If you are beginning or finishing up harvest already for your cash crops, it's not too late to plant cover crops, says Sarah Carlson. By incorporating more "green" plants into the "brown" months, you can help keep soils covered through the winter and during vulnerable times of the year. Cover crops are an important tool farmers may use to retain nitrogen and soil on their farm fields.
Carlson is research director for Practical Farmers of Iowa and has worked with a number of farmers the past several years using various cover crops and trying out related management practices. She offers the following observations and suggestions, along with her Top 10 Tips For Cover Crop Management. Contact her at 515-232-5661 or firstname.lastname@example.org if you have questions.
In natural ecosystems, most of the time the ground is not frozen and there are plants growing, recycling water and nutrients, and fixing carbon, or at the least they are covering the soil. Research indicates multiple benefits from the use of cover crops in annual cropping systems.
• Plants and plant litter protect soil from erosion by intercepting raindrops, slowing surface water flow, increasing infiltration, and holding soil with roots.
• Plants moderate soil and air temperatures by intercepting radiation, shading or mulching the soil surface, and transpiring water.
• Lastly, plants maintain soil productivity by preventing soil nutrient loss, increasing soil carbon, improving water holding capacity, and maintaining soil structure.
The Midwest agricultural landscapes which are dominated by corn and soybeans, however, typically only have plants growing for four to six months of the year and often are tilled between harvest and planting. This period without living plants leaves the soil, nutrients and water exposed and unprotected for up to eight months.
Why is it a good idea for farmers to plant cover crops?
Putting more "green" plants into the "brown" months will help protect soil and water quality and maintain natural cycles for water, carbon, nutrients and soil organisms now and in the future. This can be accomplished by growing winter cover crops in the months between harvest and planting of corn and soybean.
Even with these benefits to the soil and water, many farmers are hesitant to add cover crops to their farming system but with good management, this practice can successfully be added to farms in Iowa.
Top 10 management tips for cover crops
1) Overseed cover crops at or before soybean leaf yellowing or black layer of corn.
2) The planting rates for overseeding are 50% greater than the drilling planting rate.
3) Coincide overseeding with rainfall or adequate soil moisture conditions.
4) If fall harvest is early follow the combine with the cover crop planter.
5) Winter rye/cereal rye is the most commonly used cover crop in Iowa.
6) Don't confuse winter rye/cereal rye with ryegrass.
7) A good alternative to planting winter rye as a cover crop—if corn is to be planted in the field the next spring--is to plant oats in the fall as a cover because they winterkill.
8) Hairy vetch, a legume, can be seeded with winter rye to increase nitrogen to the following crop.
9) Cover crops can decrease the amount of stored feeds needed for cattle when grazed in the spring.
10) Don't forget, cover crops need management. Check spring growth early to avoid too much growth.