Residue Management and Minimum Tillage Systems for Soybean following Wheat

Abstract

AbstractThe acceptance of no‐till systems for soybean [Glycine max (L.) Merr.] production following winter wheat (Triticum aestivum L.) on fine‐textured soils in Ontario has been hampered by soybean yield reductions due to unfavorable seedbed conditions. This research was conducted to identify alternative tillage and residue management systems that will enhance emergence, growth, and yield of soybean following winter wheat. Seven tillage and residue management systems, comprising fall moldboard plow, fall chisel plow, fall disk only, fall zone‐till, no‐till, no‐till (with wheat straw baled), and no‐till (with wheat straw and stubble removed), were evaluated following winter wheat on fine‐textured soils from 1994 to 1996 at six different sites near Centralia and Wyoming in southwestern Ontario. Spring soil moisture was lower in the fall tillage treatments than in no‐till with wheat residue, but moisture differences did not vary among fall tillage treatments. No‐till seedbeds had the highest soil moisture contents, the lowest proportion of fine soil aggregates (<5 mm in diameter), and the greatest penetrometer resistance. No‐till soybean growth was delayed and yields were reduced as the level of wheat residue left after planting increased. Soybean seed yield was negatively correlated with surface residue cover, but positively correlated with soil aggregates <5 mm in diameter at all sites. Fall zone‐till and fall disk systems generally improved in‐row seedbed conditions (higher fine soil aggregates and lower soil resistance), and increased seed yields by 5 to 29% relative to no‐till treatments. Fall zone‐till and fall tandem disk systems were the best conservation tillage alternatives to fall moldboard plowing.