Tillage intensity effects on corn and grain sorghum growth and productivity on a vertisol

Sustainable production systems and conservation tillage practices are needed to control water erosion on vertisols. Five levels of tillage intensity were tested for 3 yr for effects on growth and yield of corn (Zea mays L.) and grain sorghum [Sorghum bicolor (L.) Moench.] on a Houston Black clay soil (fine montmorillonitic, thermic Udic Pellusterts). Tillage intensity treatments included: chisel plow with secondary tillage; disk only; no-till with residue rakes at planting; no-till with midseason cultivation; and no-till. Corn plant populations were greater in tilled treatments than in no-till treatments in 2 of the 3 yr. Corn above-ground biomass production was generally reduced in no-till treatments early in the growing season, but by silking differences among treatments were not significantly different. Corn yielded 840 lb/acre more on average with tillage than with no-till. Plant population differences accounted for much of the difference in corn grain yields, with low plant populations restricting yield in some years. Grain sorghum populations were not consistently affected by tillage intensity, and biomass production was less sensitive to tillage intensity than corn. Grain sorghum yields were as large or larger in no-till treatments than in tilled treatments, except in one instance where population was reduced.