Increasing available soil water for a crop can be accomplished with both deep tillage and irrigation. Both have the potential to replace or complement the other due to their common function. The addition of a crop rotation may also enhance or diminish the response from irrigation and/or deep tillage. The major objective of this study was to determine long-term effects of different levels of furrow irrigation and in-row subsoil tillage on lint yield and economic returns for cotton grown on alluvial silty clay loam soils in a cotton/corn cropping sequence. A secondary objective was to determine the ability and efficiency of deep tillage and irrigation to replace and/or complement each other in the cropping system. Field experiments were conducted at Tribbett, MS on silty clay loam soils from 1999 through 2004. In-row subsoil tillage was performed with a low-till parabolic subsoiler. A roll-out pipe system was used to furrow water the irrigated plots. Production costs were calculated and include direct costs plus total specified costs excluding land rent, general farm overhead, and returns to management. Growing non-irrigated cotton without deep tillage in this cotton/corn sequence on these silty clay loam soils that were prone to backwater flooding gave the highest average net returns. It appears producers should neither subsoil, nor furrow irrigate and the two should never be combined, based on this study. These results emphasize the need for drainage and support the need for further research on these type soils in the absence of drainage problems.
