Effect of seedbed preparation on soil aggregation, surface moisture and crop production.

In a three-year study at four soil sites in western Canada, data indicated that erodible aggregates increased in the surface 2.5 cm of undisturbed soil as initial tillage was delayed for periods of one to three weeks after the soil could first be worked. Changes in erodible material due to initial tillage were minimal, and in fact showed a decrease at site 2. After secondary tillage and seeding, all locations showed an increase in erodible material. Only one site showed a difference in erodible material due to the type of machine used. Moisture losses were slightly less when the oneway disc harrow was used at two locations, and no difference at the other two. Tillage treatment did not result in yield differences on an individual site basis; however, a combined analysis of yield data showed a small difference due to tillage machine used. Although there were differences in soil aggregates, moisture loss and crop yield, they were relatively small, inconsistent between years and location, and, therefore, shou...