Management options for drought-stressed soybeans
Soybeans can tolerate short periods of heat and drought at this time by aborting flowers and forming more later. But the crop will not bloom indefinitely and under prolonged heat and drought may be unable to recover. Although stress during flowering can reduce the length of the flowering period, bean plants can continue to flower for several weeks if no pods are set. Determinate soybean varieties will normally bloom for 3 to 4 weeks or so under excellent conditions, and indeterminate varieties will bloom for 4 to 6 weeks. These periods of bloom can be shortened under extremely stressful conditions.
If no pods are set after the normal blooming period, it is possible that the crop will not set many pods or make much seed yield. If fields have very few pods set at all by the time they have reached the end of their blooming period, the crop should be hayed.
Because of extremely high July temperatures, irrigated fields are not immune to the effects of drought stress. With numerous days over 100 degrees F, even irrigated plants can have reduced pod set or pod fill.
With soybean prices as high as they are, the decision to hay becomes more difficult. K-State Agricultural Economics crop production budgets estimate soybean production costs including land charges at about $200 to more than $325 per acre. At $15.85/bushel (the local new crop price listed for Manhattan on July 19, 2012), that takes only 13 to 21 bushels per acre to break even. Potential returns from a small grain crop must be balanced with local demand or markets for forage, which is strong in most areas.