Water Use and Yield of Dryland Row Crops as Affected by Tillage
The dryland winter wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]-fallow rotation is suitable for large areas of the U.S. Great Plains. High temperatures and potential evapotranspiration limit the number of other crops that can be grown. Sunflower (Helianthus annuus L.) is drought tolerant, but crops such as corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] are perceived to lack sufficient heat and drought tolerance for semiarid areas. A study was conducted near Garden City, KS, from 1991 through 1995 to compare yield and water uses of conventional tillage (CT) and no tillage (NT) corn, grain sorghum, sunflower, and soybean to determine if crops other than grain sorghum are suitable for dryland production. Conventional tillage (CT) and no tillage (NT) were included in a wheat-row crop-fallow rotation. Corn and soybean were similar in their depletion of soil water, as were sorghum and sunflower. Below a depth of 1.2 m, sorghum and sunflower removed the most water. Sunflower removed the most water from the last 0.3 m of the profile and probably removed deeper water. Sorghum and sunflower removed an average of 19 mm more water from the 1.8-m soil profile than did corn and soybean. No-till increased yields of corn in 3 yr, of sorghum and sunflower in 2 yr, and of soybean in 1 yr. Corn had the greatest yield response to NT, averaging 31%. Average yields of corn were 25% higher than sorghum yields, whereas average yields of sunflower were 83% higher than soybean yields. Other crops can be successfully grown in the wheat-row crop-fallow rotation, but sorghum should occupy the most acres until the other crops have been tested under different climatic conditions.
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