DAVIS and WASHINGTON (March 28, 2019) – More than 80 percent of the world’s almonds are produced in California and this industry contributes $21 billion to the state’s economy. In recognition of the need to develop more resilient almond orchards, the Foundation for Food & Agriculture Research (FFAR) awarded a $225,000 Seeding Solutions Grant to the University of California, Davis, to improve soil health in almond orchards. The FFAR grant has been matched with funding from the Almond Board of California and almond growers for a total $450,000 investment.
Currently, almond growers clean the orchard floor so that no weeds, manures or organic matter are left before harvest begins. Almond harvesters then shake the trees to encourage the almond fruit to fall to the ground, where it dries out before growers transfer the fruit in its hull and shell to processing facilities. Since the almonds touch the ground during harvest, growers are not able to use manures, composts or other materials added to the soil that would contaminate the nuts.
The current practice deprives the soil of vital nutrients and creates additional costs for growers. Hulls and shells contain nitrogen and potassium, which the trees need to thrive. Clearing away the hulls and shells means growers must fertilize more. The hulls and shells are also 70 percent of the total almond weight, adding to transportation costs.
However, if the almond hulls and shells are left on the ground, they would improve the soil and save money.
“Healthy soils hold nutrients better, hold water better, improve crop disease resilience, capture carbon and reduce nitrogen leaching,” said Patrick H. Brown, professor in the Department of Plant Sciences at UC Davis. “This whole system change that eliminates almond contact with the orchard floor has the potential to reduce herbicide, fertilizer and pesticide use.”
UC Davis’s research will test advanced almond harvesting practices that increase soil fertility while ensuring food safety. The research team will catch almond fruits with machinery before they fall to the ground, removing their hulls in the field and recycling them on the orchard floor instead of discarding them in processing facilities. Eliminating the on-the-ground portion of the harvest will improve the ability of growers to use compost, manure and other materials designed to improve soil health.