Corn and Soybeans Losing the Battle with Drought

August 24, 2011

Corn and soybeans are losing the battle with drought. Severe soil moisture deficiencies have built up over the past 2 months with ongoing dryness. Even a 1-inch rain is not enough to stem the tide of deterioration, soaking readily into parched fields. Drought is always knocking on the door when field conditions are very dry.

Many crop areas of the Midwest have accrued a 4-6 inch moisture deficit in the past 60 days. That equates to less than half of normal moisture in the two months. Much of this period was hot, increasing transpiration, the water lost through pores in plant leaves, and thus worsening drought stress.

Complicating matters further, drought occurred during a period of high crop moisture requirements. Corn uses up .20-.25 inch per day in the pollination stage when kernels are set on the ear. Midwest corn pollinated in a July heat wave. Blank ear tips reveal unsuccessful pollination and a reduced yield. Kernels filling need generous rainfall and cooler weather to optimize the grain weight.

Soybean water requirements peak in the pod setting- and bean filling stage in August. Both the number of pods set on the plant and bean size have been adversely affected by drought. Pod setting was 83% complete August 22. It takes 30-40 days for beans to fill, once the pods are set. This is an ongoing process that occurs mainly in the month of August.

See the rainfall plots over time that confirm worsening drought. Selected cities are all key growing areas for corn and soybeaans. Yields are projected sharply lower, with the exception of Nebraska, where July-August rainfall was quite ample.