El Nino and Drought Could Deliver a One-Two Punch to Unprotected Soils

Taylor HillmanDrought, Environment, Soil, Water, Weather

Plowing and shaping fields in the fall is common practice in many parts of California, but the USDA’s Natural Resources Conservation Service is recommending a different strategy this year.

“Let your plow rest this fall,” recommends NRCS State Agronomist Dennis Chessman. “If we get high-intensity, above-normal rainfall like El Nino has brought in the past, fields will really benefit from any crop residue left on the surface from this season’s crop,” says Chessman. “Doing all tillage in the spring before you plant would be a better bet,” he says.

Any living or dead plant matter gives a “field shield” to otherwise vulnerable soil. The energy from each raindrop can be deflected by a living plant (cover crop) or even by dead residue, Chessman explains. Raindrops’ energy knock the soil particles free and erosion is set in motion. “Covered soil stays in place,” Chessman summarizes.

Soil moisture is another plus of leaving fields untilled this fall. Residue (as well as living plants) slows down rain and lets it infiltrate rather than running off the field. “This builds soil moisture which will come in very handy next spring,” says Chessman. “If you capture several inches of rainfall in the soil it can help you delay or eliminate an early season irrigation.”

Planting a cover

Right now—mid October to mid November—is also the ideal time to plant a cover crop, says Chessman. The cover cop, like the plant residue, protects the soil from erosion, but it can provide numerous additional benefits—depending on a farmer’s goals.

Species mixtures are good. Including a legume is a great way to add nitrogen to the soil. Other species can be chosen for pollinator benefits. Regular use of cover crops can add organic matter to the soil and boost its water holding capacity as well as its ability to cycle nutrients. NRCS planners can help growers select the best species mix for their crop and their purposes, says Chessman.

But even if it’s just a single species of small grain, something as simple as barley or rye, you will gain a measure of erosion control and moisture trapping advantages for this winter, Chessman emphasizes.

Residue and cover crops can keep soil on the field and keep rainfall in the soil, summarizes Chessman. “It will put us in a better place next spring,” he says.

For technical and possible financial assistance in planning cover crops, tillage plans and other conservation, visit your local NRCS office http://www.nrcs.usda.gov/wps/portal/nrcs/main/ca/contact/local/.