Impact of Zero-tillage on Soil Quality Changes Under Crop Rotations and Fertilizer Treatments in a Black Soil

Assess whether or there has been a significant change in soil quality and/or yield trends in the 6 years since the field soil in this study were converted to no-tillage from conventional tillage.


12 Sep 2001


    There has been a marked trend to adopt reduced (direct seeding) tillage on the Canadian prairies during the past decade. Many producers have also been moving away from monoculture cereals to more diversified cropping systems and have also increased their use of fertilizers and included more legumes in rotations. In the late 1980's following 30 years of a crop rotation experiment on a heavy clay soil at Indian Head, we sampled soil from the various treatments and determined the effect of the aforementioned factors on various soil quality attributes (e.g., N supplying power, soil microbial biomass, soil respiration, soil aggregation, leaching of N & P, yield trends). We showed that is was beneficial both from an economic and environmental standpoint to reduce frequency of fallowing, to use fertilizers (N & P) responsibly (i.e., based on soil test), to include legumes in the crop rotation (although we showed the need to add P to such systems or yields would eventually suffer as available P diminished in soil). We were unable to demonstrate any negative effect of straw removal on soil quality except with regards to a decrease in soil aggregate stability; yields were unaffected. This information is urgently needed by prairie producers because we receive requests regularly from all 3 prairie provinces enquiring into this subject. Further, Dr. Campbell has been asked to be guest speaker at a Farmers meeting in Williston, ND in Feb. to speak on the effect of straw removal on soil quality.

    During the first 34 years of this experiment, conventional (mechanical) tillage was used to control weeds. However, in 1990 the study was changed to zero tillage. This is analogous to what many prairie farmers are now doing. There is very little information on how such a move to zero tillage would influence soil quality. For example, the ability of the soil to supply N & P to plants may be reduced as N & P is immobilized (and N is denitrified) and this might negatively affect yields and protein.

    This study presents an opportunity to determine if there has been a significant change in soil quality and/or yield trends in the 6 years since the study was converted to zero tillage. We have records of yields and N & P content of grain which will allow us to determine how these are trending with the change to zero tillage and to relate those changes in soil quality.