Response of Soybeans (Glycine max) to Planting in Untilled, Weedy Seedbed on Clay Soil

Soybeans [Glycine max(L.) Merr.] were planted in an untilled, stale seedbed and conventionally tilled seedbed of Sharkey clay (Vertic Haplaquept) at Stoneville, Mississippi, in 1979 and 1980 to determine the feasibility of the stale -seedbed approach for soybean production in the Mississippi River Delta. Chemical weed control included applications of preplant, preemergence, and postemergence herbicides. Prickly sida (Sida spinosaL.) was the dominant weed in all tillage and weed-control systems. Perennial species were observed at harvest mostly in the stale - seedbed plots. Preemergence herbicides reduced the total weight of weeds per plot. Conventional seedbed preparation caused delays in planting of 3 weeks or more. In the presence of adequate soil moisture, yields of ‘Bedford,’ ‘Tracy’, and ‘Bragg’ cultivars from the stale - seedbed planting and areas that had been treated preemergence were always equal to or greater than yields from the tilled - seedbed plantings and areas that had been treated postemergence. In 1980, the hot, dry conditions of the growing season apparently negated any effect from either earlier planting or preemergence vs. post-emergence weed control.