Minimum tillage systems have been promoted for their soil conservation benefits, however, profitability is a major factor governing the adoption of soil conserving practices. Under conditions of similar crop productivity and input (i.e., fertilizer and pesticide) use, tillage costs become the key determinant of profitability. Two studies were conducted to assess tillage costs within regions of eastern Canada. In the first study, fuel consumption and tractor drawbar energy for specific tillage implements and minimum tillage were determined on a sandy loam Podzolic soil in Prince Edward Island. The second study, tillage cost scenarios on a farm scale (360 ha) were evaluated for different minimum tillage systems, applicable to Atlantic Canada, within a three-year potato (Solanum tuberosum L.)-barley (Hordeum vulgare L.)-forage rotation, and a barley-soybean (Glycine mar L. Merr.) rotation. An instrumented tractor fitted with transducers indicated that fuel usage for seedbed preparation and crop establishment was lower with several minimum tillage practices (10.0-23.7 l ha(-1)), than conventional mouldboard ploughing (27.6 l ha(-1)). Tractor drawbar energy was also greater under the conventional mouldboard ploughed system (140.4 MJ ha(-1)), in comparison with minimum tillage (53.3-127.3 MJ ha(-1)). For the tillage cost scenarios in both rotations, the calculated cost differences were based on estimated changes in both capital costs of tillage equipment and overall operating costs. Conventional mouldboard ploughing combined with secondary tillage was the most costly tillage system in both rotations. Replacement of the mouldboard plough with various combinations of alternative tillage systems (e.g., chisel plough, disc harrow, power harrow) provided annual tillage cost savings of 44-60% for the three-year potato rotation, and 10-40% for the barley-soybean rotation. Based on the assumption that tillage is the only variable input cost (i.e., absence of yield penalties or differences in other input cost variables), the adoption of various minimum tillage practices would be more economical than the conventional mouldboard ploughing system. (C) 1998 Elsevier Science B.V. All rights reserved.
