Desiccation of Grain Sorghum by Foliar Application of Nitrogen Solution
1977
Donnelly, K. J. | Vanderlip, R. L. | Murphy, L. S.
Adverse weather delaying harvest is a frequent problem of grain sorghum [Sorghum bicolor (L.) Moench] producers. This study evaluated the effects of foliar application of 32% nitrogen urea-ammonium nitrate solution (UAN) to desiccate grain sorghum before harvest. Nitrogen solutions were applied at O, 67, and 134 kg N/ha when grain had reached physiological maturity. Two hybrids (‘RS671’ and ‘E57’) and two planting dates were compared at two locations in 1972 and 1973. Grain samples were collected weekly until harvest for moisture determination, then grain and forage yields and N contents were determined. The effects of N carryover to succeeding grain sorghum crops were also evaluated. Grain drying was accelerated significantly only when N was applied at or before physiological maturity. However, application before physiological maturity reduced grain yields. Rainfall and high humidity resulting in poor drying conditions more than offset desiccation effects after grain moisture reached 20 to 25%. Leaf loss reduced harvestable forage yields, as expected. Desiccant N gave little or no Increase in N content of the grain or forage. Soil N and grain sorghum yields were increased slightly the next year in some plots, but no significant carryover of desiccant N was found in others. Low recovery of applied N in the treated crop at harvest and low carryover to the succeeding crop suggests that volatilization losses following treatment were high.
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