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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Research Project #445622

Research Project: Developing Diversified and Climate Resilient Forage Systems for the Western U.S.

Location: Water Management Research

Project Number: 2034-21500-001-000-D
Project Type: In-House Appropriated

Start Date: Dec 21, 2023
End Date: Dec 20, 2028

Objective 1: Determine forage yield, water productivity and nutritional values of diversified forage systems under semi-arid conditions. Objective 2: Determine effects of irrigation and cutting schedule on forage yield, crop water productivity, stand persistence, and nutritional values of alfalfa varieties.

For Objective 1: The hypothesis to be tested under this objective is that alfalfa summer irrigation cutoff and the use of annual forage crops result in improved forage nutritive value and water productivity compared to traditional alfalfa production practices. Field experiments with four treatments will be carried out over five years. A reduced-lignin alfalfa and winter and summer annual crops will be planted. The experimental design is a randomized complete block with four replications. Plots will be irrigated using a flood irrigation system with each treatment having a separate zone equipped with a valve and a flow meter to allow precise irrigation applications. Initially, all treatments will be irrigated to achieve stand establishment. Irrigation will be applied to match crop ET requirement and maintain soil moisture content in the one to three feet soil depth at 18-30% level. Reference ET from a nearby weather station will be used to determine crop ET by multiplying with crop coefficient values from different growth stages after cuttings. Forage yield, quality, water productivity, and yield-quality relationships of alfalfa and annual forage crops will be determined in relation to the different forage systems. If high heat stress events occur in the first year of alfalfa production and survival of alfalfa in the summer irrigation cutoff treatment is in question, we will provide supplemental irrigation to prevent plant stand loss. For Objective 2: The hypothesis to be tested under this objective is that alfalfa forage yield is greater if cut every 35-days compared to 28-days under frequent sprinkler (FS) and simulated flood (SF) irrigations. Field experiments with FS and SF irrigation are planned for alfalfa varieties with reduced- and non-reduced lignin traits. The experimental design is a randomized complete block design with a split-plot arrangement with four replications. Irrigation/cutting schedule combinations and alfalfa varieties are main-plot and sub-plot treatments, respectively. The main-plot treatments are FS irrigation with a 35-day cutting schedule, FS irrigation with a 28-day cutting schedule, and one irrigation (SF) per harvest with a 28-day cutting schedule. Plots will be irrigated using an overhead sprinkler system. Each irrigation/cutting schedule treatment will be controlled separately using valves and water applied recorded with flowmeters. For FS treatments, irrigation will be applied weekly to match crop ET requirement. Similar reference ET and crop ET calculation approach and maintaining of soil moisture range and depths will be used as in Objective 1. Yield, quality, and plant biophysical parameters of alfalfa will be determined and analyzed to evaluate the interactive effect of irrigation frequency and varietal traits. If extreme weather events such as high heat stresses occur in treatment 3 that will lead to alfalfa stand loss, limited supplemental irrigation will be applied between harvests.