No-Till Corn Response to Crop Rotation and In-Row Residue Placement

Enhanced corn (Zea mays L.) yield responses to rotation in notill systems may be due to the types and amounts of surface-placed plant residue. Research in 1989, 1990, and 1995 evaluated no-till corn yield response to various preceding crops and examined whether inrow residue removal affected no-till corn response to rotation crops. The soil was an imperfectly drained loam (medium, mixed, weakly to moderately calcareous Typic Hapludalf). The preceding crops were: corn harvested for grain or whole-plant silage; hard red spring wheat (Triticum aestivum L.); barley (Hordeum vulgate L.); red clover (Trifolium pratense L.) cover crops, following barley, thai were killed by spraying either 3 wk (early-kill) or 1 d (late-kill) prior to corn planting; canola (Brassica napus L.); and soybean [Glycine max (L.) Merr.]. In-row residue was either retained while planting or cleared using planter-mounted, notched-disk row cleaners. Cleating in-row cover crop residue increased early-season corn growth and was associated with yield increases of 0.61 Mg ha⁻¹ (8%) following early-killed red clover and 0.43 Mg ha⁻¹ (6%) (P = 0.10) following late-killed red clover. In 2 of 3 yr, corn yields following early-killed red clover were similar to following soybean and greater than following grain corn, provided that in-row residue was cleared. Following the other crops, grain yield response to clearing in-row residue was smaller and less consistent over years. Preceding cropping affected early-season corn growth, with the largest plants at 5 wk after planting following either soybean or silage corn and the smallest following either red clover or grain corn. In 2 of 3 yr, when preceding crop effects on grain yield were statistically significant, yields following either soybean or spring wheat were more than 1.05 Mg ha⁻¹ (16%) higher than after grain corn. That yield increase occurred regardless of in-row residue placement. Removing corn stover by harvesting as silage increased corn yield by 0.86 Mg ha⁻¹ (12%) over yield following grain corn. During 1995, corn yield following silage corn was less than after soybean, canola, barley, or wheat; thus, no-fill corn yield response to rotation is not exclusively due to the presence of surface-placed stover. In-row residue placement and preceding cropping practices affected in-row soil temperature, but this could not totally account for the treatment effects on early-season corn growth and yields. Research supported by Agriculture and Agri-Food Canada, and the Ontario Ministry of Agriculture, Food and Rural Affairs.