Cropping systems for clay soil: crop rotation and irrigation effects on soybean and wheat doublecropping.
1991
Wesley R.A. | Heatherly L.G. | Elmore C.D.
Doublecropping soybean [Glycine max (L.) Merr.] and winter wheat (Triticum aestivum L.) is the most popular crop rotation in the USA. Field experiments were conducted from 1984 to 1989 to evaluate alternate cropping systems for a Tunica clay soil (clayey over loamy, montmorillonitic, nonacid, thermic Vertic Haplaquept) in the lower Mississippi River Valley. Specific objectives were to (i) determine the seed yield response of monocrop soybean and doublecrop soybean and wheat grown in rotation in irrigated and nonirrigated environments, and (ii) determine the increase in gross income for soybean due to irrigation. Seed yields of monocrop soybean averaged over the 6-yr test period exceeded yield from doublecrop soybean in the irrigated (41.3 vs. 32.5 bu/acre) and nonirrigated (18.0 vs. 9.2 bu/acre) environments, respectively. Yields of soybean from corn (Zea mays L.)/wheat-soybean and sorghum [Sorghum bicolor (L.) Moench.]/wheat-soybean rotations were similar in the irrigated and in the nonirrigated experiments. Average wheat yields from the wheat-soybean, corn/wheat-soybean, and sorghum/wheat-soybean systems indicated no great advantage for any system. Irrigation of soybean increased yields and gross income in all years except 1989. Gross income and returns per inch of irrigation water varied considerably across years, however, and were a function of commodity prices and the amount of irrigation water applied.
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