Predicting Corn Grain Yield Using Silage Starch Content and Crop Adjuster Methods
2014
Lauer, J. G. | Roth, G. W. | Zarnstorff, M.
Multi-peril crop insurance (MPCI) requires that if corn (Zea mays L.) is insured for grain and the producer wants to use it for another purpose, that is, silage, the producer must have the corn grain yield appraised before corn silage harvest. This appraisal requires an adjuster to determine the weight of grain corn, and based on stage of maturity, apply a factor to convert the determined weight to the weight of mature corn at 155 g kg–¹ moisture. This study was designed to test the hypothesis that corn grain yield can be estimated accurately before grain is combine harvested using the USDA–Risk Management Agency (RMA) methods and routine silage quality measurements for starch. Corn was established at two locations from 2006 to 2008. Management factors involving planting date, hybrid, and harvest timing were applied to create a range in yield and forage quality. Both RMA methods and the starch-based method underestimated combine grain yield by 4 to 36% at silage harvest stages between 75 and 25% kernel milk (KM). At silage harvest, the starch method estimated final combine grain yield more accurately than the RMA maturity line weight (MLW) method, but when applied after silage harvest or just before grain harvest, the RMA Weight method was the better predictor of final combine grain yield. With careful assessment, starch-analysis of silage theoretically could produce an equitable estimate of grain yield for insurance adjustments.
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