Water Resources Research Act Program

Details for Project ID 2018CA377B

Water and nitrogen use efficiencies of sub-surface drip irrigated and fertilized forage corn and sorghum in the San Joaquin Valley of CA

Institute: California
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $14,006 Total Non-Federal Funds: $3,642

Principal Investigators: Nicholas Clark

Project Summary: Yield potentials of forage corn and sorghum under different N fertilization and irrigation levels have been characterized in a number of past studies in California and other western states. What remains unknown are the yield potentials of forage sorghum under the higher levels of irrigation and N fertilization, such as those traditionally considered optimal for forage corn, under sub-surface drip irrigation. This study aims to answer the questions of relative yield potential and feed quality of forage sorghum under comparable conditions as corn. This study will be conducted at the West Side (WSREC) and Kearney (KAREC) research and extension centers over two years. Varieties of corn tested will include one early and one later maturing cultivar, and sorghum varieties will include at least a compact, brachytic type, a dual purpose forage/grain type, and a tall, photoperiod sensitive type. Irrigation levels will reflect full crop evapotranspiration (ETc) for sorghum (21-22 inches) and for corn (28-32 inches) and deficit irrigation (16-18 inches). Nitrogen treatments will be optimal for corn (250-275 lbs N/acre) and sorghum (100-120 lbs N/acre) and a 0 lbs N/acre control. Total plant N removal will be estimated using above ground plant harvests and N analyses, and estimates of changes in soil residual nitrate-N will be estimated using pre-plant and post-harvest soil nitrate-N measurements up to eight feet in depth. ETc will be estimated using applied water measurements plus changes in measured gravimetric soil water content pre-plant and post-harvest. Yield components measured will be silage harvest weights, digestible fiber, %DM, and crude protein.