Conservation tillage systems and their adoption in the United States
Conservation benefits of conservation tillage had been developed long before the production disadvantages were removed. Even though, in some cases, there are still production disadvantages and lower yields, compared to conventional tillage, conservation tillage is attractive to farmers primarily because of the potential for reduced production costs; conservation benefits are of secondary interest in most cases even though they accrue from the use of conservation tillage. This farmer interest in cost reduction will most certainly guide research inputs. Surveys of farmers have shown that more emphasis must be placed on all of the technology needed for a production system. In order to avoid financially-disastrous consequences, associated risk assessments are even required during the adoption period, i.e., the period when conservation tillage is replacing the conventional tillage. When a conservation-tillage-planting system is defined rigorously, based on the requirement that at least 30% of the surface should be covered with crop residue, the adoption averages about 25% of the cropland in the United States. Nine tillage management regions (TMR) in the United States were delineated based on climate, adapted crops and cropping systems. Adoption of conservation-tillage-planting systems ranged widely from 22 to 45% of the cropland in a TMR. Full-width systems such as mulch till, in which the whole field is tilled, were used much more than partial-width systems such as no-till, ridge till and strip till in which only strips are tilled. Adoption of these forms of conservation tillage are sensitive to the dominant-cropping systems in a TMR. Variations in adoption were often well related to the problems and benefits discussed by research on tillage-planting systems in the TMR.