Soybeans are an acceptable cover crop. Soybeans from seed sources that are not treated with insecticide or fungicide seed treatments can be used as a forage crop. Treated seed sources may have limitations due to label restriction or the label does not have feed use approval. CFAES faculty are currently working with seed treatment manufactures to develop a seed treatment products list and whether soybeans which were treated with those products can be used as a forage.
Soybean is an acceptable cover crop as it is agronomically sound for the area for erosion control or other purposes related to conservation or soil improvement.
To optimize the use of soybean as a cover crop, consider the following:
- Planting dates. USDA NRCS cover crop practice guidelines state that soybean should be planted between June 15 and August 15 in northern Ohio and June 1 and August 30 in southern Ohio.
- Plant in narrow rows. The USDA NRCS cover crop practice guidelines do not specify a row width for a soybean cover crop, but planting in less than 30-inch rows will maximize ground cover and improve weed suppression. DO NOT BROADCAST TREATED SEED. We want to minimize the risk of seed treatment exposure to non-target organisms.
- Seeding rate. USDA NRCS cover crop guidelines indicate that soybean should be seeded at 54 lb/acre if to be planted as a pure stand (100% soybean) cover crop. At a seed size of 2,800 seeds/lb, this would be a seeding rate of ~151,000 seeds/acre. Higher rates may be used; however, seed treatment labels may limit the amount of active ingredient per acre which can impact upper seeding rate limits.
- Check your license agreement and talk with your seed dealer. Most trait licenses have a clause stating that the crop can be used for “one commercial crop.” You will want to verify with your seed dealer that the cover crop represents a commercial crop prior to planting.
Forage use:
Soybeans planted at this time of year and harvested as silage will yield about 2 tons of dry matter per acre (dry plants to 65 to 70% moisture before chopping). Narrow rows will yield about 15% more than wide rows. Harvest between R5 and R7 stage, but no later than R7 (one pod on the stem is a mature color).
Silage harvest will be easier than dry hay because of difficulty in getting the crop dry. Silage harvesting later creates issues with the high oil content of the beans, and more leaf shatter will inhibit a good fermentation. Harvesting later than R5 to R7 creates an issue with the high oil content of the beans, and more leaf shatter will inhibit a good fermentation. Feed quality would be similar to early bloom alfalfa.
Check seed treatment labels or ask seed suppliers for any restrictions on using soybean seed for forage, as some seed treatments may not allow it. Review any herbicides applied and see labels for restrictions before use to verify that the crop can still be used for animal feed.
Adding an annual grass such as oats, spring triticale, or sudangrass could be a good option to lower the protein content for some classes of livestock and improve the mechanical handling of this crop.
Reference:
https://agcrops.osu.edu/newsletter/corn-newsletter/2019-21/considerations-using-soybeans-cover-crop
Updated: 7/9/2019