Long‐Term Tillage on Yield and Water Use of Grain Sorghum and Winter Wheat

Core Ideas Average sorghum yield advantage was 120% for no tillage over conventional tillage and 55% for reduced tillage over conventional tillage. Average wheat yield advantage was 31% for no tillage over conventional tillage and 12% for reduced tillage over conventional tillage. Available soil water at planting in soil profile was less for conventional tillage than both no tillage and reduced tillage for both crops. There was a decline in wheat yield over time due to increased seasonal temperature. Tillage is among crop management factors that affect yield, profitability, and environmental quality. The objective of our study was to evaluate the effect of three long‐term tillage intensities; conventional tillage (CT), reduced tillage (RT), and no‐till (NT), on winter wheat (Triticum aestivum L.) and grain sorghum (Sorghum bicolor L.) yield, available soil water (ASW), and water productivity. The study was conducted near Tribune, KS, from 1991 through 2015 in a wheat–sorghum–fallow (WSF) rotation. The CT plots were tilled (primarily with a sweep plow), on average, four to five times per fallow season; NT plots used herbicides for weed control during fallow. The RT plots used a combination of herbicides and tillage for weed control during fallow prior to both crops for years 1991 to 2000; and, for the years 2001 to 2015, the RT system was NT before sorghum planting (short‐term NT) and CT before wheat planting. On average, there was a 31% wheat yield advantage for NT over CT, 16% NT over RT, and 12% RT over CT. On average, there was a 120% sorghum yield advantage for NT over CT, 41% NT over RT, and 55% RT over CT. Sorghum yields were 80% greater for continuous NT compared with short‐term NT (2001–2015 RT). The average of profile ASW at planting was less for CT compared with NT and RT. There was a significant yield and water productivity benefit in the order NT > RT > CT for both crops, but greater for sorghum than wheat.