Cover crops offer more than just soil health

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Farm Forum

One of the main reasons producers are growing cover crops is soil health. It is well documented that cover crops increases soil quality by preventing erosion, increasing soil infiltration, enhance soil biological activity, and eventually aid in improving soil organic matter. Another major contribution of cover crops can be supplemental forage. Grazing cover crops in fall and early spring will allow livestock producers to extend the grazing season and provide rest period for the pastures.

Biomass production

The amount of above ground dry matter or total biomass produced is critical in forage production. The USDA-NRCS from the study conducted in eastern South Dakota has reported that the biomass production from cover crop mixtures is very similar to rangeland or pasture situations. Generally, cool season cover crops mixes such pea, radish, turnip, oat, barley, etc. will produce less biomass than warm season grass species such as sorghum, millet, sudangrass, etc.

Because of abundant growing period, cover crops after small grains produce fairly good amount of dry matter for fall grazing, however, the same is not true in corn-soybean rotation. One of the methods that few growers have adopted is to fly in or broadcast seed cover crops before corn is fully canopied (growth stage V4 to V6) so that there will be some green plants for grazing livestock when put on the field following grain harvest. Another time to broadcast cover crops into corn would be when the plants start opening up the canopy in September (growth stage half milkline). For spring forage options, cereal rye or winter rye can also be drilled after corn harvest or flown in when corn is close to maturity. Due to its tremendous winter hardiness, winter rye over winters even when planted late and produces rapid growth in the spring. When two methods of seeding, i.e. broadcast vs drilled, the SDSU research reports have shown that broadcast seeded cover crops produce biomass of about 70% of the drilled cover crops.

Species selection

Selecting cover crop mixes with right species is vital for total forage production and quality. Warm season grasses produce more biomass but contains usually less crude protein whereas, the cool season legumes and brassicas are high in quality but do not produce as much biomass. Mixing cool season grass species like oat, barley, and wheat with legumes and brassicas such as peas, radish, lentils, will provide balance between production and quality for fall forages. Besides tonnage and quality, another factor that needs to be considered while selecting species is bloat. High water content in some common cover crop species such as brassicas can cause bloat in animals and reduce the total intake needed for optimum performance. Cover crop blends with good blends of both grass and brassicas (not more than 60% of the blend) can help alleviate this problem.

Note: A cover crop meeting hosted by SDSU Extension is on the horizon. An Cove Crop Forum event will be held in Huron on Dec. 6 from 9 a.m. to 3:30 p.m. at Crossroad Hotel and Huron Event Center. The registration can be done at the gate for $20 (cash or check). More information is available on igrow.org.