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Simulating alfalfa forage yields under full and deficit irrigation using the FARMs Web app in California

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  6th Decennial National Irrigation Symposium, 6-8, December 2021, San Diego, California  2020-009.(doi:10.13031/irrig.2020-009)
Authors:   Isaya Kisekka, Umair Gull, Daniel H Putnam
Keywords:   Alfalfa, Climate change, Irrigation, FARMs, Water, Central Valley California

Abstract. Alfalfa is one of the main forages utilized in dairy rations around the globe including the United States. Alfalfa production is threatened by constrained water supplies and climate change e.g., multiyear droughts. However, due to its deep-rooted characteristics, it can sustain long periods of drought. In this paper, we applied the online crop modeling tool called the Food, Agriculture, and Resource Management system (FARMs) to simulate alfalfa response to full and deficit irrigation regimes. FARMs simplifies crop modeling by automating the creation of input weather, climate, and soil data and adding geospatial capabilities. The online interface makes it convenient to select a field, create management practices and run crop models without requiring deep knowledge of software and database management. A fall dormancy 7 (FD 7) alfalfa variety was used in this study. Full irrigation (100% ET-Full) was applied following the crop evapotranspiration (ETc) for the entire season while deficit irrigation (60% ET-Cutoff) was fully irrigated until mid-summer and no water was applied after mid-July. Irrigation was applied using a linear move sprinkler irrigation system. The FARMs web app performed well with an R2 of 0.87 and an RMSE of 782.6 kg ha-1 for the alfalfa forage yield. The web app was able to simulate the crop water stress late in the season which corresponds well with the observed soil water content. Under changing climate and associated droughts, decision support tools like the FARMs web app may enable California growers to make optimum decisions for producing alfalfa with limited water supplies.

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