California produces more than 400 different crops and accounts for over a third of the country’s vegetables and about two-thirds of its fruits and nuts. The state’s combination of Mediterranean climate, engineered water systems, and rich soils turned its Central Valley into one of the most productive agricultural regions on earth. But that productivity sits on top of a stack of escalating pressures, from chronic groundwater depletion and sinking land to warming winters that threaten the tree crops the state is famous for.
What Grows Where, and Why It Matters
California’s crop geography divides roughly by latitude and water access. The Sacramento Valley in the north grows rice, tomatoes, and other field crops that rely heavily on surface water from the Sacramento River system. The San Joaquin Valley in the south is the heartland of almonds, pistachios, walnuts, grapes, and citrus, crops that depend more on a mix of surface deliveries and groundwater pumping. Along the coast, cooler microclimates support strawberries, leafy greens, and wine grapes, while the Imperial Valley in the far south produces winter vegetables under desert heat with Colorado River water.
Tree nuts have reshaped the state’s agricultural landscape over the past two decades. Almond acreage alone exceeded one million bearing acres by 2017, and that expansion pulled enormous resources along with it. California’s almond orchards require roughly two million honeybee hives every February for pollination, which amounts to nearly 70 percent of all commercial hives in the country. Pollination fees per hive almost tripled in inflation-adjusted terms between the mid-1990s and the late 2010s, generating around $340 million annually for the beekeeping industry, a figure comparable to total U.S. honey revenues.1Oxford Academic. Pollination Markets and the Coupled Futures of Almonds and Honey Bees: Simulating Impacts of Shifts in Demands and Costs That single crop’s dependence on a single pollinator underscores how tightly California agriculture is wired to ecological services that are themselves under stress.
The Water Equation
Water is the central constraint on California farming, and the numbers vary dramatically by crop. A study of the Central Valley found that rice consumed about 1,110 millimeters of water per year with little variation from field to field, while pistachios averaged only 592 millimeters but varied by nearly 60 percent depending on orchard age and location. Almonds fell in between at roughly 964 millimeters, and walnuts at about 981 millimeters.2PubMed Central. Multiscale Assessment of Agricultural Consumptive Water Use in California’s Central Valley Those differences matter when regulators and farmers weigh which crops to keep irrigating during droughts and which to let go.
Drip irrigation, which delivers water directly to plant roots instead of flooding whole fields, has been a major efficiency gain. Its adoption in California unfolded over more than four decades and required the technology to co-evolve with crop-specific growing methods. Success depended on collaboration between private companies and public agricultural researchers working at the local level to adapt drip systems to everything from vineyards to vegetable rows.3Oxford Academic. Diffusion of Drip Irrigation: The Case of California Even with those advances, California’s aquifers have been chronically depleted. The state enacted the Sustainable Groundwater Management Act (SGMA) to halt the decline, and meeting its targets could mean taking roughly half a million hectares of irrigated farmland out of production.4Frontiers in Water. Cropland repurposing as a tool for water sustainability and just land transition in California: review and best practices
That kind of land retirement is not hypothetical. In Kern County, one of the state’s top agricultural producers, stakeholders have already described a shift toward perennial tree crops and vines on remaining irrigated land, partly because those crops generate more revenue per unit of water. But the transition also increases financial costs and squeezes out lower-value field crops.5Regional Environmental Change. Sustainable groundwater management and its implications for agricultural land repurposing Farmers planting a permanent orchard are making a 20-to-25-year bet that water will be available for the life of those trees, a gamble that gets riskier as aquifer levels keep dropping.
The Ground Literally Sinking
Decades of heavy groundwater pumping in the San Joaquin Valley have caused the land surface to sink, a process called subsidence. Between 2006 and 2022, the valley lost about 14 cubic kilometers of volume to subsidence, matching the total measured during a 24-year period in the mid-twentieth century but compressed into just 16 years. The average annual rate more than doubled compared to the historic period.6Communications Earth & Environment. Quantification of record-breaking subsidence in California’s San Joaquin Valley
The sinking is not evenly distributed. Cultivated land experienced up to seven times the total subsidence of uncultivated land between 2015 and 2017, and during dry years the gap widened further, with farmland sinking at up to nine times the rate of fallow ground. On uncultivated areas, subsidence barely changed between wet and dry years. On cultivated areas, dry-year sinking rates were more than double wet-year rates, a clear signal that farmers pump harder when rain and surface deliveries fall short.7Environmental Research Letters. Fine-scale spatiotemporal variation in subsidence across California’s San Joaquin Valley explained by groundwater demand The consequences are tangible: buckled canals, cracked roads, and reduced capacity in the very aqueducts that deliver surface water. Subsidence, in other words, damages the infrastructure that would reduce the need for pumping.
Salt in the Soil
Even where land is not sinking, salt buildup quietly erodes productivity. Irrigation water carries dissolved minerals, and as water evaporates or is taken up by plants, those salts concentrate in the soil. A model of the San Joaquin Valley found that although total salt inputs and outputs were roughly balanced over a 20-year span, salts were progressively moving into deeper aquifers, raising questions about the long-term sustainability of irrigated farming in the region.8PubMed Central. Sustainability of irrigated agriculture in the San Joaquin Valley, California
The economic toll is already substantial. High-resolution modeling estimated that soil salinity reduced California’s agricultural revenues by about $3.7 billion in 2014 alone, with a plausible range from $1.7 billion to $7.0 billion, and caused roughly 8 million tons of lost crop production.9Environmental Research Letters. High-resolution model for estimating the economic and policy implications of agricultural soil salinization in California The same study found that using coarser data underestimated those costs by a factor of three, which means the problem has likely been systematically undercounted in earlier assessments. Salt damage is not equally distributed across crops. Sensitive fruit and nut trees suffer yield losses at salinity levels that field crops tolerate, adding yet another pressure on the high-value orchards the state’s economy depends on.
Warming Winters and Disappearing Chill
Most temperate fruit and nut trees need a certain number of cool winter hours to flower properly in spring, a requirement known as winter chill. As California’s winters warm, those hours are vanishing. Models project that mean winter chill across Central Valley sites will drop by roughly 14 to 33 percent between 1950 and 2050, depending on which chilling metric is used.10Agriculture, Ecosystems & Environment. Sensitivity of winter chill models for fruit and nut trees to climatic changes expected in California’s Central Valley For crops like cherries, walnuts, and certain stone fruits that need long, cold winters, the decline could push viable growing zones northward or force growers to switch to low-chill varieties that may not command the same market prices.
Rising temperatures also intensify wildfire seasons, which creates a unique problem for wine grapes. When smoke drifts over vineyards, volatile compounds from the fire penetrate grape skins and become chemically trapped inside the berries. In that bound form, the compounds are odorless and tasteless in the fruit. But during fermentation and aging, they release, producing unmistakable smoky, ashy flavors that ruin the wine.11American Journal of Enology and Viticulture. Changes in Smoke-Taint Volatile-Phenol Glycosides in Wildfire Smoke-Exposed Cabernet Sauvignon Grapes throughout Winemaking The problem is insidious because growers often cannot tell at harvest whether their fruit is tainted; the defect only becomes obvious later. In bad fire years, entire vintages have been rejected or declassified, costing individual wineries hundreds of thousands of dollars.
Farmworker Heat Exposure
The same warming climate that threatens tree crops also threatens the people who tend them. California has some of the most protective heat-illness regulations for outdoor workers in the country, including mandated shade, water access, and rest breaks. Yet field research has found that heat-related illness risk remains elevated even on farms that follow those rules, because work intensity and environmental temperatures can overwhelm the protections in place.12PubMed Central. Are Cal/OSHA Regulations Protecting Farmworkers in California From Heat-Related Illness?
The problem runs deeper than thermometers. A study of California’s Imperial and Coachella valleys, two of the hottest farming regions in the state, found that heat risk is structurally produced. Workplace power dynamics, economic precarity, and fear tied to immigration enforcement all discourage workers from reporting symptoms or taking breaks. The researchers described extreme heat not simply as an environmental hazard but as an occupational health hazard shaped by social and institutional forces.13Journal of Rural Studies. Heat, health, and enforcement: A multi-level qualitative analysis of extreme heat, work conditions, and structural vulnerability in California’s desert agriculture As summer peak temperatures continue to climb, the gap between regulatory intent and on-the-ground reality is likely to widen.
Pest Threats to Citrus and Grapes
California’s warm climate and enormous acreage of high-value crops make it a magnet for invasive pests. Two stand out for their potential to reshape the state’s agriculture.
The Asian citrus psyllid, a tiny insect that transmits the bacterium responsible for huanglongbing (also called citrus greening disease), was first detected in California in 2008 and has been spreading through residential citrus trees in Southern California ever since. The disease has been confirmed in the Los Angeles area since 2012 and continues to move through backyard plantings.14PubMed. Geospatial Risk-Based Survey Model for ‘Candidatus Liberibacter asiaticus’ Detection in Residential Citrus Populations in California There is no cure for infected trees. Regulators responded by mandating insecticide treatments for citrus nursery stock and limiting how long host plants can sit at retail garden centers, attempting to slow human-assisted spread through the movement of potted citrus.15Crop Protection. Assessing the risk of containerized citrus contributing to Asian citrus psyllid (Diaphorina citri) spread in California The commercial citrus industry, worth several billion dollars annually, faces a genuine existential scenario if the disease breaches its containment in residential areas and enters the groves of the San Joaquin Valley at scale.
The glassy-winged sharpshooter, a large leafhopper that spreads the bacterium behind Pierce’s disease in grapevines, presents a different kind of headache. Populations in Kern and Tulare counties have developed high levels of resistance to imidacloprid, the neonicotinoid insecticide that has been the main chemical tool against them. Researchers also detected lower but meaningful cross-resistance to other insecticide classes. Even sharpshooters collected from organic citrus groves, where neonicotinoids are not applied directly, showed high imidacloprid resistance, suggesting the resistance genes are widespread in the regional population.16Pest Management Science. Insecticide resistance in California populations of the glassy-winged sharpshooter Homalodisca vitripennis Losing the primary chemical control for a disease vector with no treatment for the disease itself is the kind of quiet crisis that rarely makes headlines until the damage is done.
Export Bottlenecks and Trade Vulnerability
California’s crops do not just feed the domestic market. The state is a major agricultural exporter, especially for tree nuts, dairy products, and wine. That export engine runs through the ports of Los Angeles and Long Beach, which means it is vulnerable to shipping disruptions. During the supply chain crisis of 2021, port congestion and container shortages reduced California’s containerized agricultural exports by about 22 percent from May through November. The losses exceeded $3.2 billion, and tree nut producers bore the heaviest financial impact.17Applied Economic Perspectives and Policy. Supply chain disruptions and containerized agricultural exports from California ports
Tree nuts are particularly exposed because they are high-value, time-sensitive exports shipped primarily in refrigerated containers. When containers were unavailable or ships were backed up for weeks, buyers in Asia and Europe turned to other suppliers. Some of that market share has been slow to return. The episode laid bare how a state that dominates domestic production of many crops can still be fragile in the face of logistics failures that have nothing to do with farming itself.
Organic Farming and Cover Crops
Organic agriculture in California is smaller than many people assume. As of 2022, only about 4.5 percent of the state’s cropland was certified organic, even though California leads the nation in total organic crop acreage at just over 430,000 acres. By contrast, about 11.4 percent of acreage used for animal production (primarily rangeland) carried organic certification.18California Agriculture. New estimates show the first decline in California’s organic share of cropland Recent estimates show that the organic share of cropland actually declined for the first time, a trend driven in part by rising costs, water constraints, and the difficulty of converting permanent plantings like nut orchards to organic management.
One sustainable practice gaining traction regardless of organic certification is winter cover cropping. Instead of leaving fields bare between cash crop seasons, growers plant species like legumes or grasses to hold the soil. Research in the Sacramento Valley found that cover-cropped plots produced consistently less runoff than fallow fields and stored more water in the top meter of soil once the ground was saturated. The key was terminating the cover crop before it consumed that extra stored moisture through its own evapotranspiration.19Transactions of the ASAE. Infiltration and Soil Water Storage under Winter Cover Cropping in California’s Sacramento Valley Cover crops also reduce erosion, suppress weeds, and build soil organic matter, benefits that compound over years even when they are hard to monetize in a single season.
Experimental Crops for an Arid Future
If water scarcity continues to tighten, some researchers are looking beyond traditional California crops entirely. A field trial in the state’s arid lands tested agave, the succulent used to make tequila in Mexico, as a potential bioenergy feedstock. After three years, healthy plants of one species produced about 9.3 metric tons of dry mass per hectare per year with only 530 millimeters of total annual water input, including rainfall. Yields were lower than earlier projections, but the water requirement was substantially less than what conventional irrigated crops in the Southwest demand.20GCB Bioenergy. Productivity and water use efficiency of Agave americana in the first field trial as bioenergy feedstock on arid lands
Agave is not about to replace almonds or lettuce. But the trial illustrates a broader shift in thinking. As groundwater regulations force hundreds of thousands of acres out of irrigated production, some of that land could support drought-adapted crops that generate biomass for energy, fiber, or industrial uses rather than sitting idle. Whether growers adopt such alternatives depends on whether markets develop for those products, a chicken-and-egg problem that no amount of agronomic research can solve on its own.