The use of cover crops is one of many practices being used across Iowa to reduce nutrients in water. Iowa’s water quality improvement strategy, the Iowa Nutrient Reduction Strategy (NRS), outlines several agricultural practices that can be effective, recognizing the variability that exists in the weather, geographical landscape, and soil types.
Cover crops are an important component of Iowa NRS because of significant and immediate benefits across many landscapes. Planted in the late summer or fall, cover crops help reduce the loss of nitrogen and phosphorous from the soil and capture nutrients for next year’s crop. Cover crops are flexible, improve our soil resource over time and require a relatively low capital investment.
The benefits? For crop farmers, the use of cover crops such as winter rye can reduce nitrogen loss by 31 percent and phosphorus loss by 29 percent on average. Other important benefits include reduced soil erosion, improved weed control, and improved soil health. With long-term use, most farmers observe soil health changes such as improved water infiltration, increased soil organic matter, increased water retention capacity, and improved resilience to more dramatic seasonal climate events.
Livestock producers incorporating cover crops benefit from reduced feed costs from this additional source of forage.
Are you ready? Last year, Iowa farmers planted an estimated 760,000 acres of cover crops across the state. One scenario of the Iowa NRS calls for an effort to increase this to 12 – 17 million acres statewide to have a significant, positive impact on water quality.
Many factors determine how effective cover crops will be at reducing nutrient loss. Improvement of water quality from cover crops depends on growth and establishment. To get the full benefits of cover crops, consideration should be given to the short growing season between crop harvest and cold winter weather, inconsistent rainfall, and the potential for decreased seed-to-soil contact if using aerial seeding applications. Cost also is a consideration since the expense is offset by benefits such as improved soil fertility and yields that may take three or more years to accrue. Other benefits may not be so easily monetized by row crop producers such as reduced soil erosion and nutrient loss.
Planning a cover crop program up to a year in advance of seeding is more likely to bring success. This planning includes identification of goals for the cover, such as reducing soil erosion, scavenging nutrients, providing livestock forage, or reducing compaction. Individual producer goals will impact cover crop species seed selection, seeding methods and many other management aspects. It is helpful during the planning phase to consult with farmers, agronomists, and others with cover cropping experience. The plan should also consider priority fields, cover crop species and variety, seeding method and timing, herbicide program, crop rotation, termination approach, and integration with manure application. Although having a good plan is essential, flexibility in adapting the plan to current conditions also is important.
