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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Research Project #435241

Research Project: Improving the Efficiency of Alfalfa Irrigation in the Great Plains Region with Subsurface Drip Irrigation

Location: Water Management Research

Project Number: 2034-13210-001-02-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 30, 2018
End Date: Sep 30, 2022

Objective:
Develop and improve irrigation strategies to increase water use efficiency in alfalfa production in the Great Plains area.

Approach:
Research field trials will be conducted at Kansas State University Northwest Research-Extension Center at Colby, Kansas. Trials will focus on trying to optimize alfalfa production with highly efficient subsurface drip irrigation (SDI). Additional field research efforts will test deficit irrigation strategies such as certain percentages of ET-Rain replacement which is possible in the semi-arid Great Plains with summer pattern precipitation. Another effort at improving irrigation efficiency for alfalfa will concentrate on water applications during specific summer growth periods with the goal of optimizing production during the more productive periods (e.g., less hot and less ET). Allowing reduction of alfalfa production with deficit irrigation will result in variations in alfalfa quantity and quality with distance from the subsurface dripline, so this will require multiple samples from each research plot to characterize this aspect. A machine harvester will be used to harvest multiple samples at specified distances from the center of the dripline. Additional field sites will be considered as appropriate, such as USDA Agricultural Research Service at Bushland Texas, in growers’ fields, or other Kansas State University Research and Extension facilities where soil characteristics and/or climatic conditions are different. Soil physical and chemical properties will be characterized for each site. Measured parameters will include bulk density, soil water retention curves, particle size distribution, pH, CEC, and nitrogen, phosphorus, potassium contents. Because alfalfa is a deep rooted crop, measurements will be made at 15, 30, 50, 100, 200, and 300 centimeter depths. Soil water content will be determined periodically (i.e., weekly to once every 2 weeks) with the neutron attenuation method to a depth of 3 meters and using moisture sensors buried at the selected depths and recorded at hourly intervals for the entire duration of the study. Because multiple irrigation treatments are used, these soils and water content measurements will also need to be made individually for each treatment. These measurements will be used in soil physics modeling of water movement under the different variations of SDI to determine the optimal depth for SDI placement and soil water conditions for alfalfa growth. Response variables will also include alfalfa yield and quality. All data will be statistically analyzed. Upon completion, this project will improve irrigation management for alfalfa production in the region. The project findings will be presented at annual alfalfa conferences and professional meetings as well as distributed through extension activities. Kansas State University has an extensive website devoted to crop management with subsurface drip irrigation, “SDI in the Great Plains” http://www.ksre.k-state.edu/sdi/. New findings on improving alfalfa irrigation efficacy using SDI will be added to the website.