Evaluating effects of deficit irrigation strategies on forage sorghum attributes and nutrient composition grown in the San Joaquin Valley of California.

Jackie Atim (PI), UCCE Kearney REC, with Tobias Oker (UCCE), Robert Humacher (UC Davis/UCCE), and Nicholas Edward Clark (UCCE)

It is assumed that about 500,000 acres of irrigated cropland will be idled by 2040 under California’s Sustainable Groundwater Management Act. This will have broad impacts on the San Joaquin Valley (SJV) and its multibillion-dollar dairy industry. A major decision to face growers will be which crops to grow under constrained water supplies. This future raises the opportunity to identify forage sorghum varieties that can recover from drought and be grown sustainably and profitably with the required forage quality under limited irrigation capacities. The overall goal of this California Institute for Water Resources proposal is to develop production functions (i.e., the relationship between obtainable marketable yield and the total amount of water used by plant) for available commercial forage sorghum in the SJV and determine the threshold irrigation capacity for sustainable irrigated forage sorghum. This is a public-private collaboration aimed to provide key information on low irrigation capacities for forage sorghum and assess the effect of water allocation and use restrictions on forage biomass production and forage quality.