A study was initiated in west-central Kansas near Tribune in 1991 to evaluate the long-term effects of tillage intensity on soil water and grain yield in a wheat-sorghum-fallow rotation grown on a silt loam soil. This is a semi-arid region with about 440 mm annual precipitation. The tillage systems were no-till (NT), reduced tillage (RT), and conventional tillage (CT). The CT system used a sweep plow for weed control during fallow while the NT system relied solely on herbicides. The RT system used a combination of tillage and herbicides for weed control. Reducing tillage intensity increased soil water at planting. Average profile soil water (240 cm profile) at wheat and sorghum planting was about 4 cm greater with RT and NT than with CT. Grain yields of wheat and grain sorghum increased with decreased tillage intensity. Average wheat yields were 2.0, 2.3, and 2.5 Mg ha-1 for CT, RT, and NT, respectively. Yield increases with reductions in tillage were greater with sorghum than wheat. Average sorghum yields were 2.3, 3.6, and 4.4 Mg ha-1 for CT, RT, and NT, respectively. For both crops, the yield benefit from reductions in tillage increased with time demonstrating the necessity of long-term studies to determine the effects of tillage systems.
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