WATER-YIELD RELATIONS OF SEVERAL SPRING-PLANTED DRYLAND CROPS FOLLOWING WINTER-WHEAT

A winter wheat (Triticum aestivum L.)-fallow cropping system has devel oped in the central Great Plains as a means to stabilize crop producti on in a highly variable climate. As an alternative, a flexible croppin g system partially based on soil water at planting may allow producers to minimize risk while allowing some additional crop production durin g wetter climate cycles. Water-yield relations are critical in the dev elopment of flexible cropping systems. The experiment was conducted ne ar Sidney, NE, on a Keith silt loam (fine silty, mixed mesic Aridic Ar giustoll) to determine the response of five spring-planted crops (corn (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], pinto bea n (Phaseolus vulgaris L.), prose millet (Panicum miliaceum L.), and su nflower (Helianthus annuus L.)) to three different soil water levels t he year following winter wheat harvest. Water use of all crops increas ed with increasing soil water at planting. The grain yield of pinto be an and prose millet responded positively to soil water at planting. So il water at planting accounted for less than half of the total variabi lity in grain yield for corn, grain sorghum, and sunflower. Soil water at planting appears to be useful in determining the success of planti ng the two short duration crops (pinto bean and proso millet) the year after winter wheat harvest. For the long duration crops (corn, grain sorghum, and sunflower) other factors, such as precipitation near the time of flowering, may be more important in determining success.