Cover Crops Offer Financial and Environmental Benefits
Cover crops are plants planted on cropland in the off-season to help protect the soil from erosion. In addition, they improve soil and water quality, and in some cases, provide grazing for livestock. They can provide weed control, reducing the need for chemical inputs, and improve wildlife habitat.
Cover crops are becoming more common in the United States. In states like Iowa, where use has been encouraged as part of the state’s nutrient management plan, cover crop use increased from less than 10,000 acres in 2009 to 600,000 acres in 2016. State and federal government cost-share programs help promote the effort.
Typical cover crops vary by geography and purpose, and include small cereal grains such as cereal rye, legumes, radishes, turnips, and some annual grasses like sorghum or Sudan grass.
Utilizing cover crops requires planning and timing and often specialized equipment. Here you will find some of the ins and outs and special considerations for adopting the use of cover crops on your farm.
Cover Crop Benefits Are Many and Varied
Along with erosion control, one of the greatest benefits of growing cover crops is improved soil health. Variety of vegetation year-round increases organic matter and carbon in the soil, fixing nitrogen in the soil and reducing the need for applied nitrogen. Grazing cover crops gives an added benefit from manure.
Perennial grasses can help reduce the salinity, or salt content, of soil. Excess salt hoards water, keeping it from plants and it can take many years of perennial grass growth to reclaim saline soils.
Cover crops can help with weed control by reducing weed density and size. The cover takes its share of water, light, and nutrients, limiting weed size and reducing the amount of needed herbicide. Identifying the species of weed to control, and the timing of emergence and growth, are key elements of a weed control program, as is planting a cover that will produce adequate biomass.
Consider the Goal When Choosing a Cover Crop
Each cover crop has its specialty and it is important to choose the right one for the required job. Cereal rye, or winter rye varieties planted in cooler climates, helps break up hard soil and inhibits small weeds from developing. The tillage radish, or daikon radish, has a deep taproot that reaches nutrients otherwise lost to leaching. Hairy vetch is excellent for fixing nitrogen. Red clover as a clover cover crop is a nitrogen scavenger that makes for good grazing and insect habitat. Cover crop mixes work in concert to perform a variety of tasks.
Pairing a cover crop with the cash crop that shares its field is important for getting the most benefit from the effort. Rye, for example, pairs well with soybeans. Rye suppresses weeds, provides erosion control during heavy spring rains, and its fibrous roots help prevent soil compaction from equipment during spring planting.
Considerations for Planting Cover Crops
There are multiple ways to plant cover crops, and timing is key to getting a good stand. Seeding options have advanced beyond drilling to include use of high-clearance air seeders, aerial seeding, and interseeding between the rows of a standing crop.
Special planter attachments also enable farmers to plant traditional crops into standing cover crops. The cover crop can help provide weed and moisture control as the cash crop gets its start.
While this approach may work well for soybeans, there can be disease considerations for corn as some grass borne pathogens can be passed from one crop to the other.
Methods for Killing Cover Crops
Success with cover crops involves killing the crop in the right way at the right time. The following cash crop depends on it, and Mother Nature doesn’t always cooperate, so planning is essential. If using herbicide, be sure to use the right product for both the cover and cash crop, and abide by temperature and precipitation restrictions. Some cover crops will winterkill, but many crops and many parts of the country cannot depend on that strategy. Whatever method is used, termination should occur two to three weeks before planting corn in early spring, and within a few days of planting soybeans.
How Much Do Cover Crops Cost?
Farm economists continue to study the profitability. Based on examples provided by farmers, the short-term results are often dependent on cost-share programs to make them pay, while those planting cover crops for several years claim the effort pays off in increased soil quality. There are online worksheets available to help farmers assess the costs, and the experts agree it is important for each producer to run his or her own numbers rather than depending on another’s example.
Cost analysis show cover crops produce the most financial benefit when part of a livestock grazing program. When factoring in hay, fuel, and labor costs, turning cows on to green cover through much of the winter saves some producers upwards of $150 per cow, with the added benefit of improved nutrition and soil health.
Cover Crop Mistakes to Avoid
There can be a learning curve, leading producers new to the practice to be afraid of making mistakes. The experts say the best way to overcome the uncertainty is to learn from the steps and missteps of the early adopters. Have firm goals, research the techniques, and take the dive. Then be patient. Soil quality and crop yields won’t improve overnight. Cover crops are a long-term prospect.
In addition to the more generally known benefits, some farmers are finding harvesting the small grains for seed can add value to their cropping systems.
Cover crops can also provide habitat for pollinators, increasing bee populations in stressed regions.