These efforts to manage groundwater supply and groundwater quality make the agricultural community subject to an evolving set of new requirements for documentation of key farm activities, training, practice improvement, monitoring and reporting. This will be a significant and in some cases expensive shift in farming practices. It is without parallel in California’s agricultural history. As was the case with the development and implementation of water quality regulatory programs in the 1970s through 1990s that targeted and significantly changed practices in industrial and urban land uses, the transition period will be challenging for this newly regulated community and likely take a generation to be fully effective. To the degree that a more centralized, region-wide effort — rather than a farm-by-farm approach — can direct the goals of these new programs, the ILRP coalitions will have a key role in providing services to help member farmers comply, at an annual cost currently ranging from about $3 to $7 per acre finding. Similar coordination and funding approaches may evolve within the GSAs that implement the new sustainable groundwater management legislation, with some additional funding available also through state and federal grants. But in addition to paying monitoring and compliance fees, farmers and their employees will also participate in training and continuing education, provided through the ILRP coalitions, local GSAs, UC ANR Cooperative Extension, National Resources Conservation Service, Resource Conservation Districts and others; and on many farms, significant infrastructure improvements are needed to address groundwater quality and quantity concerns, at significant cost to the farm operation finding. This is not a transition period only for farmers; it is also a transition period for scientists and educators who develop and provide innovative management practices and training to protect groundwater quality and better understand the groundwater–agriculture interface.
Agronomic and crop scientists have rarely taken into account losses of contaminants to groundwater when developing best management practices and farm recommendations. Existing recommendations for fertilizer applications, for example,vertical growing towers are in urgent need of revision to account for potential unwanted losses of nutrients to groundwater finding. Another challenge for scientists is the design of groundwater monitoring networks. Existing groundwater research has developed many approaches to monitoring distinct contaminant plumes, typically a few acres in size finding, but recommendations for the design of non-point source monitoring networks are currently lacking finding. Furthermore, this is a transition period for regulatory agencies, which for the first time are regulating non-point sources of groundwater pollution that involve large tracts of land with numerous individual landowners who are adjacent to each other and a wide range of crops, soils and management practices. For agencies, this is a situation that requires innovative strategies and a significant rethinking of existing programs that have been focused on point sources or surface water quality. For example, regulatory agencies have long focused on shallow groundwater monitoring wells as a key tool for monitoring potential waste discharges into groundwater and to detect inadvertent contaminant plumes from point sources, such as from underground gasoline storage tanks. Underground storage tanks are discrete point sources, and leaks from them can be detected by using down-gradient monitoring wells finding. Agricultural irrigation, in contrast, leaks by design across broad landscapes, to flush salts from the root zone. Agricultural irrigation has therefore also been a significant source of groundwater recharge, especially irrigation from older non-efficient systems.The specific monitoring requirements under each of the three tracks are a function of groundwater conditions, potential pollution sources, proximity to public and private water supply wells and existing contamination.
The role of the groundwater assessments described above is to better understand these aquifer conditions as a basis for developing these three-tracked monitoring programs effectively, efficiently and commensurate with groundwater vulnerability.Managing groundwater quantity in California’s diverse agricultural landscape is intricately linked to protecting groundwater quality and vice versa. New practices in the agricultural landscape to recharge clean water into aquifers while maintaining high irrigation efficiencies and while also controlling nutrient and pesticide leaching will address both groundwater overdraft and groundwater quality. Dzurella et al. finding and others have outlined numerous ways to improve nutrient management in California’s diverse cropping systems, following largely the concept of the Four Rs: Right amount, Right time, Right place, Right form finding. Significant educational efforts by universities, state and federal agencies, and industry groups will need to continue and intensify to support agriculture in moving forward with practices that better protect groundwater. There is one key complication around managing nutrients: while high nutrient-use efficiency reduces nitrate and pesticide loading, it also is typically achieved only with high water-use efficiency. In situations where irrigation water is imported to the groundwater basin rather than pumped from local aquifers, higher water-use efficiency translates into significant reductions in groundwater recharge, impacting long-term water supplies and raising the need for additional recharge of clean water. New agricultural practices, yet to be developed, also promise to play an important role in simultaneously addressing groundwater quality and groundwater quantity issues: the agricultural landscape potentially provides a wide range of opportunities for using floodwaters and other surplus surface water to recharge groundwater, whether with recharge basins, field flooding, targeted clean recharge irrigations or other methods finding. The significant potential for innovation and field testing in this arena could lead to water being intentionally recharged in the agricultural landscape without degrading water quality, possibly even improving water quality.
For example, in areas recharging groundwater for public supply wells finding, some nitrogen-intensive crops may be replaced with crops that are known to be relatively protective of groundwater quality. This has been shown to be an economically promising option to address long-term drinking water quality issues, especially in the source area of drinking water supplies for small, often disadvantaged communities finding. More research and pilot testing are needed.Groundwater management cannot be done without managing surface water resources. The future of groundwater use, protection and management in California’s agricultural landscape will be an increasingly integrated approach to managing the quality and quantity of both surface water and groundwater. Land-use planners must also be more involved in and informed by water planning and assessment activities. New regulations for groundwater sustainability and groundwater quality protection have emphasized the engagement of landowners and local stakeholders in the planning and implementation of new regulations, providing stakeholders, including farmers, with opportunities for engagement, dialogue and education. Integration of the new groundwater regulations with existing programs in integrated regional water management finding planning and urban water management planning will be needed. This integrated strategy will employ a diverse portfolio of approaches reflecting local needs, local technical and economic capacity, and the diversity of local stakeholders and of their engagement in these efforts.The share of hired agricultural workers who migrate within the United States plummeted by almost 60% since the late 1990s. This paper is the first to document and systematically analyze this drop in the migration rate. We estimate annual models of crop workers’ migration decisions for 1989 through 2009. Based on these estimates, we decompose the change in the migration rate into two causes: shifts in the demographic composition of the workforce and changes in coefficients .
During the same period as the migration rate decreased, the total number of farm workers fell.The combination of these two effects has substantially reduced the ability of farmers to adjust to seasonal shifts in labor demand throughout the year, leading to crises in which farmers report not being able to hire workers at the prevailing wage during seasonal peaks.As the academic literature shows, labor migration can temper the effects of macroeconomic shocks that vary geographically and the effects of industry restructuring such as those arising from the decline of manufacturing . The demographic composition of the agricultural work force has changed substantially since 1998. For example, the average worker today is older, more likely to be female, and more likely to be living with a spouse and children in the United States. We hypothesized that such workers might be less likely to migrate. We test various hypotheses and find that demographic changes played an important role in reducing the migration rate alongside underlying structural changes.The first section discusses U.S. and Mexican institutional, governmental, and economic changes during our sample period that affected the demographic composition of the agricultural workforce and the migration of workers. The next section describes our data set, provides summary statistics, and plots trends in migration rates over time. The third section presents the estimates of the migration choice model for various years. The fourth section decomposes the drop in the migration rate into changes due to shifts in the means of demographic variables, holding the model’s structure constant,container vertical farming and changes in the estimated coefficients, holding the means of the demographics constant. The fifth section shows how changes in the mean of individual demographic characteristics contributed to the decline in the migration rate. The last section summarizes our results.A number of institutional, governmental, and economic changes contributed to the reduction in the migration rate within the United States directly or through their effects on the demographic composition of the workforce. These shocks affected the supply and demand for labor in both Mexico and the United States.
At about the time that the migration rate started to fall in the late 1990s, many institutional changes occurred in the United States and Mexico that affected the ease of crossing the U.S.-Mexican border and the desire of Mexican nationals to cross. Several new U.S. laws and additional funding for border enforcement made crossing more difficult: the Illegal Immigration Reform and Immigrant Responsibility Act of 1996, the Homeland Security Act of 2002, the USA Patriot Act of 2002, the Enhanced Border Security and Visa Entry Reform Act of 2002, the Intelligence Reform and Terrorism Prevention Act of 2004, the REAL ID Act of 2005, and the Secure Fence Act of 2006. According to a survey of migrants, the cost of crossing the border with the help of smugglers, or “coyotes,” rose substantially since mid-1990s.Cornelius notes that increasing coyote costs are associated with decreases in the probability of returning to a country of origin and with increases in deaths along the border.Newspaper articles indicate that the U.S. government substantially increased U.S.-Mexican border enforcement since the mid-2000s. In addition, changes in U.S.-Mexican foreign relations and in Mexican public policy reduced incentives for its citizens to move to the United States in the second half of our sample period . Mexican farm laborers were less like to migrate to the United States because of increased economic growth in Mexico, rising productivity, and decreased birth rates . The 1997 anti-poverty Programa de Educación, Salud y Alimentaciónin Mexico increased welfare in Mexico through education, health, and conditional cash transfer initiatives, which decreased the incentive for workers to cross the border . Oportunidades also increased agricultural production in Mexico . Changes in the legal status of farm workers also affected the U.S. farm labor force. For example, the 1986 Immigration Reform and Control Act conferred legal status on many previously unauthorized workers, which provided a path to a legal permanent residence status and citizenship. By so doing, IRCA reduced the share of unauthorized workers during the 1990s. Over time, many of these workers left agriculture. Together, these factors reduced the number of undocumented workers from Mexico in the United States. Martin reviews the history of immigration legislation and domestic enforcement and concludes that the e-verify program had little impact during the period immediately after IRCA went into effect. In contrast, Kostandini, Mykerezi and Escalante show that after 2002, counties participating in the Department of Homeland Security’s 287 enforcement program had fewer foreign-born workers, reduced labor usage, and experienced changes in cropping patterns among producers. In our empirical analysis, we investigate whether the willingness of a worker to migrate within the United States depends crucially on legal status. A variety of other structural factors also affected the supply and demand for U.S. farm labor. In recent years, increased consumer demand for fresh fruits and vegetables and expanded exports of agricultural commodities led to greater production of labor-intensive crops .