Cover crops are key to combatting heavy spring rains

When it comes to soil conservation, a common headache for Iowa farmers is the spring deluge that causes fields to erode showing visible scouring and gullies. The amount of rain is only part of the problem - the timing is also a big issue, soon after planting when the soil and crops are most susceptible.

Just covering the soil with last year's crop residue provides some erosion defense, but when farmers try to fight off the all-too-common five-inch rain blast, it hasn't proven to be completely effective. Adding popular conservation practices like terraces and grassed waterways help further reduce erosion, but these earthen structures can also fail when rains come too hard and fast.

Residue management and erosion control practices are important pieces of the puzzle that protect the soil surface. However, the soil also needs more stability beneath the surface, says Barb Stewart, state agronomist with USDA's Natural Resources Conservation Service. 'Planting deep-rooted cover crops, such as cereal rye, annual ryegrass, winter wheat, and triticale help hold the soil in place,” she said. 'Keeping living roots in the ground really helps reduce erosion impacts during heavy rains.”

Steve Berger, a farmer in Washington County, has no-tilled for decades, but saw a noticeable difference in erosion control on hillsides once he started using cover crops. 'The last five or six years I've noticed much less erosion following heavy rains,” said Berger. 'The root system in the cereal rye really holds the soil in place.”

He says erosion control is just a short-term benefit of cover crops. 'Long-term, planting cover crops annually has gotten my soils back in shape with much more biological activity,” said Berger. 'I compare using no-till and cover crops to going to the gym. Once you start stirring the soil with tillage, it's like eating cake and ice cream - it just immediately takes away all of the hard work to get the soil in shape.”

Many farmers use a single cover crop species, but if other cover crop seeds are available and affordable, Iowa NRCS has developed multispecies cover crop mixes to help Iowa farmers achieve their individual goals. For erosion control, NRCS recommends a mix of winter hardy cover crops with those that establish quickly.

'The early establishers like oats, rape and mustard, will provide quick growth in the fall, but will winter kill,” said Stewart. 'The winter hardy cover crops, such as cereal rye and hairy vetch, spend much of the fall developing roots to survive winter. Both provide diversity in the plant and microbial community.”

Iowa NRCS also recommends cover crop mixes for fighting soil compaction, livestock grazing, nitrogen fixing, and building soil health. 'We can help determine what mix is best for you through the conservation planning process,” said Kurt Simon, state conservationist for NRCS in Iowa.

Simon recommends Iowa farmers develop a comprehensive conservation plan to help them make the best resource protection decisions for their farms. The planning process combines existing production methods with recommended conservation practices to best manage a farm's unique natural resources. It also allows farmers to improve sustainability and productivity.

Stewart says using a suite of conservation measures, such as residue management with no-till or strip-till, traditional erosion control practices like contour farming, buffer strips, terraces and grassed waterways to slow water flow, along with cover crops to hold the soil in place, will provide the best overall erosion protection during heavy storms.

NRCS provides financial assistance for cover crops and many other practices through the Environmental Quality Incentives Program (EQIP) and the Conservation Stewardship Program (CSP).

For more information about conservation planning and programs to benefit the natural resources on your farm, visit your local NRCS office or go to www.ia.nrcs.usda.gov.