Concurrent Session 1A
Promises and Pitfalls: Adapting New Technology for Water Management--Subsurface Drip Irrigation in Alfalfa
Dan Putnam, UC ANR Cooperative Extension Specialist, Dept. of Plant Sciences, UC Davis
Abstract: Alfalfa is one of the largest acreage crop and key forage for the #1 agricultural enterprise in CA: dairy, an industry worth more than $7 billion/year. Alfalfa likely utilizes greater than 5 million acre-feet of water per year, and much of the crop is surface irrigated. While there are some advantages of surface irrigation systems (such as much lower energy costs, wildlife habitat, and groundwater recharge), there are important limitations. This crop has been roundly criticized for utilizing so much water using imprecise methods. Subsurface Drip Irrigation (SDI) is a known feasible alternative irrigation technology with superior application efficiencies that has been widely adapted in many crops, but not alfalfa. There are major potential benefits of drip irrigation: more precise water application methods, reduction in evaporation, improved distribution uniformity (over time and space), ability to more closely match ET and crop growth, improved ability to control nutrients, and eliminate surface runoff of pesticides carried in surface waters. Yield advantages of 19-35% more than flood irrigation have been reported from research trials and farmer’s fields for alfalfa, and some savings in water applications have been reported. However, there are major practical limitations of adaptation of SDI in alfalfa including cost, management, and rodent control. Currently less than 3% of California’s crop utilizes SDI, and some growers have given up on SDI due to these limitations. In this project, we have assembled a team to both test and improve the prospects of utilizing SDI in alfalfa, with trials both on UC stations as well as in grower’s fields. The aim is to address several of the limitations of the system. This project has a major outreach/engagement component, combining UC experiments with documented grower and industry experiences to build a state-wide knowledge base to assist growers in implementing SDI in alfalfa, solving problems such as management of rodents and irrigation scheduling. This project should have major policy implications, since, if successful, long-term strategies can be developed to increase water use efficiency in alfalfa, and if not successful, other strategies pursued.