Chemical Fallow in a Winter Wheat-Fallow Rotation

Abstract

Five fallow treatments in an alternate winter wheat ( Triticum aestivum L.) fallow rotation experiment were compared over a 6-yr period at North Platte, Nebraska. During the 14-month fallow period from winter wheat harvest until winter wheat planting, plots receiving no tillage (weeds were controlled by herbicides) had the least weed growth, most soil water stored, and highest amount of surface mulch maintained. Also, the plots receiving only herbicides had the highest grain yields of all treatments. However, an average of 3.8 herbicide applications were needed to control grass weeds missed by 2-chloro-4-(ethylamino)-6-(isopropylamino)- s -triazine (atrazine) during the last 5.5 months of the fallow period. Greatest weed growth during the fallow period was on plots that received only tillage and occurred during the first 3 months after harvest.