Use of cover crops for forage supply
The use of cover crops has become a “hot” topic as producers look to increase forage supplies as well as benefiting soil health. Cover crops provide alternative benefits to the producer and the environment. A few of these benefits include improving soil quality by protecting soil from erosion, increasing soil microbial activity and cycling nutrients, decreasing excess of nitrogen or adding carbon to the soil. Some of the main concerns for adding cover crops for your forage production are: (1) When will I plant? (2) When and how to harvest? and (3) Which cover crops provide the best forage?
When and what to plant
Many cover crops can work for forage supply, but the selection of which cover crop to use will depend on when you want to plant it and what is the purpose. Usually cover crops are planted from July through middle of September after small grain or corn silage is harvested. A useful guide to cover crop mixes after small grains can be found at NRCS web site (http://1.usa.gov/VIMdQM).
Cover crops create new opportunities to enhance rotation diversity. Cover crops are often described in four broad categories: cool season grasses (barley and oats), cool season broadleaves (field peas and turnips), warm season grasses (millet and sorghum), and warm season broadleaves (cowpea and sunflower). Producers have successfully incorporated cover crops with silage corn for dairy production.
Incorporation of cover crops for forage supply
One way to incorporate cover crops into a grain or livestock production system is to seed winter rye after corn silage. This practice would benefit the soil by providing cover and also is an opportunity to produce another forage crop. The use of winter rye in a corn-soybean rotation could improve soil quality, reduce soil erosion, suppress winter annual weeds, and diversify forage production for hay or silage. In a study conducted by SDSU, winter rye was grown after various relative maturity corn was harvested for grain to observe rye biomass to be used as possible forage crop. The trials were conducted at Beresford and South Shore, SD. The rye biomass was determined in the spring before planting soybean. Overall, winter rye biomass at 15% moisture at Beresford was 3580 lbs/acre, whereas at South Shore, it was 1260 lbs/acre. The average crude protein (CP) was around 19%, whereas relative feed value (RFV) ranged from 118 (South Shore) to 144 (Beresford) between two locations. In these studies, differences among rye biomass grown after corn with differing maturity levels was minimal, which suggest that putting rye cover crops after regular maturity corn would maximize profits. The impact of the rye forage crop on soybean yields depended on summer rainfall. At Beresford in 2012, under extreme drought, soybean yields were severely decreased by the use of a rye forage crop, whereas in 2013 when rainfall was adequate, no negative impact on soybean yield was observed.
Cover crops planted after corn silage harvest provide supplemental option of grazing good quality forage in late fall or early winter. Major things to consider while planting cover crop (single or in mixes) are the seed price and the plant back restriction interval of chemical used in the preceding crops. Also, using cover crop that is different in growth habit than that of the following crop would help break pest pressure in the field.