Let’s cultivate our soils wisely

A low-flow water emitter sits on the dry, cracked soil of an almond orchard near Stockton in March.
A low-flow water emitter sits on the dry, cracked soil of an almond orchard near Stockton in March. Associated Press file

California’s severe drought has focused attention on the critical role that soils have in agriculture and the economy of the Central Valley.

Farmers are investigating a range of practices to get more out of every drop of water, including reduced tillage and preserving residue to limit evaporation. These practices also increase the storage of rain and irrigation water by reducing runoff and boosting groundwater recharge. In dry and wet times, soils that function well for crop production and water storage are critical.

This year is the International Year of Soils, designated by the United Nations to recognize the critical importance of soils in food security, the ecosystem, human health and the sustained life of our planet. Awareness has also been raised nationally by the U.S. Department of Agriculture and in California through the Healthy Soils Initiative that Gov. Jerry Brown submitted to the Legislature. The Soil Science Society of America and the International Union of Soil Sciences have also led the charge.

These initiatives rely on the principles and practices of good soil management – minimum tillage, cover crops and biological diversity that give soils the ability to adapt to a wide array of conditions.

Researchers and farmers from California and around the world validate the important role that minimum tillage practices have in capturing and storing more rainfall. Research in the San Joaquin Valley has confirmed what is widely shown in other dry areas of the world – combining minimum tillage with cover crops can reduce evaporation from the soil by as much as 16 percent, or about 4 inches of water during the summer.

A network of soil evaluations is now being created across California through the efforts of farmers and partners including the University of California Cooperative Extension, local Resource Conservation Districts and the USDA Natural Resources Conservation Service. This grass-roots effort aims to share information on successful and innovative soil management approaches.

Dwayne Beck, a researcher at the Dakota Lakes Research Farm in Pierre, S.D., said, “The challenges we face in designing production and soil management paradigms must be envisioned over truly the long haul. Not five or 10 years into the future, but 100 or more years out. These challenges are nothing short of the agronomic and ecological equivalent of the space race of the early 1960s.”

Reaching the moon was not achieved by modest ambitions, but by setting bold goals that demanded creative and long-term dedication and innovation. We owe nothing less to our soils.

Jeff Mitchell is an instructor at the University of California, Davis, and researcher in the San Joaquin Valley. Randy Southard is chairman of the Land, Air and Water Resources Department at UC Davis.