A three-year university research project launched this fall in farm cooperator fields in Southern California and southwestern Arizona will study preplant variable rate applications of phosphorus (P) in commercial winter vegetable production.

The findings could not only help vegetable growers more precisely apply P, reduce P use overall, and increase yields which combined could increase grower profitability. It could also help agriculture create a smaller environmental imprint and improve U.S. food security.

Project leader Charles Sanchez of the University of Arizona (UA) says, “The successful implementation of this project will provide positive economic impacts for growers, reduced environmental impacts on water quality in the region, and enhance food security by using a finite and geopolitical resource (P) more efficiently.”

Phosphorus (P) is a key macro nutrient required in crop production, along with nitrogen and potassium.

The UA project is funded by a $147,000 grant from the Fertilizer Research and Education Program. FREP is financed through fertilizer purchases and administered by the California Department of Food and Agriculture.

Get the  latest agricultural news each day to your Inbox. Click here for the free Western Farm Press Daily e-mail newsletter.

Sanchez, a soil scientist, is based at the Maricopa Agricultural Center (MAC) in Maricopa, along with fellow project researchers Pedro Andrade, a precision agriculture specialist; and research specialist John Heun.

The research team also includes Kurt Nolte, Yuma County Cooperative Extension director based in Yuma.

The field research will be conducted in low desert vegetable production areas, including California’s Coachella Valley in a broccoli field; and in California’s Imperial Valley and Arizona’s Yuma County in iceberg lettuce fields.

About 90 percent of the nation’s winter supply of vegetables is grown in this mild winter weather region.

Each year, most winter vegetable fields require up to 550 pounds of monoammonium phosphate (MAP) which includes about 20 percent P. The fertilizer is knifed into the soil at preplant. The same amount of P is usually applied across the field whether specific areas need this amount or not.

“This project is about joining science and precision agriculture technology teaming up to determine which field areas need more or less phosphorus, and then applying only the needed amounts,” Sanchez says.

The project will utilize GPS-enabled soil electrical conductivity sensors to determine actual needs, and then create prescription maps to precisely apply the mineral.