- (Strategic Initiative) Water Quality, Quantity, and Security
- Author: Ali Montazar
UC ANR research helps Southern California farmers conserve water by an average of 15% and encourages others to make region-specific crop management and irrigation decisions, contributing to UC ANR's public value of protecting California's natural resources.
Water scarcity will become a more significant concern in the Colorado River Basin due to altered weather patterns and multi-year droughts. Knowledge of the evapotranspiration (ET) of crops produced in Southern California will be critical to better managing limited water resources. Accurate information on crop water use and crop coefficient (Kc) is an immediate need for on-farm water conservation programs in the low desert region. Growers, irrigation and water districts, and researchers typically use crop coefficients developed in the Central Valley or other areas. Formulating this irrigation information for the Southern California region is crucial since the region has differences in climate, soil types and conditions, cropping systems, and irrigation and farming practices.
How UC Delivers
Extensive field measurements were conducted in 53 commercial fields over the last three-year for 11 agricultural commodities, including alfalfa, carrots, onions, Klein grass, date palm, lemons, olives, sugar beets, spinach, sunflowers, and wheat. The residual of energy balance method, which used a combination of surface renewal (SR) and eddy covariance (EC) techniques, was used to determine the actual ET and crop coefficients in each site. In addition, Tule technology, an affordable crop water use measurement sensor, was set up at the experimental sites for extension purposes. Twenty fully automated SR-EC ET towers, 60 Tule technology sensors, and more than 700 other various soil moisture sensors were set up in the Imperial, Coachella, and Palo Verde valleys. The study's crop coefficients and irrigation management best practices were periodically shared with cooperative growers to evaluate their practices, learn about the advantages of sensor-based irrigation management, and encourage utilizing the tools and information to improve irrigation management and yield production. Additionally, the information was discussed with local irrigation and water districts in different events and meetings, and study findings were published in several extension articles and peer-reviewed journals.
As a result of collaborating in this study, a cooperative date grower found that water use efficiency improved by 18%, puffy skin diseases of date fruits reduced, and fruit quality improved overall. The study, which includes nearly 50% of crops grown in the region, helped participating growers conserve water by 15% on average across various agricultural commodities. Furthermore, these findings provide evidence about the benefits of the residual of energy balance method, water use sensors, and soil moisture sensors specifically in southern California. The most accurate crop coefficients for the cropping systems and the best factual guidance available provide significant benefits to the region by supporting enhanced water and nutrient use efficiency and drought resilience information for profitable and sustainable crop production. The tools developed by this program have the potential to yield large dividends through not only improved resource use efficiency but also best management practices and crop quality. Local irrigation and water districts may utilize the information in their on-farm efficiency conservation and water delivery programs. Additionally, adopting these knowledge-based information and tools in combination with CIMIS (California Irrigation Management Information System) or Spatial CIMIS data may benefit the region more than $7.5 million in water and energy savings.
These outcomes demonstrate UC ANR's public value of protecting California's natural resources. The following links are publications associated with this study that have been shared in agricultural journal and research settings:
- Author: Ali Montazar
UC ANR research on drip irrigation shows potential to reduce downy mildew incidence while improving water quality and resource-use efficiency, contributing to increased water-use efficiency and improved food safety.
Spinach is a leafy green quick-maturing, cool-season vegetable crop. Downy mildew on spinach is a widespread and very destructive disease in California. It is the most significant disease in spinach production, causing crop losses in all areas where spinach is produced. Most conventional and organic spinach fields are irrigated by solid-set or hand-move sprinklers. However, overhead irrigation may contribute to the speed and severity of downy mildew epidemics within a field when other conditions such as temperature are favorable. It is postulated that new irrigation management techniques and practices in spinach production may have a significant economic impact to the leafy greens industry through the control of downy mildew.
How UC Delivers
The main objective of this study was to explore the viability of adopting drip irrigation for organic and conventional spinach production. Field experiments were conducted at the UC Desert Research and Extension Center and three commercial fields in the low desert of California over four crop seasons (2018-2021). Several treatments and comprehensive data collection were carried out to optimize drip system design, irrigation and nitrogen management strategies, planting method, and evaluating the effects of drip on plant growth and downy mildew incidence, and seed germination by drip irrigation.
The results of this multi-year study demonstrated that drip irrigation has the potential for producing profitable spinach in the California crop production system. No significant yield difference was observed among sprinkler treatments and most drip treatments in the 2021 trial. An overall effect of the irrigation system on downy mildew was observed, in which downy mildew incidence was two-to-five times lower in plots irrigated by drip when compared to sprinklers. The likely mechanism for reducing downy mildew incidence is the reduction in leaf wetness resulting from drip irrigation. Leaf wetness is a critical factor for infection and sporulation by the downy mildew pathogen.
The findings of the aforementioned study show that adopting drip irrigation for high-density spinach plantings can reduce incidence of downy mildew and related food safety risks and crop loss. As a result of participating in research trials, a cooperative grower reported a considerable cost reduction of $300 per acre due to less/no water treatment applications for downy mildew control and food safety issues in conventional spinach under drip irrigation. The findings of this study show that adopting drip irrigation for high-density spinach plantings can be a solution to reduce food safety risks and losses from downy mildew, conserve water and fertilizer, and reduce greenhouse gas emissions. A lower energy cost of $200 per acre is estimated for spinach producing under drip irrigation.
Several factors influence appropriate drip irrigation management in spinach including system design, soil characteristics, and environmental conditions. Drip irrigation offers the potential for precise water management, as well as the ideal vehicle to deliver nutrients in a timely and efficient manner. However, achieving high water- and nutrient-use efficiency, while maximizing crop productivity requires intensive and proper management, particularly in organic baby spinach. The knowledge-based information and findings of this study have been shared with growers and stakeholders through several media interviews, presentations in workshops/webinars, and extension and peer-review publications, contributing to UC ANR's public values of resource conservation and safe, sufficient food for all. The following links are some of the publications associated with this study in Western Farm Press, the Desert of Review, the Holtville Tribune, California Ag Today Radio, Vegetables West, California Organic Farmer, Journal of Agriculture, Agricultural Briefs, and UC ANR Knowledge Stream: