No-tillage and high-residue practices reduce soil water evaporation

California Agriculture (UCANR) | April 1st, 2012

Reducing tillage and maintaining crop residues on the soil surface could improve the water use efficiency of California crop production. In two field studies co

Reducing tillage and maintaining crop residues on the soil surface could improve the water use efficiency of California crop production. In two field studies comparing no-tillage with standard tillage operations (following wheat silage harvest and before corn seeding), we estimated that 0.89 and 0.97 inches more water was retained in the no-tillage soil than in the tilled soil. In three field studies on residue coverage, we recorded that about 0.56, 0.58 and 0.42 inches more water was retained in residue-covered soil than in bare soil following 6 to 7 days of overhead sprinkler irrigation. Assuming a seasonal crop evapotranspiration demand of 30 inches, coupling no-tillage with practices preserving high residues could reduce summer soil evaporative losses by about 4 inches (13%). However, practical factors, including the need for different equipment and management approaches, will need to be considered before adopting these practices.

North Fork Kings Groundwater Sustainability Agency Groundwater Sustainability Plan (Revised)

North Fork Kings Groundwater Sustainability Agency (NFKGSA) | July 14th, 2022

North Fork Kings Groundwater Sustainability Plan

North Fork Kings Groundwater Sustainability Agency (NFKGSA) | December 18th, 2019

North Kings Groundwater Sustainability Groundwater Sustainability Plan

North Kings Groundwater Sustainability Agency | November 21st, 2019

Observational evidence of increased afternoon rainfall downwind of irrigated areas

Nature Portfolio (Springer Nature) | April 10th, 2025

Irrigation plays a vital role in addressing the growing food demand of an increasing global population. It represents one of the most critical and direct human interventi

Irrigation plays a vital role in addressing the growing food demand of an increasing global population. It represents one of the most critical and direct human interventions on the coupled water and energy cycles. As irrigated farmland continues to expand, understanding the climate impact of extensive irrigation becomes increasingly important. Yet, the effect on rainfall patterns near irrigated areas remains unclear. Here, using two global, high-resolution, sub-daily precipitation datasets, we show that afternoon rain events occur more often 10 km to 50 km downwind and less often upwind of extensively irrigated land. However, we also find that the total amount of heavy afternoon rain downwind of irrigated areas is lower than upwind. Our results establish large-scale observational evidence of the local precipitation dynamics surrounding irrigated areas; these insights will help constrain the representation of these processes in next-generation climate and weather forecasting models and provide valuable insights for regional water management.

Oil, Food, and Water: Challenges and Opportunities for California Agriculture

Pacific Institute | December 1st, 2015

A new comprehensive study by the Pacific Institute  sheds light on the risks posed when oil and gas exploration and production operate alongside agriculture. “There

A new comprehensive study by the Pacific Institute  sheds light on the risks posed when oil and gas exploration and production operate alongside agriculture. “There is growing concern about competition for land and water, and the impacts of soil and water contamination on the food supply and health and safety of farmworkers and consumers,” said Matthew Heberger, the study’s lead author. The disposal of oil and gas wastewater, which contains harmful chemicals, is a particular concern for agriculture. Disposal in unlined percolation pits poses a significant risk of contaminating groundwater resources that may, in turn, be used by agriculture. While this practice has been banned in several states, it is still widely used in California’s Central Valley, one of the nation’s most important agricultural regions. There are also serious deficiencies in the way California regulates the underground injection of wastes – current practices are not sufficiently protective of freshwater aquifers that may be used as drinking water or to irrigate crops and water livestock.

On-farm flood capture could reduce groundwater overdraft in Kings River Basin

California Agriculture (UCANR) | November 16th, 2016

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater rechar

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater recharge offers an opportunity to help address this challenge. We studied the infiltration rate of floodwater diverted from the Kings River at a turnout upstream of the James Weir onto adjoining cropland; and calculated how much land would be necessary to capture the available floodwater, how much recharge of groundwater might be achieved, and the costs. The 1,000-acre pilot study included fields growing tomatoes, wine grapes, alfalfa and pistachios. Flood flows diverted onto vineyards infiltrated at an average rate of 2.5 inches per day under sustained flooding. At that relatively high infiltration rate, 10 acres are needed to capture one CFS of diverted flood flow. We considered these findings in the context of regional expansion. Based upon a 30-year record of Kings Basin surplus flood flows, we estimate 30,000 acres operated for on-farm flood recharge would have had the capacity to capture 80% of available flood flows and potentially offset overdraft rates in the Kings Basin. Costs of on-farm flood capture for this study were estimated at $36 per acre-foot, less than the cost for surface water storage and dedicated recharge basins.

Paso Robles Subbasin Groundwater Sustainability Plan

Paso Robles Subbasin Cooperative Committee | November 13th, 2019

Paso Robles vineyard irrigation study provides benchmark data to assist future area groundwater management

California Agriculture (UCANR) | March 13th, 2018

Accurate information on irrigation water usage does not exist in many areas where groundwater is the primary water source. This lack of information will hinder

Accurate information on irrigation water usage does not exist in many areas where groundwater is the primary water source. This lack of information will hinder efforts to manage these groundwater basins sustainably according to current and future water regulations and policies. Using a low-cost methodology of irrigation-line pressure sensors connected to data loggers, we estimated irrigation applications at 84 vineyard sites in the Paso Robles Groundwater Basin over 4 years (2010–2013). We compared irrigation amounts with the preceding winter’s rainfall and with the growing season reference evapotranspiration (ETo). Over the study period, the average annual irrigation application was 11.46 inches (291 millimeters). The average annual application correlated inversely to the preceding winter’s rainfall, while the irrigation over the growing season (April–October) correlated directly with the ETo over this same period. This study provides an initial data framework that can be used by groundwater sustainability agencies to help manage groundwater in the Paso Robles area. The methodology also could be utilized in other regions to estimate regional irrigation usage while maintaining anonymity for participants.

Perceptions and responses to climate policy risks among California farmers

Global Environmental Change (Elsevier) | December 3rd, 2013

This paper considers how farmers perceive and respond to climate change policy risks, and suggests that understanding these risk responses is as important as understandin

This paper considers how farmers perceive and respond to climate change policy risks, and suggests that understanding these risk responses is as important as understanding responses to biophysical climate change impacts. Based on a survey of 162 farmers in California, we test three hypotheses regarding climate policy risk: (1) that perceived climate change risks will have a direct impact on farmer's responses to climate policy risks, (2) that previous climate change experiences will influence farmer's climate change perceptions and climate policy risk responses, and (3) that past experiences with environmental policies will more strongly affect a farmer's climate change beliefs, risks, and climate policy risk responses. Using a structural equation model we find support for all three hypotheses and furthermore show that farmers’ negative past policy experiences do not make them less likely to respond to climate policy risks through participation in a government incentive program. We discuss how future research and climate policies can be structured to garner greater agricultural participation. This work highlights that understanding climate policy risk responses and other social, economic and policy perspectives is a vital component of understanding climate change beliefs, risks and behaviors and should be more thoroughly considered in future work.