Soybean Growth and Soil Microbial Populations under Conventional and Conservational Tillage Systems

Abstract

Tillage systems play an important role in crop growth and soil improvement. This study was conducted to determine the best tillage system for the dark-soil area of northeast China with darkclay soil type (Millisol) and to examine the influence of different tillage systems on soybean [Glycine max (L.) Merr.] growth and soil microbial populations. Three conventional tillage systems and two conservational tillage systems were tested. Plant height and biomass as reflected by dry shoot and dry root weight under the no-till system were significantly reduced as compared with other tillage systems. The bacterial, fungal, and actinomycete populations reached their highest levels at soybean R2 (blooming) stage. The disease severity of root rot and population dynamics of bacteria, fungi, and actinomycetes in conservational tillage appeared to be higher than those in conventional systems; the latter were associated with an increased populations of Fusarium spp. and Trichoderma spp. Based on these research findings, a conventional tillage with reduced plowing frequency and intensity and increased crop-residue coverage would be a reasonable recommendation for soybean production in the dark-soil area of northeast China.