Profit, yield, and soil quality effects of tillage systems in corn-soybean rotations

Adoption of conservation tillage for corn (Zea mays L.) and soybean (Glycine max L.) rotations, has stagnated over the past several years despite the evidence of the benefits to erosion control, soil health, and associated natural resources derived from conservation tillage. The Monsanto Centers of Excellence were established to evaluate the potential benefits of conservation tillage across a range of soils and climates. Our objective is to summarize the results from field-scale studies conducted at 13 Monsanto Centers of Excellence sites in nine states from 1998 through 2002. Strip-tillage, no-tillage, and conventional corn production, and narrow- and wide-row, no-tillage and conventional tillage soybean production were evaluated in this study. Nine of the 13 sites included a stale seedbed "fast start" corn treatment by which the seedbed is prepared in the fall by conventional tillage and a spring herbicide burndown if needed. Neither soil bulk density nor crop emergence showed any significant differences among tillage systems for either crop throughout the five-year study. Earthworm populations were higher with no-tillage than conventional tillage. Soil quality indicators were not significantly different among the tillage systems. Soil temperature at the 5 cm depth was similar for stripand conventional-tillage, with both being higher than no-tillage Yield differences among tillage systems within years were not significant for either crop, but profit for no-tillage and strip-tillage corn was the highest in four of five years. The five-year average profit for soybean was also highest for the no-tillage, narrow-row system. Rotating corn and soybean using no-tillage systems resulted in $130 to $145 ha-1 ($53 to $59 ac-1) more profit than the other practices. Farmers, crop consultants, and others should carefully consider overall profit rather than just crop yield when evaluating alternative tillage practices.