Including a small grain, such as winter wheat or barley, in rotation with soybean has both economic and environmental benefits. Beginning in 2012, Ohio State University established field trials at the Western Agricultural Research Station in Clark County, Ohio, and the Northwest Agricultural Research Station in Wood County, Ohio, to compare a corn-soybean rotation to a corn-soybean-wheat rotation. Here are the top five reasons for including a small grain into rotation with corn and soybean:
1. Increase in soybean yield. In field research, an average increase of 3 bushels per acre in soybean yield was recorded when winter wheat was included in the rotation. Research from other universities show a similar “rotation effect,” with higher levels of crop diversity resulting in greater yield of corn and soybean. The rotation effect is more pronounced in years with nonideal growing conditions (e.g., drought or flood).
2. Improvement in soybean stand. In 2018, at the Western Agricultural Research Station, a field trial received heavy rainfall after planting. In plots without wheat included in the rotation, the average soybean stand was 89,000 plants per acre. However, when wheat was included in the rotation, the average soybean stand was 109,000 plants per acre. This may have been due to better water infiltration and less ponding in plots that had wheat included in the rotation.
3. Improvements in soil health. After seven years (two winter wheat crops), soil organic matter was 0.4% greater at the Northwest Agricultural Station and 0.7% greater at the Western Agricultural Research Station when wheat was included in rotation. These trials were established in 2012 and have been maintained without tillage or winter wheat straw removal, which contributed to the increase in soil organic matter. Fall-planted small-grain crops provide soil health benefits that protect water quality, including reduced erosion by acting as a cover crop.
4. Decrease soybean cyst nematode. It’s estimated that approximately 80% of soybean fields in Ohio have detectable levels of soybean cyst nematode. Including a nonhost crop, such as winter wheat or barley, in rotation will help reduce the SCN population.
5. Decrease in disease pressure. Some diseases, such as frogeye leaf spot, overwinter on crop residue. Crop rotation is a tool that can help alleviate disease pressure by breaking up plant disease cycles.
Planting of small grains can usually occur after soybean harvest in the fall and can be accomplished using a grain drill, in many cases. Small-grain harvest can occur in late June or early July (depending on your location and the small grain chosen), and it may be possible to double-crop beans in the rotation.
Planting small grains in the rotation can also allow for field maintenance activities that may not occur each year, such as a lime application for soil pH adjustment or the planting of a cover crop. So, when making long-range plans for your operation be sure to consider whether a small grain crop has a fit in your rotation.
Laura Lindsey and Alex Lindsey are both certified crop advisers, and Alex Lindsey is also a certified professional agronomist. Both are assistant professors in the OSU Department of Horticulture and Crop Science.