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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.

Diverse crop rotations sustain crop productivity by increasing crop water productivity and improving soil structure. Th e objective of this study was to compare two 4-yr winter wheat (Triticum aestivum L.) and grain sorghum (Sorghum bicolor L.) rotations in terms of grain yield, available soil water, and water productivity along with continuous winter wheat. A fi eld study was conducted from 1996 through 2015 on a deep silt loam soil near Tribune, KS. Th e study consisted of three crop rotations: continuous annual wheat (WW), wheat-wheat-sorghumfallow (WWSF), and wheat-sorghum-sorghum-fallow (WSSF). Grain yield, biomass, water productivity, and soil water were all greater for sorghum aft er wheat compared with sorghum aft er sorghum. Similarly, grain yield, biomass, water productivity, and soil water were all greater for wheat aft er fallow compared with wheat aft er wheat. Th e yield of the second wheat crop was 80% of the fi rst wheat crop in WWSF, whereas the yield of a second sorghum was only 63% of the fi rst sorghum crop in WSSF. Th e average crop water productivity (7 kg ha -1 mm -1 ) of the WSSF rotation was greater than the other rotations. On average, the WSSF system produced 2.05 Mg ha -1 yr -1 wheat equivalent yield (WEY), which was similar to the 1.96 Mg ha -1 yr -1 WEY from the WWSF rotation and greater than WW, which produced 1.53 Mg ha -1 yr -1 of wheat grain. A WSF rotation would have produced 2.0 Mg ha -1 yr -1 WEY, so the 4-yr rotations were not more productive than a 3-yr WSF rotation.

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