Abstract
Definitive responses to pre- and post-plant tillage are hard to locate in the literature. These tillage responses are usually confounded with other factors. A 2×2 factorial treatment design for pre- and post-plant tillage was implemented in a modified split plot experimental design. Main plots were preplant tillage and sub-plots were post-plant tillage. The experiment was conducted from 1992 through 1994 on a clayey soil at Keiser, AR; 1992 through 1993 on a silt loam at Marianna, AR; and in 1994 on a silt loam at Pine Tree, AR. Grain yield was determined. Soil samples were taken for soil moisture determinations at depths of 0–5 cm, 5–15 cm, 15–30 cm, and 30–45 cm. Crop budgets were generated using production practices and equipment commensurate with commercial farming operations in the area. Results showed that preplant tillage and no-till resulted in equivalent grain yields on clay soil. However, net returns on no-till were equal to or superior to preplant tillage on clay soils across all years. On silt loam soils, both preplant and post-plant tillage main effects were significant for both yield and net returns. Results varied with year on both clayey and silt loam soils. Breakeven analysis indicated that breakeven yield differences were relatively minor across tillage systems. Further, breakeven prices on the clayey soils were generally lower than on the silt loam soils reflecting changes in relative profitability across soil type. Soil water measurements clearly demonstrated the soil's function of water storage for ultimate release to the plant during droughty periods. This function was not affected by tillage system in this study.
Acknowledgments
The Arkansas Soybean Promotion Board is gratefully acknowledged for providing funds that made this study possible. We would also like to thank the following research assistants for assisting with this study Eddie Gordon, Ira Eldridge, Wayne Vance, George Palmer, and John Falkner.