CLIMATIC FACTORS CONTRIBUTING TO YEAR-TO-YEAR VARIATION IN GRAIN YIELD OF CORN ON BROOKSTON CLAY

Abstract

As much as 80% of the total among-year variance of grain yield in corn (Zea mays L.) in a 13-yr rotation experiment on Brookston clay soil could be accounted for by four climatic vectors: moisture deficit days, available moisture, corn heat units, and an effect allowing for the special weight of these during the critical tasselling-silking period. The nature of the response of corn yield to these climatic vectors depends on the level of N supplied via fertilizer, soil condition and fertility as maintained by rotation. Prediction of yield using weather data and water budget (to estimate moisture deficit days) for the soil type appears feasible where corn is fertilized, and can be done by 15 Aug., 6 wk before corn is mature. The need for basing area predictions on soil type and farm management practices is discussed.