calculated for each of the 15 focal bird species showed subtle changes. Average suitability across all species increased under the restoration scenario by 5% and increased slightly under the enhanced agriculture scenario , but overall suitability declined by 1% in the urban scenario . In addition, using a 5% change threshold, the restoration land-use scenario resulted in a more suitable landscape for nine out of the 15 bird species. One species, the Yellow-Breasted Chat , experienced a 5% increase in suitability under the urban scenario, and no species experienced an increase or decrease in suitability exceeding 5% in the enhanced agriculture scenario.

The total amount of nitrous oxide emission associated with baseline agriculture in the study area is approximately 50,506kg N2O. Row crops had the highest N2O emissions, accounting for 60% of the baseline emissions. The next highest emissions were associated with grain and vineyards , while pasture, orchards, and rice were less than 3%. The total amount of nitrates leached from agricultural lands is approximately 2.1 million kg N. Patterns of nitrogen leaching were similar to nitrous oxide emissions, with row crops ranking highest , followed by grain and vineyards . Again, pasture, orchard, and rice comprised less than 2% of the total. Areas of high leaching and emissions under baseline were scattered throughout the agricultural lands of the study area . In the enhanced agriculture scenario, total N2O emissions and nitrate leaching in the study area increased by about 20%, concentrated in the northwest area . Nitrous oxide emissions increased to approximately 60,000 kg N2O, and nitrate leaching to 2.6 million kg N . Similar to baseline conditions, row crops accounted for the greatest proportion of emissions and leaching. In the restoration scenario where agricultural lands were replaced by natural vegetation, total N2O emissions and nitrate leaching decreased by 3% , mostly in close proximity to the Cosumnes River . There was also an approximate 5% decrease in these figures in the urban scenario as agricultural land is developed; N2O emissions decreased to around 48,000kg N2O and nitrate leaching to 2 million kg N, respectively . Patterns of emissions and leaching among types of agriculture are similar to baseline across both the restored and urbanized landscapes. The total agricultural commodity value of the study area under baseline was ~$184 million , with a handful of high-value parcels scattered throughout the study area . Row crops accounted for almost half of this value , followed by vineyards . Agricultural types favored by the Swainson’s Hawk such as alfalfa, grains, and pasture each accounted for less than 3%.

Under the enhanced agricultural scenario, revenue increased by 48% to ~$273 million , with revenues from row crops accounting for an even higher proportion of the total revenue . The restoration scenario resulted in a 4% decrease in agricultural revenue , while the urbanization scenario resulted in a 5% decrease .Our analysis examined a highly productive agricultural landscape and quantified how different land-management scenarios compared in terms of carbon storage, biodiversity values, ecosystem disservices, and agricultural returns at the parcel scale. More specifically, we looked at the trade offs under different land-use change scenarios, and evaluated whether positive benefits in financial agricultural returns were at the expense of biodiversity and other services. Underlain by the projected changes in land-cover types in 2050, our estimates indicated that the restoration scenario had multiple positive benefits from a conservation and environmental management perspective, similar to the conservation scenario generated by Nelson et al. . Restoration yielded substantial positive outcomes for carbon storage and habitat for Swanson’s Hawk, as well as 15 other focal bird species . Concurrently, ecosystem disservices decreased , and agricultural returns also decreased . Furthermore, the amount of agricultural land in the study area only decreased slightly under the restoration scenario. At the other extreme, urbanization had consistently negative effects on the landscape, and resulted in decreased carbon storage and landscape suitability for all bird species , along with a loss in financial agricultural returns . The only positive effect from a conservation and environmental management perspective was the reduction in nitrous oxide and nitrogen leaching . From a land-use planning viewpoint, however, these relatively negative effects of expanding the urban footprint would need to be examined in the context of alternatives for meeting the housing needs of local cities . The enhanced agriculture scenario was developed based on favoring the kinds of crops commonly protected or expanded as part of Swainson’s Hawk conservation and mitigation efforts. Although managing for a single species is not ideal, in some cases it is a necessity because mitigation for habitat loss or affected protected species demands it. In other cases, a single-species approach might be pursued by management if a keystone species is identified. Either way, evaluating the effect of this strategy on ecosystem services and disservices, agricultural returns,4x8ft rolling benches and potential multi-species benefits is valuable for management. By 2050, we estimated that the enhanced agricultural landscape had a highly positive effect on Swanson’s Hawk habitat value , higher even than the restoration scenario . Landscape suitability for the 15 focal bird species also increased marginally, i.e., favorable crop types for the Swanson’ hawk were also more suitable for some of these bird species. Agricultural returns increased by almost 50%. In contrast to other studies , we found carbon storage benefitted as well , owing to a replacement of grasslands with row crops, pastures, grains, and alfalfa with higher levels of carbon storage . However, these gains came at a cost, with increases in nitrous oxide emissions and nitrogen leaching by about one fifth . The approach and scenarios used in this study provide a framework which can be adaptively modified in the future to inform land utilization. Clearly, many different or complex management scenarios could be explored. Our intent was to evaluate a range of feasible options to demonstrate the effects of major restoration on the one hand to urban growth on the other, with the enhanced agriculture scenario in the middle. One future modification, for example, would be to optimize the configuration of native and adjacent agricultural land in the restoration scenario to increase connectivity across the landscape. Alternatively, future analyses could also account for carbon storage in urban green spaces, or the value of retaining mature trees to provide nesting habitat for a listed species in the urban scenario.

In addition, other services such as groundwater could be assessed, which is particularly relevant given the recently implemented Sustainable Groundwater Management Act, or recreation, given the high visitation rates of the study area. To improve estimates of ecosystem services associated with agricultural areas, better information is needed on crop rotations over time . The study area also harbors a few registered organic farms and some contracted organic production, such as rice cultivation. Future modifications of our approach could incorporate organic land management, given the association between organic practices and decreased ecosystem disservices. Although cultivation is largely conventional, compared to many parts of California it is highly diversified, with many different types of crops across small parcels. This spatial configuration makes farm scaping practices and buffer habitats a realistic option, which, in turn, can substantially affect carbon storage and biodiversity in agricultural lands . Estimates of the focal ecosystem services could also be improved by additional data, for example, including below-ground carbon storage estimates for the forest class, estimates of soil carbon, or nitrous oxide emissions for natural habitats. Our findings using the 15 focal bird species, although subtle, indicated that management actions for the Swainson’s Hawk yielded benefits for other bird species; however, it would be useful to assess how well this was reflected in other taxonomic groups. A number of studies from central California indicate that insects might respond similarly to the restoration scenario. For example, insectary hedgerows favor beneficial insects over pests by a ratio of three to one , with the highest numbers of insects correlated with the length of flowering period. Another study found that pollination by native bees depended on the proportion of natural habitat within 1 to 2.5km from the farm site . The authors compared rates of pollination of watermelon in Yolo County, California and found that farms with ≤1% natural habitat within 1 km experienced greatly reduced diversity and abundance of native bees compared to farms with ≥30% natural habitat within 1km, meaning that pollination services by native bees had to be supplemented by imported colonies of European honey bees. This study represents one of the few ecosystem services studies conducted at a spatial scale that is relevant to the on-the-ground decision-making of land managers, county planners, and conservation practitioners. Using parcels instead of pixels is useful because changes such as cropping patterns or fertilizer application occurs by these units. The identification of parcels that exhibit consistent, beneficial changes in carbon and biodiversity from baseline conditions across all scenarios may represent focal areas for targeted protection that constitute “no regrets” opportunities for conservation investment. In contrast, conflicted parcels that harbor both beneficial services and disservices might require land-owners and municipalities to work together to develop a management strategy that optimizes the value for beneficial ecosystem services. By restoring habitat, conservation biologists and restoration ecologists seek to promote the reassembly of diverse ecological communities, while also enhancing the ecosystem services these communities provide . Restoration of pollinator communities is of particular concern because pollinators play a critical role in plant reproduction in both natural and agricultural systems .

Mannuronate and guluronate blocks of the alginate have the capability for Mn2+ binding . However, at high alginate treatment the accumulation of Mn in roots was similar to the accumulation obtained with NPs alone. More experiments are needed to explain these results. In the case of Zn, the medium alginate treatment increased its accumulation in roots by 52% compared to control. The increase of elements in roots by CeO2 NPs may be due to the enhancement of soil cation exchange capacity produced by the CeO2 NPs. A small experiment was performed to determine if CeO2 NPs increased soil CEC. Results showed that the CEC in soil spiked with 400 mg/kg CeO2 NPs was 6× compared to control. Similar to soil natural colloids, e.g. kaolin and NOM, CeO2 NPs have a large surface area, with negative surface charge , that supplies many exchange sites for cation adsorption . to CeO The concentration of Na in roots of plants exposed 2 NPs alone decreased by 10.5% compared to control. In the CeO2 NP-alginate treatments, the reduction of Na in roots was higher . This could be associated with the increase in K absorption . As a C4 plant, corn needs Na to regenerate phosphorenolpyruvate,dutch bucket hydroponic the substrate for carboxylation . Thus, reduction of Na absorption could represent a toxicity pathway of CeO2 NPs to corn plants.Concentration of macro and micro-elements in corn shoots treated with CeO2 NPs and alginate are shown in Fig. 3.

As one can see in this figure, only the concentration of K was significantly affected by the NP treatments . All the CeO2 NP-containing treatments increased the concentration of K in corn shoots. However, there were no differences between the alginate and non-alginate treatments. An outward rectifying channel mediates potassium release into the xylem, which is controlled by the stress hormone abscisic acid . Perhaps the presence of NPs up regulates the production of abscisic acid, which in turn, increases the uptake of K. The fact that higher concentrations of Al, Fe, and Mn in roots, compared to control, were not observed in shoots could indicate that these elements were bound to NPs and stuck on the surface of the roots. Divalent cations have shown to bind with alginate.Chlorophyll and other leaf pigments are related to stress response.To elucidate if the CeO2 NPs coupled to alginate impacted the photosynthesis machinery in young corn plants , chlorophyll concentration in fresh leaves of one month-old plants was determined . As seen in this figure, none of the treatments affected Chl-b fluorescence. Chl-a was not affected by CeO2NPs alone; however, the combination of CeO2 NPs with alginate, at all concentrations, significantly reduced Chl-a fluorescence, compared to control. The CeO2 NPs plus alginate at low and medium concentration reduced Chl- a fluorescence by 16.5% and 18.4%, respectively.The soil was treated with CeO2 NPs with different concentration of alginate. Error bars stand for standard deviation. an indicative of stress . There exists the possibility that the CeO2 NP treatments affected the concentration of nitrogen or silicon in the corn plants, which are related to chlorophyll production or degradation.

Heat-shock proteins are general stress related proteins involved in the protection, restoration, and degradation of damaged cell components, especially proteins, during most abiotic stresses . Western-blot analytical technique was used to determine the content of HSP 70 in fresh leaves of one month-old corn plants. As seen in Fig. 5, HSP 70 was apparently over produced in the CeO2 NP treatments including medium and high amount of alginate. Khodakovskaya et al. discovered that multi-walled carbon nanotubes induce changes in gene expression in tomato leaves and roots, up-regulating the stress-related genes, such as heat shock protein 90. The present study showed that in corn plants, the HSP 70 increased expression in response to CeO2 NPs-alginate effect. However, the specific functions or structures protected by HSPs remain unknown. Heckathorn et al. reported that the chloroplast small HSP, which function is to protect photosynthesis during heavy metal stress in corn leaves , were trigged by heavy metal. Previous studies have shown that most of the CeO2 NPs taken by plants remain in the nanopariculate form; thus, it is possible that some of the NPs present in corn leaves reached the chloroplast affecting the HSP70 expression. More studies are needed in order to decipher these uncertainties. Land-based ecosystems in the northern hemisphere appear to remove, at least temporarily, a substantial portion of anthropogenic CO# from the atmosphere . The mechanisms behind this C sink are not well understood, even though knowledge of these processes is vital to predict and interpret the responses of ecosystems to global change .

Changes in plant productivity due to CO# enrichment , nitrogen deposition , land use change , and climatic effects have been investigated as potential components . However, the response of microbial communities to these perturbations, and their potential influence on C cycling, have received scarce attention. Mycorrhizal fungi in particular might play an important role in the sequestration of C in soil under elevated CO# and N deposition. This group, which symbiotically colonizes plant roots, forms associations with 80% of plant species and is found in nearly every habitat in the world . Plants allocate an estimated 10–20% of net photosynthate to mycorrhizal fungi, although this number can range from 5 to 85% among systems . A substantial amount of C allotted to mycorrhizal tissues could be long-lived in the soil. Chitin, which is not readily decomposed , can constitute up to 60% of fungal cell walls . Arbuscular mycorrhizal fungi are also the sole producers of glomalin, a potentially recalcitrant glycoprotein . AM hyphae in the absorptive hyphal network have lifespans of only 5–7 d , and with each cycle residual hyphal C should remain in the soil. Furthermore, some micro-arthropods prefer to graze on nonmycorrhizal fungi rather than on a variety of AM fungi , and therefore might not necessarily speed up tissue turnover significantly. As a result, glomalin alone can account for 30–60% of C in undisturbed soils , assuming that the protein is 30% C by weight M. C. Rillig, pers. comm. Likewise, portions of ectomycorrhizal biomass were responsible for approx. 15% of soil organic matter in two hardwood forests . Carbon derived from mycorrhizal tissue can account for a significantly sized pool within ecosystems and globally. Because mycorrhizal fungi acquire most or all their C directly from living plants, the nutrient status of foliage strongly affects mycorrhizal growth. As elevated CO# generally increases plant growth and root-to-shoot ratio , greater allocation of C to mycorrhizal structures might follow . Effects of elevated CO# on mycorrhizal growth have been reviewed by O’Neill , Diaz , Hodge , and Staddon & Fitter , with an emphasis on changes in percentage root length colonized and total root length colonized per plant. These reviews indicate that the percentage of roots with mycorrhizal structures might not necessarily change under elevated CO# . However,dutch buckets system as root biomass tends to rise, total mycorrhizal biomass per plant might do so as well. This response varies among systems and does not necessarily occur universally. By contrast, increases in N availability through deposition or fertilization tend to reduce root colonization and fruit body production by ECM fungi . Effects of CO# and N availability on the biomass or production of extraradical hyphae have been less intensively studied or summarized. In this review, we address the current state of knowledge regarding the potential for mycorrhizal tissue to form a sink or source of C in response to elevated CO# or N deposition. First, we present an overview of processes and pools involved in the cycling of mycorrhizal C and the relevance of various measures of mycorrhizal dynamics . Interand intraspecific variations in traits that could affect C dynamics are considered. Second, we discuss known effects of CO# concentration on hyphal biomass, turnover, tissue quality and community composition. Next, we focus on the influence of N availability on these same factors, and finally we address potential interactions between elevated CO# and N availability.Processes involved in the cycling of mycorrhizal C include production, survivorship and decomposition rates of tissue. As mycorrhizal tissue grows, C is transferred from the atmosphere via plants to the pool of live hyphae. Micro-arthropods might graze a fraction of live hyphae, but grazing on AM hyphae should be low, as in feeding trials mites and collembola appear to prefer nonmycorrhizal fungi.

When grazing of AM fungal hyphae does occur, animals often only clip the hyphae, severing connections to the root but not ingesting mycelial mass . Thus changes in micro-arthropod numbers might not have a major impact on C flux from AM hyphae to soil organic matter. Instead, death rates of live hyphae determine the flflux of C from the live to the dead hyphal pool. At this point, dead tissue is distributed between active and slow soil organic matter pools as a function of tissue quality . Active soil organic matter includes sugars and other metabolites that are processed relatively quickly by decomposers; slow soil organic matter consists of recalcitrant components such as chitin and glomalin, and might last from years to decades in the soil. In plant tissues, higher N content generally speeds decomposition rates . Finally, as soil organic matter decomposes, a portion of C remains in decomposer tissues, and the rest returns to the atmosphere. Each of these fluxes and pools might be affected directly by elevated CO# and N deposition, or indirectly through changes in the composition of the mycorrhizal community.Groups of mycorrhizal fungi differ in several factors, including growth rate, that could influence C cycling. For example, isolates of ECM fungi vary markedly in productivity, both within species and among species . In AM fungi, Sanders et al. observed significant differences in hyphal biomass among three Glomus species. In addition, after 16 wk growth, total hyphal lengths of Acaulospora denticulata and Scutellospora calospora were significantly greater than those of two Glomus species in a glasshouse experiment with Artemisia tridentata . If mycorrhizal communities are altered by climate change, then variation in growth and biomass among groups could affect the amount of atmospheric C that is initially drawn into the pool of live hyphae. Mycorrhizal groups also differ in tissue qualities that might affect the rate at which this mycorrhizal C is returned to the atmosphere. Wallander et al. found that five morphotypes of ECM fungi on field-grown Pinus sylvestris varied more than twofold in chitin concentration. Likewise, glomalin content in AM hyphae differed between Gigaspora and Glomus , and significantly between Glomus caledonium and Glomus intraradices . In addition, mean N concentrations in the hyphae of four isolates of Paxillus involutusranged from 5 to 9% when grown in culture.These results suggest that the identity, as well as the amount, of mycorrhizal fungi might be important in soil C dynamics.As most mycorrhizal structures are relatively delicate and often below ground, measurements of mycorrhizal biomass, growth rate or turnover present some challenges. Most mycorrhizal studies under elevated CO# or N deposition have quantified changes in mycorrhizal colonization . This measure might be an appropriate index for nutrient transfer to the host plant . However, because extraradical hyphae account for a large portion of fungal biomass , direct measures of hyphal length are a valuable indicator of the mycorrhizal C pool . Furthermore, root colonization does not necessarily increase linearly with hyphal biomass, and environmental changes might alter relationships between the two variables. For instance, the ratio of AM hyphal length : total root length colonized by AM varied nearly twofold among CO# and N treatments in Gutierrezia sarothrae , and was nearly three times greater under ambient versus elevated CO# in a serpentine grassland . In an additional study, Staddon et al. noted a decrease in this ratio with elevated CO# in Plantago lanceolata and Trifolium repens. For this reason we focus primarily on hyphal length or biomass in this review. We emphasize that hyphal length per unit soil area is a particularly meaningful variable in field studies, and might be used eventually to scale biomass to the ecosystem or regional level. The life stage of hyphae is also an important consideration when measuring fungal productivity. Few CO# or N studies have made the distinction between live and dead hyphae when determining hyphal length.

We also demonstrate the importance of resin selection and thorough chromatography operation optimization by evaluating the cost benefit of maximizing resin binding capacity to target product. Of course, further work is needed to verify whether the use of column chromatography is needed. Transient production of thaumatin in the edible crop Spinacia oleracea was also economically competitive and captures the benefits of obviating the need for an intensive DSP. According to this analysis, the cost to produce a kg of fresh weight of spinach is $0.10, as opposed to a cheaper price for tobacco . This is attributed to the higher cost of the seeds of spinach, the longer turnaround time assumed for spinach, and the higher plant density assumed for tobacco. It is evident that field operation is very labor intensive, due to the low recipe cycle time of 2 days, which is different than the traditional time frame of growing those crops. The potential for high intra-batch variations in product yield and quality due to meteorological factors is one of the concerns of using field grown plant material for this application. These variations in turns cause inconsistency in key facility performance parameters that should be quantified using a probabilistic approach and communicated to stakeholders and will be addressed in a follow-up communication. The cost of obtaining a more controlled supply of product is reflected in the indoor upstream facilities CAPEX and COGS. This should facilitate decision making when assessing the risk and reward of each scenario.

The large-scale recombinant production of thaumatin can address the growing market need for natural,nft hydroponic safe, non-caloric sweeteners. Like stevia, the advent of thaumatin as a sugar substitute is contingent on the feasibility of its large-scale manufacturing which was addressed in this work. However, there are also social, cultural, and behavioral factors impacting sugar consumption habits that were not considered. Consumer’s preference of such products will open the door for more plant-made bio-logics for food and beverage applications, which could drive the adoption of cost-effective solutions to rising challenges through environmentally friendly and sustainable processes.While the T-DNA approach is applicable to the model plants Arabidopsis and rice, where effective transformation methods are available, it may not be feasible in many other plant species whose transformation is inefficient. Transposon can be alternatively used for insertional mutagenesis in those plants, since the generation of new insertions occurs through crossing or propagation rather than through transformation. Supported by the United States National Science Foundation-Plant Genome Program . S.Q. was supported by the Research Start-up Grants of Zhejiang Academy of Agricultural Sciences , China. P.B.F.O. was supported by EU FP5 and FP6 projects Cereal Gene Tags and CEDROME . J.-S. J. was supported by the World Class University and the Crop Functional Genomics Center projects, Korean Ministry of Education, Science and Technology, Korea.The maize Ac-Ds transposable element has been shown to be active in the plant kingdom widely .

A number of important plant genes have been cloned using the Ac-Ds element . Ds insertion libraries have been generated in Arabidopsisand rice . However, the current strategies of transposon tagging are usually slow and labor intensive and have several drawbacks. For example, in the presence of Ac transposase , transposed Ds elements may continue secondary transpositions. Unstable Ds insertions and serial transposition events may cause untagged mutations because imprecise excision or a transposition footprint can result in a mutation that is no longer associated with the transposon . Another problem is that the Ac-Ds transposable elements are highly active in rice and can transpose early in newly transformed callus cells , which results in many sibling plants carrying the same Ds insertions and consequently decreasing gene tagging efficiency. In the present study, we constructed 12 Ac-Ds transposon tagging vectors based on three approaches: AcTPase controlled by glucocorticoid binding domain/VP16 acidic activation domain/Gal4 DNA-binding domain chemical inducible expression system; deletion of AcTPase via Crelox site-specific recombination that was initially triggered by Ds excision; and suppression of early transposition events in transformed rice callus through a dual-functional hygromycin resistance gene in a novel Ds element. We have tested these vectors in transgenic rice and characterized the transposition events. Our results showed that these vectors are useful in functional genomics of rice and they will be useful for other crop plants as well.We constructed Ac-Ds transposon tagging vectors using a GVG-inducible expression system . The vectors pJJ86 and pDs-Ac-GVG carry an in cis two-element system that consists of Ds, 35S:GVG that expresses the chimeric GVG transcription activator, and AcTPase controlled by a GVG-inducible promoter.

The inducible promoter is transactivated through interaction between GVG and the 4xGAL4-upstream activating sequence . The transactivating activity of GVG is regulated by treatment with the steroid chemical dexamethasone . The Ds element in pJJ86 contains the 4x CaMV 35S enhancers for activation tagging , while the Ds in pDsAc-GVG does not. Excision of Ds from pJJ86 can be detected because in the resulting T-DNA fragment, the β-glucuronidase gene is driven by a CaMV 35S promoter. We also constructed a two-vector tagging system in which GVG-inducible AcTPase and Ds are in separate vectors . The strategy of the two-vector system is that transgenic plants carrying the GVG-inducible AcTPase and Ds are generated, respectively, and the AcTPase and Ds are combined in F1 by genetic crosses. In this case, Ds is mobilized in the presence of AcTPase in F1 plants, but stabilized after it is uncoupled from AcTPase in the subsequent generation. To test whether the inducible Ac-Ds system is functional in rice, we transformed rice cultivar Nipponbare with pJJ86. Independently transformed rice calli were cultured for 5 d on media with DEX to induce expression of AcTPase. Because Ds transposition can be detected by GUS activity, the DEX-treated calli and untreated controls were stained for GUS activity. DEX treatment of pJJ86-transformed calli exhibited stronger GUS staining than controls , indicating that the DEX inducible system in this vector is functional in rice. At the same time, there was low background of GUS activity in the untreated rice calli , suggesting that some background transposition occurred in the pJJ86 transformants.Because the Ac-Ds transposable elements are active in newly transformed callus cells and early transposition events lead to the same Ds insertions in sibling plants, we constructed a novel Ds element, designated HPT-Ds, and used the hygromycin resistance gene to suppress transposition. The pHPT-Ds1 vector carrying HPT-Ds and GVGinducible AcTPase in cis is shown in Figure 1E. The HPT gene in HPT-Ds has the same intron and triple splice acceptors as in the gene-trap Ds . Because HPT-Ds is immediately downstream of maize ubiquitin 1 promoter in T-DNA, the Ubi:HPT-Ds fusion confers hygromycin resistance, and transformed rice cells are thereby selected on hygromycin media. In case of transposition, HPT-Ds in the rice genome may not have a promoter nearby for transcription and the rice cells lose hygromycin resistance and can be counter-selected by hygromycin. To examine the efficacy of the HPT-Ds element,nft system we made a test construct containing Ubi:HPT-Ds and confirmed the function of the Ubi-driving HPT gene in a rice transformation experiment.

A total of 250 rice calli were transformed using a particle bombardment method and hygromycin-resistant cells were selected from 30 callus explants after 50 d of selection on hgromycin media. In constructing the pHPT-Ds1 vector, HPT-Ds was cloned between Ubi and GUS so that transposant cells canbe detected by GUS assay. The pHPT-Ds2 vector is similar to pHPT-Ds1 except that pHPT-Ds2 carries a Bar gene and transposition can be selected by herbicide resistance . pHPT-Ds1 was introduced into rice cultivar Nipponbare. A total of 26 stably transformed callus lines were obtained. In the condition without DEX treatment, five calli were randomly selected from each callus line and GUS-assayed for detection of transposant cells. Transposant cells were detected in 84.6% of callus lines but mosaic GUS patterns occurred at low frequency as compared with the GUS patterns of untreated pJJ86 calli . GUS assays were also carried out on 14 of pHPT-Ds1 transformed plantlets; 57.1% plantlets contained transposant cells that were rarely distributed in the tissue . The results of pJJ86 transformants and pHPT-Ds1 transformants indicated that there was background transposition activity in the rice calli and plantlets selected from hygromycinmedia, and that the growth of rice cells containing HPT-Ds transposition events were partially suppressed by hygromycin counter selection. To characterize the HPT-Ds excision events, rice genomic DNA of eight GUS-positive pHPT-Ds1 transformants was extracted and examined in nested polymerase chain reaction reactions using Ubi- and GUS-specific primers . Reconstructed Ubi:GUS sequence containing the HPT-Ds empty donor site was confirmed by sequencing the 657-bp PCR product . These results suggested that HPT-Ds elements in the pHPT-Ds1 transformants excised from the T-DNA. To get more information about the background transposition in the GVG-inducible AcPTase system, we constructed pHPT-Ds3 and pHPT-Ds4 by removing the 35S:GVG from pHPT-Ds1 and pHPT-Ds2, respectively. According to the GUS assay results of pHPT-Ds3 transformed callus lines, 57.1% of the callus lines showed somatic transposition. The mosaic GUS patterns of pHPT-Ds3 transformants were similar to those of pHPT-Ds1 transformants and the transposition frequency was a little lower than 84.6% of the pHPT-Ds1 calli. Our explanation for the results of pHPT-Ds1 and pHPT-Ds3 is that the background transposition in the GVG-inducible Ac-Ds system was primarily due to a low-level leaky expression of 4xUAS:AcTPase .The HPT-Ds element described in the present study is a novel Ds whose HPT gene has a dual function. During plant transformation and selection, HPT expression relies on the upstream Ubi promoter to confer resistance to hygromycin in selection media. In case of transposition, the HPT gene may be inactive because the 5 flanking sequence of HPT-Ds at a new genomic site may not be able to provide promoter activity. It is conceivable that most of the transposant cells become sensitive to hygromycin. Therefore, the counter-selection nature of the HPT gene in HPT-Ds can be used to diminish transposant cells in newly transformed rice calli on hygromycin media. In testing pHPT-Ds1 and pHPT-Ds3, it was observed that early transposition events in transformed calli and plantlets were suppressed by hygromycin. Few transposant cells in the calli and plantlets were able to grow under the hygromycin selection pressure, which might be due to escaping transposant cells or because of promoter activity of the 5 transposon flanking sequence. Because transposition requires transposase, an important theme in transposon tagging research is how to efficiently control transposase activity.

It was reported that AcTPase driven by strong promoters mediated high-frequency Ds excision in several dicot plants . Strong double enhancers of CaMV 35S promoter adjacent to wild type Ac element induced high-frequency Ac excision in rice transformation . In the present study, we have used the GVG-inducible promoter to control AcTPase expression and transposition was induced to high levels by DEX treatment of pJJ86 transformed callus. However, we also observed a leaky expression of AcTPase in the GVG-inducible Ac system in the transformants of pJJ86, pHPT-Ds1 and pHPT-Ds7 based on GUS assay results. Our explanation is that the transposition background was primarily from a low level of leaky expression of 4xUAS:AcTPase. Consistently, in the pHPT-Ds3 and pHPT-Ds5 vectors that do not have 35S:GVG, 57.1% of the pHPT-Ds3 transformants and 76.6% of the pHPT-Ds5 transformants still showed transposition in somatic cells. In spite of the wild type Ac element having a weak promoter that supports only 0.2% expression of the CaMV 35S promoter , the wild type Acitself can transpose in rice with a relatively low activity for three successive generations . This indicates that a weak expression of AcTPase can cause transposition events. In Southern blot analysis of genomic DNA of pHPT-Ds7 and pHPT-Ds8 transformants, the 5.4 kb hybridizing band represented the HPT-Ds at FDS in T-DNA. For the hybridizing bands larger or smaller than 5.4 kb, we explain that some of the bands might be from transposed HPT-Ds. The pHPTDs7 transformants showed transposition in somatic cells as suggested by GUS assay results. Because the rice genomic DNA for Southern hybridization was extracted from few leaves of a transformant, transposition in other leaves might not have been detected in the results. Also, since a rice transformant may have more than one T-DNA copy and may contain rearranged T-DNA, the hybridizing bands larger or smaller than 5.4 kb might possibly be from transgene rearrangement. Nevertheless, the efficacy of the HPT-Ds element when it was brought together with the GVG-inducible-AcTPase and the Cre-lox recombination system in pHPT-Ds7 and pHPT-Ds8 was confirmed by GUS assay and Southern blot analysis.

Since these technologies are unlikely to be mission critical during Artemis, their TRL can be increased and their risk factors studied through in-space evaluation. The Artemis missions also provide a test bed to evaluate the space-based evolution of microbes and alterations of seed stocks as a risk inherent to the biological component of the biomanufactory. This risk can be mitigated by incorporating backup seed and microbial freezer stocks to reset the system. However, ensuring that native and/or engineered traits remain robust over time is critical to avoid the resource penalties that are inherent to such a reset. Consequently, while optimal organisms and traits can be identified and engineered prior to a mission, testing their long-term performance on future NASA missions prior to inclusion in life support systems will help to assess whether engineered traits are robust to off-planet growth, whether microbial communities are stable across crop generations, and whether the in situ challenges that astronauts will face when attempting to reset the biomanufacturing system are surmountable. Quantifying these uncertainties during autonomous and crewed Artemis missions will inform trade off and optimization studies during the design of an enhanced life support system for Martian surface bio-operations.Crewed surface operations of ∼ 30 sols by four to six astronauts are projected to begin in 2031 ,growing tomatoes hydroponically with an additional mission similar in profile in 2033 . Given the short duration, a mission-critical biomanufactory as described herein is unlikely to be deployed.

However, these short-term, crewed missions RMA-S1, S2 provide opportunities to increase the TRL of biomanufactory elements for ∼ 500 sol surface missions RMA-L1 in ∼ 2040 and RMA-L2 in ∼ 2044. Building on the abiotic ISRU from early Artemis missions, we propose that RMA-S1 carry experimental systems for C-and-N-fixation processes such that a realized biomanufactory element can be properly scaled . Since RMA-S1, S2 will be crewed, regolith process testing becomes more feasible to be tested onsite on the surface of Mars, than during a complex sample return mission. Additionally, while relying on prepacked food for consumption, astronauts in RMA-S1 will be able to advance the TRL of platform combinations of agriculture hardware, crop cultivars, and operational procedures. An example is growing crops under various conditions to validate that a plant microbiome can provide a prolonged benefit in enclosed systems, and to determine resiliency in the event of pathogen invasion or a loss of microbiome function due to evolution. Additionally, the TRL for crop systems can be re-evaluated on account of partial gravity and/or microgravity. The RMA-S1 and RMA-S2 crews will be exposed for the first time to surface conditions after interplanetary travel, allowing for an initial assessment of health effects that can be contrasted to operations on the lunar surface , and that may be alleviated by potential biomanufactory pharmaceutical and functional food outputs . The RMA-S1 and RMA-S2 mission ISRU and FPS experiments will also provide insight into the input requirements for downstream biomanufactory processes. ISM technologies such as bioplastic synthesis and additive manufacture can be evaluated for sufficient TRL. Further, loop closure performance for several desired products can also be tested. This will help estimate the impact of waste stream characteristics changes on recycling .We have outlined the design and future deployment of a biomanufactory to support human surface operations during a 500 days manned Mars mission.

We extended previous stand-alone biological elements with space use potential into an integrated biomanufacturing system by bringing together the important systems of ISRU, synthesis, and recycling, to yield food, pharmaceuticals, and bio-materials. We also provided an envelope of future design, testing, and biomanufactory element deployment in a roadmap that spans Earth-based system development, testing on the ISS, integration with lunar missions, and initial construction during shorter-term initial human forays on Mars. The innovations necessary to meet the challenges of low-cost, energy and mass efficient, closed-loop, and regenerable biomanufacturing for space will undoubtedly yield important contributions to forwarding sustainable biomanufacturing on Earth. We anticipate that the path towards instantiating a biomanufactory will be replete with science, engineering, and ethical challenges. But that is the excitement—part-and-parcel—of the journey to Mars.Doubled haploid techniques have established themselves as useful tools in plant breeding and genetic research. As of 2005 doubled haploids had been produced in over 230 different crops . DH lines can be produced in several ways, by distant hybridization , by androgenesis or by gynogenesis . Each method has some advantages and disadvantages and not all are applicable or efficient in all crops. As discussed by Forster and Thomas 2005 the advantage of DH in breeding is in time savings between the initial cross and large-scale testing of developed lines.The advantage of DHs in genetic research is that perfectly homozygous lines can be produced relatively quickly and permit large scale replicated trials for detection of quantitative trait loci and their allocation to specific, sometimes very small, chromosome regions. In all cases, the critical issue in the use of double haploids is the efficiency of their production. This efficiency can be measured in several ways but it can always be brought down to the ultimate factor: how many useful lines can be produced in a given time with available labor and resources. For those involved in the DH development, the critical measure of efficiency is the number of green plants produced.

However, not all green plants need to be useful in breeding or research. Given that stability/uniformity is the main advantage of the DH lines, any deviation from it, including that caused by aneuploidy, is detrimental and in most cases will disqualify a line from any research or breeding. Triticale is a new cereal that in ca. 135 years since the first man-made wheat-rye hybrids were created has established itself as a competitive crop in certain environments. Unlike its progenitors, wheat and rye, triticale is generally amenable to anther culture and in most instances produces reasonable yields of haploids. First commercial cultivars of triticale developed with the aid of androgenesis have been released and the method is routinely used in breeding with thousands of DHs produced every year . The androgenic response in triticale appears to be under genetic control but in most cases, sufficiently large populations can be generated. However, despite a considerable progress in breeding for meiotic stability, triticale still has chromosome pairing issues and tends to show a fair proportion of aneuploids among sexually derived progenies, more so in hybrids than established lines . Perhaps for this reason,hydroponic growing supplies the issue of efficiency of the DH production and the quality of the recovered DH lines requires more attention in triticale than in most better established and more meiotically stable crops, such as wheat or barley. The wider context of this study was to generate sufficiently sized mapping populations of the DH triticale lines. Aneuploidy severely complicated this effort and appeared as an issue deserving to be analyzed with an additional effort. However, since from the start the emphasis was on the mapping populations and not the process of androgenesis itself, some data on population sizes and frequencies of specific events were never collected. Still, it appears that the issue of aneuploidy in triticale DH lines is important enough to be addressed.The measurements of the DNA contents were done on a population of spontaneously DHs of the Presto 9 Mungis combination. Ploidy levels of the regenerated plants were evaluated by fluorescence using a Partec II flflow cytometer . Samples were prepared according to Galbraith et al. with some modifications. Leaf fragments were chopped with a sharp razor blade in a Petri dish with 2 ml of the nuclei-isolation buffer Triton X-100 containing DAPI and the cell suspension was filtered through a 30-lm filter. The ploidy levels of regenerants were determined by comparing the G1 peaks of the analyzed samples to internal controls, here both parents, cv. Presto and Mungis. Plants with the peaks of the DNA contents distribution clearly separated from the controls were considered aneuploid.Root tips for karyotyping were collected either from seed germinated on wet filter paper in Petri dishes, or from plants grown in a hydroponic culture in an aerated full strength GroResearch Gromagnon 9-5-18 All-Purpose-Nutrient solution from American Hydroponics, Arcata, CA USA. For collections from germinating seedlings, seed were placed on wet filter paper in Petri dishes for 2–3 days at room temperature, refrigerated at ca.2℃ for 2–3 days, transferred to room temperature for 24 h and collected to ice water for ca. 27 h. Depending on the intended cytological protocol, roots were either fixed in 45% acetic acid overnight and squashed, or fixed in a Carnoy solution .

Roots from the hydroponic-grown plants were collected to ice water for ca. 27 h and fixed in the Carnoy solution. For the analyses of meiotic metaphase I chromosome pairing one anther from a spikelet of an ear was excised and live-squashed in a drop of 1% acetocarmine. If MI was present, the remaining two anthers were fixed in the Carnoy solution. All material in the Carnoy solution was fixed for 7 days at 37℃, stained in 1% acetocarmine for 2 h, re-fifixed and stored at -20℃ until used. All preparations of this type of material were made by squashing in a drop of 45% acetic acid using the two-coverslip technique. All C-banding on the 45% acetic acid- fixed root tips was according to Lukaszewski and Xu ; all C-bandning on the Carnoy-fixed material, whether root tips or anthers, was according to Giraldez et al. . In situ probing with labeled DNA was done according to the protocol of Dr. T. Endo, Kyoto University, Japan . Total genomic DNA of rye was labeled with digoxigenin and detected by the antidigoxigenin-fluorescein using standard kits and protocols from Roche Applied Science . The probe was mixed with blocking wheat DNA prepared according to MasoudiNejad et al. , usually in the probe to block ratio of ca. 1:100. Counter staining was with 1% propidium iodide. Sequential C-banding- in situ probing were done using the protocol provided by Dr. T. Endo, Kyoto University, Japan. For sequential C-banding- in situ probing, preparations were made in the same fashion as for standard in situ probing, they were C-banded, analyzed and photographed. The slides were then de-stained air dried, and probed using the Masoudi-Nejad et al. protocol. The cells photographed after C-banding were re-photographed after the in situ probing. All observations were made under a Zeiss Axioscope 20 equipped with epi-fluorescence, recorded with a SPOT RT Color digital camera , and processed using the SPOT Advanced and Adobe Photoshop CS software to improve contrast and resolution.The larger purpose of this study was to generate useful DH lines and no detailed records of the regeneration rates/ success were collected for every attempt or in every season. The total number of green androgenic plants transplanted to soil exceeded 3,500. Weak green plants that did not grow well in test tubes were not transplanted and no record exists of their numbers/proportions. Of the transplants, a certain proportion died before the colchicine treatment and the weakest of the survivors were not colchicine-treated. The estimated overall proportion of weak green plants rejected before colchicine treatment was about 8%, but in different cross combinations it ranged from ca. 2–3% toca. 70% in the group of late regenerants in Presto 9 NE422T. Mortality due to colchicine was low . Seed set per colchicine-treated plant ranged from a single seed to complete fertility. Complete fertility is probably indicative of spontaneous chromosome doubling in early microspore divisions rather than an effect of colchicine. In three cycles of androgenesis that included 644 colchicine-treated plants for which fairly detailed counts were made, 157 green plants were deemed to be aneuploid, based on their morphology at flowering. Most of these presumed aneuploids did not set seed. Those that did set seed and had their progeny karyotyped, all were aneuploid. Among plants that appeared normal in C0 and set seed, additional 16 were deemed aneuploid based on their morphology and seed set in C1, and all were found to be aneuploid upon karyotyping. Therefore, the average frequency of aneuploids among all regenerated green plants from all cross combinations must have exceeded 35%. In one of the most recalcitrant combinations, NE422T 9 Stan 1, among 72 plants that survived colchicine treatment, 50 were morphologically abnormal and were considered aneuploids.

The concentration of toluene in the building exhaust was 120 µg m-3, more than double the highest level measured indoors, suggesting a possible toluene source in the restrooms. The cleaning compound 2-butoxyethanol was slightly higher indoors, but at very low concentrations.The compounds listed in this category have many sources, including outdoor air. For the most part there was little difference across the building spaces for these compounds, and little difference from the ambient air measurement. The single exception to this observation is methylene chloride that appears to increase by about a factor of ten indoors. It is possible that this compound is in use as a cleaning solvent, or it may be present in computer equipment or other supplies. Methylene chloride is also used as a spot remover in dry cleaning processes and may be carried into the building on occupant clothing. The levels of this compound were low relative to health standards . Note that for compounds where measurements were below the LOQ the relative difference may be an artifact of imprecision of measurement rather than a reflection of real differences. These values should be interpreted carefully. 

In Table 4 the compounds which display relative reductions between two zones are shaded a tan color,growing tomatoes hydroponically while those with relative increase of factors of tens are shaded light green, and those with relative increases by factors of 100 are shaded red.  The HVAC inlet to the building which includes an air washer and filtration showed a reduction of all measured VOCs and aldehydes with the exception of octanal, 1,4‐ dichlorobenze, decamethylpentasiloxane, phenol, TXIB and diethylpthalate. The reductions were ranged from 4% to 100% for 2‐butoxyethanol, d‐ limonene, trichloroethylene, and a‐pinene. The plasticizer concentrations increased140% and 320% as the air moved from outside into the greenhouse. VOC concentrations all increased as the air was transmitted through the greenhouse. The concentration of the odorous compounds hexanal and nonanal increased by 68% and 110%, respectively in the greenhouse. Most other compounds showed modest increases on the order of 10s of percentage points, although styrene concentrations increased by almost a factor of 7 in the greenhouse.  With only a few exceptions , VOC and aldehyde concentrations increased as the ventilation air moved from the greenhouse into the occupied building spaces. Increases between the average indoor concentrations and the greenhouse air exit ranged from 6% for toluene to a factor of 120 for the cleaning solvent 2‐butoxyethanol. The cleaning solvent d‐limonene increased by a factor of 56, methylene chloride increased by a factor of 11, and a‐pinene by a factor of 64.Diethylpthalate increased by a factor of 21. 

Odorous compounds hexanal, nonanal, and octanal all increased by factors of two to four, as did the irritating and carcinogenic compound formaldehyde. The deodorant 1,4‐dichlorobenzene concentration increased by over a factor of six. The concentration of the VOCs and aldehydes in the HVAC exhaust stream was in only a single case lower than the incoming air , where it was zero in the exhaust. D‐limonene was 19 fold higher in the exhaust than the intake, 1,4‐ dichlorobenzen was 76 fold higher, and diethylpthalate increased 17 fold. Concentrations in the exhaust vs. greenhouse tended to be higher than the comparison to the ambient air – this is due the observed decrease at the intake relative to the greenhouse – possibly the benefit of the air washer. Overall, exhaust concentrations exceeded that supplied to the zones containing plants by small to large multiples. The concept that the building air is scrubbed clean of gaseous air contaminants by the plants is not supported by the data. This being said, it is not known what the building IAQ would be without the plants. Table 5 provides a comparison between the measured indoor VOC and aldehyde concentrations in the PBC and those measured in a survey of office buildings in the United States . From 1994 to 1998 the U.S. Environmental Protection Agency  conducted the Building Assessment and Survey Evaluation Study of 100 randomly selected office buildings in the continental U.S. . The data in Table 5 are summary statistics of measurements taken from the BASE study . Note that not all of the VOCs measured in the PBC were studied in the BASE study, and vise‐versa. The BASE study did not measure all of the listed compounds in all 100 buildings as can be seen from the Table. Compounds for which the PBC had more that a factor of two greater indoor concentrations than the BASE Study mean are 1,4‐dichlorobenzene, methylene chloride , and TXIB. 

The measured PBC formaldehyde and acetaldehyde levels were both above the mean BASE Study levels by more than one standard deviation. Compounds for which the PBC had one half or less of the concentration of the BASE Study indoor concentrations included 2‐butoxyethanol, acetone, d‐limonene, phenol, and styrene. Both 2‐butoxyethanol and d‐limonene are cleaning agents that may be used less frequently in the PBC than in the U.S. office buildings. The compound measured that is of greatest concern is formaldehyde, as discussed above, which has an 8‐hr average REL of 9 µg m‐3. The average across the measured spaces in Floors 5 and 3 was 28±1.4 µg m‐3. However, the observed formaldehyde concentrations fall within levels that have been recorded in U.S. office buildings . The observed levels of odorous compounds hexanal, nonanal, and octanal may detract from perceived air quality in the PBC, as the observed concentrations exceed document odor thresholds. However the levels may not be high enough to be irritating to occupants. The presence of 1,4‐dichlorobenzene in the ambient and greenhouse air suggests that some short circuiting of ventilation exhaust back into the building. It may also be possible that some leakage across the heat recovery wheel is slightly contaminating the fresh intake air. The removal of ambient particulate matter by the PBC rooftop air handler, the particle loss mechanisms in the air transit through greenhouse and ducting into the building, and the re‐circulating filtration of air by the floor level AHUs appears to be rather successful. Indoor PM2.5 was reduced to 26±8 µg m-3 7% of outdoor levels.  There are no indoor standards for PM2.5, but the World Health Organization has set the outdoor 24 hour standards at 25 µg/m3, and the annual PM2.5 standard at 10 µg/m3 . Considering the extremely high outdoor PM2.5 levels in New Delhi, the protective environment provided by the PBC is phenomenal. This one‐day study did not measure all possible air contaminants in the PBC or surrounding outdoor air. Ozone is an important air contaminant that was not measured, that may have a bearing on IAQ in the building. On January 1 the ozone level in the ambient air was likely around it’s lowest for the year as its formation is dependent on radiation from the sun, and it varies with the seasons. However, during other times of the year, ozone entrained into the building could have a significant impact on IAQ as it reacts with d‐limonene, a‐pinene, and other alkene compounds. Future work should include a study of ozone entry into the building. Rose production is currently the largest component of California’s $300 million cut-flower industry. In 2001, California growers produced 66% of the U.S. rose crop, with a wholesale value of $45 million . The key pests of cut roses are two spotted spider mites , western flower thrips and rose powdery mildew . The two spotted spider mite is a foliage feeder that extracts the cell contents from leaves. This feeding causes foliar stippling and can disrupt the plant’s photosynthetic and water balance mechanisms . The western flower thrips is both a foliage and flower feeder, although it feeds primarily on flowers in the cut-rose system . Powdery mildew is probably the most widespread and best-known disease of roses. The fungus produces a white, powdery-appearing growth of mycelium and conidia on leaves,hydroponic growing supplies which can cause distortion, discoloration and premature senescence. Although it causes some disruption of photosynthesis and transpiration control, the key impact of powdery mildew is reduced aesthetic value caused by the white, powdery spots and leaf distortion. Fresh cut roses are often harvested twice daily, so revised reentry intervals imposed by the U.S. Environmental Protection Agency after pesticide application limit the number of pesticides that are useful in this production system .

In addition, the typical number of pesticide sprays applied to roses grown for cut flowers has impeded the implementation of integrated pest management procedures, particularly the use of biological controls. The IPM approach to pest management incorporates all cost-effective control tactics appropriate for the crop, including biological, cultural and chemical controls. Pesticides that target hard-to-kill floriculture pests frequently kill natural enemies as well, which favors continued reliance on conventional pesticides while discouraging the adoption of biological control. Heavy pesticide use against key pests in the greenhouse has resulted in the widespread development of pesticide resistance in western flower thrips , mites , white flies , aphids and leaf miners . The heavy use of pesticides in cut roses is also a worker safety concern in global and local production. California rose growers reached a crisis point about 8 years ago, when pesticide resistance, costs and limited pesticide availability threatened the growers’ ability to effectively manage two spotted spider mites. At the same time, a new cut-rose production system that favors the success of IPM was gaining widespread acceptance. Roses were traditionally grown in soil with a hedgerow training system, where flowers are cut in a manner that gradually creates a 7-foot or taller hedge. The hedges are pruned back annually to about a 3-foot height and the process is begun again. With the new bent-shoot method, plants are grown in raised containers in a modified hydroponics system. Most of the shoots are bent downward at the crown to intercept more light, creating a perennial lower canopy that exists for the 5 to 8 years of crop production. The upper canopy contains only stems that produce flowers, which take 45 to 52 days to develop. The bent-shoot method creates a spatial separation between the harvested flowers and perennial foliage that does not exist in standard roses. Pesticides to control western flower thrips and powdery mildew that are more compatible with mite predators have also recently become available. These developments, coupled with the difficulty that rose growers were facing in controlling spider mites, made us confident that we could develop a successful IPM program that rose growers would adopt. This project was initiated in 2000 with major funding from the Pest Management Alliance Program of the California Department of Pesticide Regulation and was later supplemented with additional funding. The goal of the Alliance project was to foster a team approach to the development and implementation of IPM programs in a given commodity and to document a reduction in traditional pesticide use. Our Alliance team included researchers, county-based advisors, growers, chemical and biological-control industry representatives, commodity associations and government officials. Our objective was to develop a cost-effective IPM program for the key pests of cut roses that included sampling, thresholds, biological control and directed sprays of reduced-risk pesticides.Eight growers spanning the major rose-producing areas of California participated in the program. Each grower contributed an IPM and a conventional-practice greenhouse; all greenhouses were between 5,000 and 10,000 square feet in size. All pest management decisions in the IPM greenhouses were based on the IPM program that we developed, while the grower made all pest management decisions in the conventional greenhouses. Data was collected and compared on a weekly basis by trained scouts using a comprehensive sampling plan that provided information about the density of insects, mites and diseases. The project included growers with several different rose varieties and both the bent-cane and hedgerow training techniques, but we kept these two variables standardized within a location. Implementation began in March 2000 and continued until January 2001. Fixed precision sampling plans that had been previously developed for two spotted spider mites and western flower thrips were used in our scouting program. This type of sampling plan was developed through intensive surveys of a crop to determine a pest’s spatial distribution. The degree of acceptable error was decided upon in advance, and the number of samples needed to obtain that precision was calculated using knowledge of the pest’s spatial distribution in the crop.

Direct investigation of N2O production and fate in the soil profile has not advanced far, and is only beginning in the fertigation context. It is increasingly clear that much, if not most, soil N2O might be reduced before emission from surface. It is commonly assumed that the upper 20 cm play the central role in surface emissions ; in this study, production of emitted N2O was centered at the 10–15 cm depth. Calculations of net N2O production at different depths in the soil showed more overall N2O consumption than production at 20 cm and below, helping to explain lower emissions under NO3 treatments, where points of production were deeper. N2O production near surface has been difficult to measure, but is a missing link of great importance. The measurement and simulation of soil O2 availability, varying as it does at different points in soil aggregates, remains an obstacle that impedes comparison of field and laboratory soils. Basic questions also persist over fertilizer N availability in its different stages of transformation. And field trials have not verified whether fertilizer management can affect the completeness of N reduction in classical or nitrifier denitrification.In the past decade, nanoscale fertilizers and pesticides have been increasingly proposed and used in agriculture.In particular copper-containing nanopesticides are being introduced to the market due to their excellent antimicrobial and anti-fungal properties.The increasing use of nanopesticides in agriculture has motivated researchers to consider their environmental fate, bio-availability, and toxicity to edible plants.

Extensive investigations of bio-accumulation and phytotoxicity of copper-based nano pesticides 2) on a variety of crop plants, for example, radish , ryegrass , cilantro , zucchini , bean , wheat , duck weeds , lettuce , alfalfa , have been conducted.However, most studies spiked NPs in soil or via water in hydroponic systems,hydroponic growing system whereas in commercial agriculture most copper related pesticides are applied through foliar spray.Compared with the soil-root transfer, the leaf-root transfer pathway and toxicity mechanism have rarely been investigated and are poorly understood.Terrestrial vascular plants have the ability to uptake metals, organic contaminants, even nanoparticles through the leaves employing different pathways.Ions are able to penetrate the leaf cuticle and enter the cytosol of epidermal cells or mesophyll cells.For fine particles , stomatal uptake is an important pathway.For example, Uzu et al. reported that lettuce leaves contained 335 ± 50 mg Pb kg−1 after exposure to Pb-enriched fine particles for 43 days.Hong et al. showed that CeO2 NPs were taken up through cucumber leaves and translocated to root tissues.Lettuce is a widely cultivated vegetable and usually used as a model plant in contaminant transfer studies.Furthermore, since the leaves are the edible part of lettuces, investigating their foliar uptake of copper based nanopesticides is of high interest for risk assessment of human and ecological health. Copper is a redox active transition metal and is involved in redox reaction in cells, generating O2 •− and ·OH via the Haber Weiss and Fenton reactions.Once copper particles/ions enter into plant tissues, no matter where they are localized, they may induce oxidative stress and affect several metabolic processes.Metabolomics is a powerful approach for gaining a comprehensive understanding of biological mechanisms, including toxicity, generally by monitoring low molecular weight metabolites.In recent years, various technologies have been employed for metabolic investigations of organism responses to environmental stressors.

Rather than target a limited number of metabolites or physiological parameters, nontargeted metabolomics can provide information on a large number of metabolites, which results in a deeper insight into the molecular mechanisms underlying the physiological and biochemical changes. In addition, metabolomics can be used to reveal the mechanism of plant defense and detoxification of contaminants.Pidatala et al.performed metabolomics studies and revealed detoxification and tolerance mechanism of Vetiver to Pb. Our recent study on cucumber plant root exudate metabolomics revealed that exposure to nano-Cu up-regulated a number of amino acids that bind with copper NPs and ions, likely to detoxify Cu from its nearby environment.The primary aim of this work was to determine the metabolic profile changes in plants exposed to Cu2 nanopesticides using GC-TOF-MS. The objective is to elucidate the toxicity and detoxification mechanisms underlying up- or down regulated metabolites. In addition, knowledge on the uptake and translocation of Cu2 nanopesticides and released Cu ions in lettuce leaves, through foliar application, is of high interest for risk assessment.The Cu2 nanopesticide used in this study were in the form of a commercial biocide . Detailed physicochemical properties of Kocide 3000 have been reported before.Specifically, the primary particle size is ∼50 to >1000 nm. The hydrodynamic diameter is 1532 ± 580 nm and the zeta potential is −47.6 ± 43 mV, measured via Dynamic Light Scattering , in NanoPure water at pH 7. Although Kocide 3000 particles are mainly micron-sized, these micronized particles are made up of nanosheets of Cu2 that are bound together by an organic composite and can potentially redissociate in water.For this reason the pesticide is considered “nano”. Copper content in Kocide 3000 is 26.5 ± 0.9%, while other elements including C, O, Na, Al, Si, S, Zn compose 73.5% of mass.Lettuce seeds were purchased from Seed Savers Exchange . The soil was collected from the Natural Reserve System of UC Santa Barbara , from the top 20 cm. The soil texture is sandy loamy grassland with sand/silt/clay percentage of 54.0%, 29.0% and 17.0%. Soil pH is 5.90 ± 0.04. Loss-onignition organic matter is 3.11 ± 0.07%. Cation exchange capacity is 25.8 ± 0.1 mequiv 100 g−1 .

More information regarding the soil composition was reported in a previous study.Lettuce seeds were planted in pots containing 250 g of soil. Each pot contained one seed. Plants were grown in a greenhouse, which was maintained at 28 °C by day and 20 °C by night. The daily light integral was 17.3 ± 3.6 mol m−2 d−1 . When plants were 24 days old, we began to spray them with Kocide 3000 suspended in NanoPure water at 105, 155, and 210 mg Kocide/100 mL. The doses were selected generally following the manufacturer’s recommendation . Before spraying, the suspension was sonicated for 30 min in cooled water. A hand-held spray bottle was used for spraying. The lettuces were sprayed a total of 8 times during 4 weeks; the amount sprayed each time was 8.75 , 12.9 and 17.5 mg/pot. Each spray was ∼1 mL. The seven treatments were: control; low, medium, and high NPs in uncovered soil; low, medium and high NPs in covered soil. Each treatment was replicated five times. In covered samples, the soil was covered with filter paper. In covered soil, Cu detected in root should be only from leaf translocation. In uncovered soil, Cu in root not only comes from translocation, but also from soil, because the soil was also exposed to some Cu2 nanopesticide during spraying. This allows us to determine whether the Cu NPs were translocated from leaf to root. At 52 days after planting, all plants were harvested.At harvest, the lettuce plants were gently removed from the soil, thoroughly rinsed with tap water for 5 min and then rinsed with NanoPure water three times. Leaf tissue was carefully separated from vascular and mesophyll tissues Figure S1. Mesophyll and root tissues were ground in liquid nitrogen and lyophilized for 5 days. Part of the freeze-dried mesophyll tissues were sent to UC Davis for metabolomics analysis, and another portion was ovendried at 70 °C for ICP-MS analysis. Since only a small amount of vascular tissue was available,vertical grow table it was only oven-dried for metal analysis.Dried plant tissues were digested with a mixture of 4 mL of H2O2 and 1 mL of plasma pure HNO3 using a microwave oven system at 165 °C for 1 h. The standard reference materials NIST 1547 and 1570a were also digested and analyzed as samples. The recoveries for all elements were between 90 and 99%. Cu and other six important mineral elements were analyzed using inductively coupled plasma mass spectrometry .The freeze-dried lettuce tissues samples were subjected to GC-TOF-MS analysis at the Genome Center Core Services, University of California Davis to identify the metabolites present in lettuce tissues. A description of sample pretreatment, analytical method and instrument has been described by Fiehn et al.Briefly, an Agilent 6890 gas chromatograph containing a Rtx-5Sil MS column with an additional 10 mm integrated guard column was used to run the samples, controlled using Leco ChromaTOF software version 2.32 . quantification was reported as peak height using the unique ion as default. Metabolites were unambiguously assigned by the BinBase identifier numbers using retention index and mass spectrum as the two most important identification criteria. More details regarding data acquisition, data processing and data reporting are provided in the SI.Partial least-squares discriminant analysis is a supervised clustering method, which uses a multiple linear regression technique to maximize the separation between groups and helps to understand which variables carry the class separating information.PLS-DA was run based on GC-TOFMS data using online resources.

Variable Importance in Projection is the weighted sum of the squares of the PLS-DA analysis, which indicates the importance of a variable to the entire model.A variable with a VIP above 1 is regarded as significant.Biological pathway analysis was performed based on all detected metabolites data using MetaboAnalyst 2.0.The impact value threshold calculated for pathway identification was set at 0.1.Cu in leaves increased in a dose-dependent manner in both covered and uncovered soil . Cu increased 82−140 times in vascular and 115−184 times in mesophyll tissues relative to the control, which indicates a high bio-accumulation of copper/nanoparticles in leaf tissues. Even though the leaves were thoroughly washed, copper ions and NPs remained on the surface or were incorporated into leaf tissues; it is likely that washing was not 100% efficient in removing them. Leaf exudates can form weak acids in the presence of water,which can accelerate dissolution of Cu2 nanopesticide, releasing cupric ions as long as the water remains on the leaf. This may result in a pathway for cupric ions to penetrate the epidermis cells and translocate to other tissues. In addition to ionized Cu, nanoparticles smaller than the stomatal diameter may enter past the guard cells. Stomatal diameters range from 8 to 12 μm for several species.Even though trichomes are not abundant on lettuce leaf surfaces, ESEM images taken after 24 h exposure to Cu2 nanopesticides show that many small particles were deposited on the lettuce leaf surface and stomatal cavities. The typical diameter observed for lettuce stomata is 13.1 μm , which is large enough to permit entry to Cu2 nanopesticides aggregates with an observed hydrodynamic diameter of 1530 ± 580 nm. Eichert demonstrated that 43 nm NPs entered stomata and migrated along the surface of stomatal pores.After passing the stomatal guard cells, the NPs may either attach to cell walls or move between cell walls. For example, Stamenkovic and Gustin showed the majority of foliar Hg was located in epidermal and stomatal cell walls and was rarely found in mesophyll or vascular tissue.However, Hong showed that Ce was present in cucumber root phloem after foliar application of CeO2 NPs.As seen in Table 1, the average [Cu] in control roots is 6.0 mg/kg, while in treated plants, [Cu] in root is 17.5−26.1 mg/kg in covered soil and 34.2−56.9 mg/kg in uncovered soil. Statistical analysis showed all the NP treated plants have significantly higher [Cu] in roots compared to controls, even though application was only foliar. In covered soil, where no direct root uptake could occur, Cu in the roots was translocated from the leaves via phloem loading. Liao et al. showed that some xylem-transported Cu was recirculated to roots via the phloem in chicory and tomato plants.Even though we observed evidence of Cu translocation to the roots, 97−99% of Cu mass was retained in the leaves. In addition, the translocation rate in NP-treated plants was 0.009 to 0.014, which is far lower than that in the control . This indicates plants sequestered most of the Cu in leaves.The threshold level for Cu to induce toxicity in plants is 20−30 mg/kg.However, high concentrations of Cu in lettuce leaves did not cause any visible toxic symptoms throughout the entire exposure period . On the contrary, the leaf biomass significantly increased at low and medium levels for uncovered treatment and medium level for covered treatment . Since a high amount of Cu was retained in leaf tissues but did not induce any toxic symptoms, lettuces likely employ a detoxification mechanism to build tolerance to excess Cu.

The [64Cu]-NP-uptake and accumulation amounts observed within lettuce seedlings were reasonable and comparable to others reports in the literature, reaching the same general conclusions that NP transport and accumulation in plants is species and size dependent.Smaller NPs have been demonstrated to have higher accumulation in plants than larger NPs. For example, Ni-NPs had very high NP uptake ranging from ∼13 200−38 983 μg/g in mesquite.The amount found in the leaves varied from 400 to 803 μg/g of mesquite with most the NPs remaining in the roots ranging from 12 835 to 38 183 μg/g.Another study using small CeO2-NPs exhibited NP accumulation ranging from 300 to 6000 μg/g of plant and indicated that NP accumulation was plant species dependent.NP sizes above active transport ranging from 14 to 40 nm had a large variation in uptake ranging from 0.25 to 3750 μg/g of plant, but typically had accumulation ranging from ∼1−1100 μg/g of plant again with the majority of the NPs contained within the root and with 0.5−183 μg/g in the leaves.NPs , had accumulation in mung bean of 8 μg/g and in wheat of 32 μg/ g.When comparing the accumulation of two similarly sized TiO2-NPs of different crystalline structure [22 nm and 25 nm ] in wheat different accumulation amounts were observed,vertical grow tables suggesting size was not the only limiting factor for transportation into a plant.In another study using radioactive NPs, Zhang et al.generated 141Ce by neutron bombardment of CeO2NPs synthesized via a precipitation method.

The fabrication of [ 141Ce]CeO2-NPs could make controlling the size distribution very difficult and the exact size of the radioactive [141Ce]CeO2- NPs was never determined. In addition, free radioactive 141Cemetal could dissolute and be transported into the plant, making it appear as if the intact-NPs were in the plant because possible leaching of radioactivity was not explored. We aimed to avoid complications of NP-fabrication in which the exact size distribution during the study could not be determined and to improve upon prior radio labeling methods, which gave low specific activity of 2.7 μCi/mg of NP.We were able to generate stable radioactive [ 64Cu]-NPs with high radio chemical purity and a specific activity of 2.2 mCi/mg of NP with a tight size distribution . Zhang et al.’s work also demonstrated a concentration and size dependence of the [141Ce]CeO2-NPs on plant accumulation in cucumber.These uptake differences may be attributed to the use of a different species and/or the NP solution administered had 2.4-times higher concentration . Autoradiography images showed [ 141Ce]CeO2-NPs movement to the leaves, implying that once NPs entered into the vascular cylinder, they move along with water flow. This was in good agreement with our study. In contrast, we saw no concentration dependence for either sized [ 64Cu]-NP using 48, 96, and 144 mg L−1 over a 2 h period with approximately the same accumulation amount at all concentrations . Similarly, another study using CuO-NPs administered two concentrations 10 mg L−1 and 100 mg L−1 for a period of 14 days in maize also observed no concentration dependence.

The use of NPs tagged with radioactivity and tracked by autoradiography and PET/CT has provided a noninvasive analytical tool to spatially visualize and quantify NP uptake and accumulation in plants. We investigated the fate of [64Cu]-NP transport into plants at the largely unexplored early time points, which would prevent dissolution events. Stability studies concluded that the [64Cu]-NPs were stable during the imaging and quantification time frame from 0.25 to 24 h resulting in intact NP-transport into lettuce seedlings. We further demonstrated that the transport of [64Cu]-NPs into lettuce was not concentration dependent but was size dependent with the 20 nm [64Cu]-NPs reaching a plateau with accumulation at ∼5.7 μg/g of lettuce and the smaller 10 nm NPs accumulation increasing linearly with the maximum amount at 24 h being ∼7.6 μg/g of lettuce.With the numerous factors that may dictate NP uptake and accumulation, further studies are warranted to fully understand the molecular mechanism of NP transport into plants.Legalization of cannabis production in 2017 has generated demands for state regulatory, research and extension agencies, including UC, to address the ecological, social and agricultural aspects of this crop, which has an estimated retail value of over $10 billion . Despite its enormous value and importance to California’s agricultural economy, remarkably little is known about how the crop is cultivated. While general information exists on cannabis cultivation, such as plant density, growing conditions, and nutrient, pest and disease management , only a few studies have attempted to measure or characterize some more specific aspects of cannabis production, such as yield per plant and regional changes in total production area . These data represent only a very small fraction of domestic or global activity and are likely skewed since they were largely derived not from field studies but indirectly from police seizure data or aerial imagery . In California, where approximately 66% of U.S. marijuana is grown , knowledge of the specific practices across the wide range of conditions under which it is produced is almost nonexistent.

Currently, 30 U.S. states have legalized cannabis production, sales and/or use, but strict regulations remain in place at the federal level, where it is classified as a Schedule I controlled substance. As a land-grant institution, UC receives federal support; were UC to engage in work that directly supports or enhances marijuana production or profitability, it would be inviolation of federal law and risk losing federal support. As a result, UC research on California cannabis production has been limited and focused on the geography of production and its environmental impacts . These studies have documented the negative effects of production on waterways, natural habitats and wildlife. While such effects are not unique to cannabis agriculture per se, they do present a significant threat to environmental quality and sensitive species in the watersheds where cannabis is grown . Science-based best management practices to mitigate or avoid impacts have not been developed for cannabis. Because information on cannabis production practices is so limited, it is currently not possible to identify key points of intervention to address the potential negative impacts of production. As a first step toward understanding cannabis production practices, we developed a statewide survey on cultivation techniques, pest and disease management, water use, labor and regulatory compliance. The objective was to provide a starting point from which UC scientists could build research and extension programs that promote best management practices — which are allowable as long as their intended purpose is not to improve yields, quality or profitability. Survey results also establish a baseline for documenting changes in cultivation practices over time as legal cannabis production evolves in California. To characterize key aspects of cannabis production in California,hydroponic growing systems we developed an anonymous online survey using Qualtrics survey software . A web-based survey that masked participants’ identity was determined to be the most suitable approach given that in-person interviews were limited by legal restrictions on UC researchers visiting cannabis farms, and mail or telephone surveys were constrained by the lack of any readily available mailing address or telephone contact information for most cannabis growers, who are understandably discrete with this information. An online survey was also the most cost-effective means of reaching a large number of cannabis growers. Survey questions focused on operational features , pest and water management, labor, farm revenue and grower demographics. Two draft surveys were reviewed by a subset of cannabis growers to improve the relevance of the questions and terminology. A consistent critique was that the survey was too long and asked for too much detail, taking up to 2 hours to complete, and that such a large time commitment would significantly reduce the response. We therefore made the survey more concise by eliminating or rephrasing many detailed questions across various aspects of cannabis production. The final survey included 37 questions: 12 openended and 25 structured . Structured questions presented either a list of answer choices or a text box to fill in with a number. Each list of answer choices included an “Other” option with a box for growers to enter text. Open-ended questions had a text entry box with no character limit. Condensing the survey to capture more respondents resulted in less detailed data, but the overall nature of the survey remained the same — a survey to broadly characterize multiple aspects of cannabis production in California. Data from the survey has supported and contextualized research by other scientists on specific aspects of cannabis production, such as water use , permitting , law enforcement , testing requirements , crop prices and perceptions of cannabis cultivation in the broader community . Recruitment of survey participants leveraged networks of California cannabis growers who had organized themselves for various economic and political purposes . These were a combination of county, regional and large statewide organizations, with many growers affiliating with multiple groups.

We identified the organizations through online searches and social media and sent recruitment emails to their membership list-serves. The emails contained an explanation of the survey goals, a link to the survey website and a message from the grower organization that endorsed the survey and encouraged members to participate. The emails were sent in July 2018 to approximately 17,500 email addresses, although not all members of these organizations necessarily cultivated cannabis, and the organizations noted that their mailing lists somewhat overlapped the lists of other groups that we contacted. For these reasons, the survey population was certainly less than 17,500 individual cannabis growers, but because we were not able to view mailing lists nor contact growers directly, and because there are no comprehensive surveys of the number of cannabis farms in California, we could not calculate a response rate or evaluate the representativeness of the sample. Respondents were given until Aug. 15, 2018, to complete the survey. All survey participants remained anonymous, and response data did not include any specific participant identifiers.In total, 101 surveys were either partially or fully completed. Responses to open-ended questions were coded before summary. Since incomplete surveys were included in this summary, the number of responses varied between questions. Each response was considered a unique grower and farm operation. As noted, survey response rate was difficult to quantify, and participants were self-selecting, which introduces bias. The survey data should be taken only as a starting point to guide more detailed evaluations of specific practices in the future, not as a basis for developing recommendations for production practices or policies.Survey respondents operated farms primarily in Humboldt , Mendocino and Nevada counties, but survey responses also came from Trinity , Santa Cruz , Sonoma , San Luis Obispo , Sacramento , Butte , Calaveras , Fresno , Los Angeles , San Diego , San Mateo and Siskiyou counties and Josephine County, Oregon . In line with California regulatory guidelines, small farms were defined as those of 10,000 sq ft or less, medium farms 10,001 to 22,000 sq ft and large farms 22,001 sq ft or more. Accordingly, 74% of farms were small, 16% were medium and 8% were large . For those growers who reported on their land use in 2013 , most farmed on land that was previously used entirely or in part for cannabis production . The other 22% indicated that the land was used in 2013 for agricultural crops, ranching, open space or “other” land uses.For this survey, we differentiated between outdoor , greenhouse and indoor farming . The most common ways to farm were all outdoors , combined outdoor and greenhouse and greenhouse only . This was followed by various combinations of greenhouse and indoor , greenhouse and other , outdoor and other , outdoor and indoor , all indoor and other . When measured by total plants, farms with combined outdoor and greenhouse facilities were responsible for 41% of crop production, followed by outdoor and other , greenhouse only , outdoor only , greenhouse and other , outdoor and indoor , greenhouse and indoor and other . A majority of survey respondents grew their cannabis crop in raised beds , native soil and/or grow bags , followed by hydroponic systems and plastic pots .Most growers reported groundwater as their primary water source for irrigation , with some growers reporting use of multiple water sources. Those using groundwater extracted 87% of annual volume between June and October. Of those storing water, most stored exclusively well or spring water, though some stored municipal water or rainwater .