Evaluation of Long Term No-till Effects on Soil Fertility

The adoption of no-till seeding systems in western Canada has been driven by a variety of factors, with moisture conservation and economic efficiency the major ones. The conversion of fields to no-till has been shown to increase soil organic carbon (C) and nitrogen (N) as well as water use efficiency by crops. Together, these factorslead to increased productive potential of the soil. This project was initiated on two adjacent fields, one recently converted to no-till and the other with a 20-year no-till history, to determine the differences in N and phosphorus (P) nutrient supply and fertilizer response.

Under the drier than normal conditions recorded in 2003, grain yields at the experimental site were very low. Using the same plots and fertilizer treatments, a P response was not recorded in field pea in 2004, regardless of the previous wheat crop history. For spring wheat in 2004, there was no effect of P additions on the long-term no-till site, but there was an effect on the short-term no-till site where yields were increased with the addition of up to 20 lb P₂O₅/A. These results support past work indicating a lack of response for field pea to P fertilizer additions. They also show that residual P in the long-term no-till site met the wheat P requirements, while the absence of this nutrient supply resulted in a positive response on the short-term site. This project will be continued in 2005. SK-36F