Cover crops are gaining in popularity among farmers seeking higher yields and fewer inputs, The Fertilizer Institute said last week.
The Fertilizer Institute, an industry group and creator of the 4R program – application of nutrients at the right source, right rate, right time and right place – says there are soil erosion, nitrogen production and weed suppression benefits from cover crops, among other benefits.
Eileen Kladivko, an agronomist and cover crops specialist with Purdue University, said with improved plant genetics, synthetic fertilizers, pesticides and machinery helping to increase yields, soil degradation is sometimes masked.
"Cover crops become an important part in helping to improve underlying soil resources and in obtaining the full potential benefits from additional crop inputs," she said.
According to Kladivko, cover crops are often planted for benefits, but not harvested. Some, however, may be suitable for grazing or haying. In general, she says the benefits of cover crops can fall into several categories:
• Scavenge or, "trap" nitrogen and protect water quality – the crops trap residual soil nitrate to prevent it from leaching into groundwater.
• Produce nitrogen – legumes fix atmospheric nitrogen for their own use. Once terminated, much of the nitrogen is released to succeeding crops as residues decompose.
• Prevent erosion – the crops cover the soil surface to protect against water and wind erosion.
• Build soil quality and/or recycle nutrients – cover crops improve soil's physical properties, increase soil's organic matter and increase soil's biological activity.
• Suppress weeds – some crops can suppress weeds by competition, shading or allelopathy.
• Enhance wildlife habitat – cover crops can provide water, cover and food for wildlife and increase landscape diversity.
These benefits will vary from year to year, depending on weather and the amount of growth of the cover crop, she says.
"After a drought year, it's even more important to plant a cover crop in the fall," Kladivko adds. Once the rains return, the cover crop will be there to scavenge some of those nutrients not used by the cash crop."
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Some farmers, like Chris VonHolten, a 4R Advocate who farms 1,080 acres of corn and soybeans near Walnut, Ill., chose a cover crop mix of radishes and oats on two locations to help absorb excess nutrients and prevent soil erosion.
Radishes and oats do not require a burndown because both crops winterkill.
"Some cover crops do not overwinter, so farmers generally don't need to plan for termination in the spring," Kladivko says. "Oats and oilseed radish are two common examples. On other crops, herbicide applied according to label directions, tillage, mowing or roller-crimping are effective termination methods."
"Good stewardship practices that include cover crops will help ensure we continue to achieve excellent yields over the long term," she added.
For more information on cover crops, Kladivko recommends checking with Extension agents, crop advisers and the Midwest Cover Crops Council. Also check out more information about cover crops and the 4R Nutrient Stewardship program online.
Source: The Fertilizer Institute