After considering the effects of genetic yield potential and the environment, planting date is one of the primary management practices under the farmer’s control that can highly influence soybean yields. In recent years, Kansas producers have been planting soybeans slightly earlier -- at the rate of about one third-of-day per year. The past growing seasons, however, the “50% planting date” mark was achieved at a similar time (first week of June) statewide.
Kansas planting dates and maturity groups
Soybeans can be planted over a wide range of dates (Figure 1, upper panel) with adequate soil moisture conditions, although germination and emergence could be reduced and/or delayed in cool soils (less than 60 degrees F). The recommended maturity varies across Kansas by area (Figure 1, lower panel).
Figure 1. Recommended soybean planting dates (upper panel) and suggested maturity groups (bottom panel) across Kansas. Maps from K-State Research and Extension.
- Ultimately, weather patterns dictate soybean yields, especially under dryland conditions. There is no guarantee that any certain planting date will always work out the best when it comes to soybean yields in Kansas. In fact, the distribution and amount of rainfall and the day/night temperature variations around flowering and during the grain filling periods have large impacts on defining soybean yield potential. Thus, when the risk of drought stress during the growing season is high, diversifying planting dates may be a good approach to consider.
- When planting early, seed should be treated with a fungicide and insecticide. Selecting varieties with resistance to soybean cyst nematode and sudden death syndrome is advisable. Do not plant into soils that are too wet. Also, do not plant until soil temperatures are close to 60 degrees F. If planted into soils cooler than 60 degrees F, seedlings may eventually emerge but will have poor vigor.
- In drier areas of Kansas and on shallow soils, yields have been most consistent when planting soybeans in late May to early June. By planting during that window, soybeans will bloom and fill seed in August and early September, when nights are cooler and the worst of heat and drought stress is usually over.
Ignacio Ciampitti, Crop Production and Cropping Systems Specialist