November 20, 2018
While many growers are experiencing record yields in the Midwest because of timely summer rain, some areas experienced drought (Figure 1). After a drought, farmers should take inventory of how the drought impacted their operation. Challenges in the field following a drought may include herbicide carryover, weed pressure, nutrient carryover and soil health impacts.
Figure 1. U.S. Drought Monitor Map showing areas that experienced varying levels of drought. Map courtesy of NDMC-UNL.1
The potential for herbicide carryover into the next year can increase after a drought. In dry conditions with limited rainfall, the rate of herbicide degradation can be slow enough to allow for potential carryover into the next season. Many factors contribute to carryover potential. Typically, higher pH is a concern for herbicides such as the sulfonylurea (SU’s) or triazines. After last year’s dry winter and spring, crop responses from atrazine and fomesafen products were noticed. Growers should also be wary of HPPD and imidazoline chemistries. Ample rainfall or snow this winter and spring can help reduce the concern for herbicide carryover into next year’s crop.
Weed pressure can often rise from the lack of crop canopy during a drought. Additionally, growers occasionally cut spending on herbicide applications leaving more seed available to germinate in the field. Without control, these weed seeds can germinate with early spring moisture and impact yield potential negatively. Best management practices for successful weed control are to rely on residual herbicides and spray when weeds are less than 4 inches tall.
Drought promotes nutrients like nitrogen, phosphorus and sulfur to persist at higher levels in soils than in years with adequate rainfall. These nutrients can help the following crop if they stay in the root zone through the winter and spring. Growers should pull soil samples to avoid overapplication of fertilizer but also not underapply and limit yield potential.
After a drought year, growers must turn their focus to farming for success. Next year will be different altogether. The heat and rain will hit at different times. Farmers should utilize their crop rotation and crop residue to build up the profile moisture and soil health.
Sources:
1Blunden, J. 2018. U.S. Drought Monitor. The National Drought Mitigation Center. University of Nebraska-Lincoln. The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC-UNL. https://droughtmonitor.unl.edu/
Post-Drought Agronomic Challenges: Herbicide Carryover, Weed Management, Soil Fertility. Corn + Soybean Digest. February 2013.
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