Economic analysis of irrigation and deep tillage in soybean production systems on clay soil

Abstract

A 5-year study (1987–1991) was conducted on a Tunica clay (clayey over loamy, montmorillonitic, non-acid, thermic Vertic Haplaquept) to determine effects of irrigation and deep tillage on soybean yields and economic returns. Irrigation increased average yield of the conventional check treatment (disked) by 57% (3020 vs. 1924 kg ha −1). Under irrigation, yields from all deep-tilled treatments and the conventional check treatment were similar and averaged 3066 kg ha −1. Under non-irrigated conditions, yields from all deep-tilled treatments were similar, averaged 2829 kg ha −1, and were higher than the conventional check treatment that averaged 1924 kg ha −1. Average yields from the non-irrigated deep-tilled treatments were 92% as high as yields from comparable treatments with irrigation. Irrigation increased the average net returns of the conventional check treatment 75% ($206 vs. $118 ha −1. Over the 5-year study, average net returns to all irrigated treatments were similar and ranged from $194 to $206 ha −1. Net returns to the non-irrigated deep-tilled treatments averaged 156% higher than returns from the non-irrigated conventional check treatment ($302 vs. $118 ha −1) and was attributed to the higher yields of the deep-tilled treatments (2829 vs. 1924 kg ha −1). Net returns to the non-irrigated deep-tilled treatments also averaged 47% higher than returns from the irrigated conventional check treatment ($302 vs. $206 ha −1). This difference was attributed to the similarity of yields (2829 vs. 3020 kg ha −1) and the sizeable difference in specified costs of production ($335 vs. $481 ha −1) that favored non-irrigated production of soybean with deep-tillage.