Planting soybeans in fields that were planted to soybeans the previous year is not generally recommended. The best-case scenario for producers who do so is a yield loss of about 5 percent compared to soybeans planted after corn. In many cases, however, the yield loss for soybeans after soybeans can reach 20 percent or more.
Disease, insects and plant stress can all lead to yield loss. Therefore, if a producer is going to plant soybeans after soybeans it is important that the benefits of doing so are likely to exceed the increased risk of high yield loss.
Short-term profitability is a driving force behind many farmers’ decision to plant soybeans in the same field for subsequent years, but it is important to factor in how this decision may impact long-term profitability. Data continues to show that crop rotation for soybeans is highly beneficial. If, after careful consideration, you have decided to plant soybeans after soybeans, it is important that you manage risk as much as possible. The following information will help you to do just that:
- Plant different varieties of soybeans. Planting the same variety of soybeans each year will expose the weaknesses within that variety. Planting significantly different varieties will help to shield against disease loss.
- Be aware of altered pest complexes. Planting soybeans after soybeans will alter the pest complexes in your fields and these alterations will likely take years to reverse. Cover crops are unable to remedy these alterations.
- Get ahead of disease problems. It is critical that you scout your fields thoroughly, so you stay on top of any potential disease issues and incorporate fungicides and insecticides. You will want to use a seed treatment at the max a.i. fungicide rate. You also will want to use a pre-emergence herbicide. Keep in mind that any weed escapes are likely to increase when planting soybeans after soybeans.
- Test for soybean cyst nematode (SCN). Always select a SCN-resistant variety as SCN flourishes in long-term soybean cropping systems.
- Consider seeding rates. If white mold was a problem, reduce the seeding rates of your fields.
- Take soil samples. When soybeans are rotated with well-fertilized corn, carryover fertilizers are often relied upon. When soybeans are not rotated in this manner additional fertilizer may be required, especially one with potassium.