Cover crops can enhance soil fertility and improve yields
Cover crops are crops that are grown in dormant season to help promote healthy soil and ideally, increase crop yield. Cover crops are a “multipurpose farm tool.”
Cover crops can help accomplish several goals, including: reducing soil erosion and runoff, keeping fertilizer in the soil and out of the water supply, increasing organic matter, aiding in weed management and several other benefits. One of the many questions among agriculturalists is, can cover crops help increase production?
According to the University of Arkansas Research and Extension, cover crops are not grown for harvest, but rather to protect and improve soils. They are commonly referred to as “green manure” because at the end of their growing cycle, cover crops should be terminated and tilled back into the soil, where nutrients are released as the plants decay.
“Cover crops have the potential to be the backbone of any sustainable agriculture producer,” Kyle Richner, Marshfield, Mo., MFA Bulk Plant manager said. “Cover crops can help hold the nutrients in the soil. Plus, you can also use cover crops as a mulch for the next planting season. This will help increase microbial activity and reduce weed competition.”
One of the many important aspects of cover crops is the root system. The roots grow much deeper into the soil than commodity crops. Typical Ozarks commodity crops include corn, soybeans and wheat. The root depth of these crops is much shallower than that of cover crops. The addition of cover crops allows untapped nutrients with greater soil depth to be utilized, specifically carbon.
Many of the benefits of cover crops are a direct result of what occurs in crop production that neither the producer or consumer can physically see. The biodiversity of cover crops has a direct impact on increasing microbial activity (bacteria, fungi and nematodes) in the soil and occurs more rapidly when organic carbon is added through leguminous cover crops. Microbes are responsible for nitrogen fixation, the process of converting nitrous gas in the environment into a usable form for plants.
Through instating practices that focus on maximizing soil health, a grower can see an increase in yield of commodity crops. But is the increase enough to offset the cost obtained through planting the cover crop? Studies show yes, over time, a grower will see additional profits from planting cover crops. Researchers used legume and non-legume cover crops on wheat-corn-soybean and corn-soybean rotation on claypan soils. They compared input cost and yield to analyze benefits. The study lasted four years and the first two years were marketed by drought and poor growing conditions. The third year, fields showed an average of 8 percent increase in crop yield, which resulted in a 30 percent increase in revenue per acre. On the flip side, the initial input cost was a 37 percent increase per acre, resulting in no increased profits. Moving on to the fourth year of the study, 2015, revenues and yields increased and researchers reduced input cost.
As research continues, it is evident that more nutrient loss occurs when fields are bare after harvest, especially in areas with heavy rainfall. Cover crops benefits the soil during fallow periods by adding nutrients and reducing soil erosion.
“Use of cover crops is important in the Ozarks, where row crop farming lacks diversity,” said Dhruba Dhakal, University of Missouri Extension agronomist. “The lack of diversity reduces soil productivity and increases pest and disease pressure. It also increases weed pressure.”
Cover crops are typically associated with conservation programs, targeted at improving the quality and health of soil. But research by the Noble Research Institute suggest that one benefit offered by planting a cover crop, that is rarely acknowledged, is the use as a forage for grazing livestock.
According to the Noble Research Institute, cover crops can fill two predominate forage production gaps. The first is for a summer cover crop to be used for grazing in conjunction with wheat between harvesting and planting. The second is for a cool-season cover crop to be interseeded into a warm-season pasture, providing early spring season forage for cattle.
There are several resources available to help growers begin utilization of cover crops, including grant opportunities through the USDA Natural Resources Conservation Services (NRCS).
If you have questions or an interest in cover crops, reach out to the USDA, NRCS or local agronomist for direction.