Cover crop use in agriculture is nothing new. Cover crops used as "green manure" date back more than 2,300 years. Prior to World War II, many experiment stations did extensive work on cover crops and crop rotations. In the 1930s, a term often used for cover crops was "soil-improving crops." These crops included clovers, alfalfa, Sudan grass, rye, oats, vetch and even weeds.
After World War II (entering the Green Revolution era), there was an abundant, cheap source of commercially produced nitrogen fertilizer, and production agriculture began to shift away from extensive cover crop use. Now the pendulum has swung back, and there is renewed interest in cover crops for their soil-improving qualities, abilities to reduce wind and water erosion, and other benefits.
An issue we face is that a lot of cover crop knowledge obtained through previous, early research work must be relearned. That is where the Noble Research Institute's applied cover crop research plays a role.
One of the major livestock production systems in the Southern Great Plains is grazing young, weaned beef cattle (stockers) on small grain, mostly wheat, from fall to spring. The land used to grow small grain pasture is typically summer-fallowed in an attempt to conserve moisture for the next small grain crop. Fallowing ground during the summer leaves it vulnerable to wind and water erosion. Also, the high summer temperatures can elevate soil temperatures, which can reduce soil microbial activity.
In our research, we want to know how we can enhance this system by growing a summer cover crop to protect and improve the soil without affecting winter pasture production, animal performance and economics.
To do this, we took an existing winter pasture study area and established a summer cover crop/winter pasture grazing study where the main factors are tillage (no-till and till) and cover crop (summer cover crop and summer fallow). The summer cover crop is a multispecies mixture of 50 percent grass (millet and corn) and 50 percent broadleaves (cowpeas, soybeans, sunn hemp and buckwheat).
Our evaluation measures forage production, animal performance, water infiltration, soil microbial activity, soil bulk density, soil moisture, nutrient cycling, and system economics of both cover crops and winter pasture. Stocker cattle graze both the cover crop and winter pasture.
Several small plot studies are also in place to evaluate other aspects of summer cover crops and winter pasture production. These include evaluating the effects of cover crop termination date, cover crop seeding rate, and terminating or not terminating cover crops on winter pasture production.
This research is producing needed scientific information on summer cover crop impacts on winter pasture livestock grazing systems, which will help producers.