Summerfallow oilseed barrier strips for wind erosion control: Influences on the subsequent crop

Abstract

Three-row flax (Linum usitattssimum L.) and mustard (Brassica juncea L.) barrier strips were seeded 10.7 m apart on conventional-tillage summerfallow in mid- to late July for wind erosion control at Swift Current to determine their effects on soil water, soil fertility, weeds, and yield of the subsequent wheat (Triticum aestivum L.) crop. In 3 yr with average winter precipitation, snow trapped by the strips replenished soil water consumed by the oilseeds. Over the relatively dry winter of 1991-1992, snow accumulation did not fully replenish water withdrawn by mustard barriers. The barrier strips did not affect soil water or subsequent spring wheat yields midway between the barriers. Wheat yields immediately on the previous oilseed strips averaged 6 and 17% less for flax and mustard, respectively. This yield depression was attributed to nitrogen deficiency. However, over the entire field, estimated wheat yield loss from using oilseed barriers was less than 2%. N and P fertilizer, applied when seeding the oilseed strips, increased subsequent wheat yields. Weeds were not numerous in the study and so trifluralin, applied when seeding the strips, had little effect on weeds and no effect on subsequent wheat yields. Although it caused slightly greater yield loss in the succeeding wheat crop, mustard has several advantages for summerfallow oilseed barrier strips compared with flax including a wider potential strip spacing, lower seeding rate, possible tolerance to grasshoppers, and potential for seeding later in the summerfallow period.