This study compared conventional, reduced tillage and no-till systems for cotton, maize, soyabean and sorghum in the Mississippi Delta. Most of the necessary parameters (e.g. yields, costs, equipment, field operations) were obtained from published budgets. The conventional systems typically involved subsoiling, discing, field cultivation, hipping and in-season cultivation. The reduced tillage systems substituted herbicides for heavy pre-plant soil preparation and in-season cultivation, while no-till systems substituted herbicides for all tillage operations. A whole-farm, mixed integer programming model was developed to determine the most profitable crop/tillage combinations at different acreage sizes, assess the actual economies of size (in dollars per acre) in row crop farming, determine the number of acres required to maximize economic viability, determine the best acreage size to minimize or optimize full-time labour, and evaluate profitability trade-offs, including farm programme eligibility, under different tillage systems.
