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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #401321
Research Project: Improving Soil and Water Productivity and Quality in Irrigated Cropping Systems

Location: Water Management Research

Title: Midsummer deficit irrigation of alfalfa for water conservation in the San Joaquin Valley of California

Author
item BALI, KHALED - Kearney Agricultural Center
item PUTNAM, DANIEL - University Of California, Davis
item Wang, Dong
item Begna, Sultan
item HOLDER, BRADY - University Of California
item MOHAMED, ABDELMONEIM - Kearney Agricultural Center
item PALOUTZIAN, LUKE - University Of California
item DAHLKE, HELEN - University Of California, Davis
item ELTARABILY, MOHAMED - University Of California, Davis

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2024
Publication Date: 12/1/2024
Citation: Bali, K., Putnam, D., Wang, D., Begna, S.H., Holder, B., Mohamed, A., Paloutzian, L., Dahlke, H.E., Eltarabily, M.G. 2024. Midsummer deficit irrigation of alfalfa for water conservation in the San Joaquin Valley of California. Journal of Irrigation and Drainage Engineering. 150(6). Article 04024029. https://doi.org/10.1061/JIDEDH.IRENG-10213.
DOI: https://doi.org/10.1061/JIDEDH.IRENG-10213

Interpretive Summary: Production of alfalfa in arid or semi-arid regions require irrigation, but the dependency on fresh water poses concerns under drought conditions. In a multiple- year study field experiments were carried out to evaluate deficit irrigation strategies during and after mid summer season for water savings. The research found that 50 to 70 percent water was saved with only 3 to 18 percent yield reduction. The findings provide farmers valuable information to balance water availability and alfalfa production for maximal economic returns.

Technical Abstract: Alfalfa is one of the major field crops in California, efficient irrigation management practices are necessary to cope with persistent droughts and limited water supplies. A four-year research experiment was conducted on sandy loam soil at the University of California Kearney Agricultural Research and Extension Center in Parlier, California to investigate the effect of mid-summer deficit irrigation on alfalfa yield, water use efficiency, and crop water productivity. Experiment was a randomized block design with two treatments: full and deficit irrigations with three replications. The deficit irrigation treatments were irrigated at the same time as the full irrigation treatments but water was turned off in August after the fifth cutting. Alfalfa was harvested every 28 to 40 days. Applied irrigation water was measured using a flow meter and soil matric potentials were monitored using Watermark soil moisture sensors. Actual evapotranspiration (ETa) values were measured by Tule Technologies (Link 1) and climatic data were obtained from a weather station at the research center. Results showed that 454.7, 704.3, 624.8, and 816.3 mm of irrigation water was saved when deficit irrigation was applied for years 2019, 2020, 2021, and 2022, respectively. These values represent 30.4, 40.9, 37.0, and 49.2 % of the applied water for the full irrigation treatment. When alfalfa was practiced under deficit irrigation, yield was reduced by 3.94, 2.04, 1.25, and 0.40 Mg ha-1 which equals to 18.1, 11.1, 7.1, and 3.0% of the yield for the full irrigation treatment for 2019, 2020, 2021, and 2022, respectively; with average reduction by 10.7% for the four years. Water use efficiency was higher when deficit irrigation was practiced than full irrigation treatment where it was 17.09, 16.11, 15.40, and 15.54 kg ha-1mm-1, for years 2019, 2020, 2021, and 2022, respectively. The production function using applied irrigation water (IW, mm) was: Y (yield in Mg ha-1) = 0.50 x (IW)2 – 1633.75 x (IW) + 1338472 and Y = –0.1137 x (IW)2 + 233.55 x (IW) – 103036 for the full and deficit irrigation treatments, respectively. Crop water productivity was 18.6, 16.4, 14.9, and 12.3 kg ha-1mm-1 for fully irrigated treatment, and 15.2, 14.9, 14.3, and 12.6 kg ha-1mm-1 for the deficit irrigation treatment, for 2019, 2020, 2021, and 2022, respectively. Our finding supports the water conservation practice in water-stressed conditions while during drought years, growers could utilize mid-summer deficit irrigation as a feasible strategy to maintain productivity and minimize the impact on profitability due to reduced water availability.