TRANSITION FROM CONVENTIONAL TO NO-TILLAGE IN POORLY DRAINED CLAY

No-tillage has been recognized as one of the best tillage practices in preventing soil from erosion and sequestering carbon. However, agricultural producers have seen negative results in clay soils (e.g. soil compaction and poor crop yield) immediately after converting conventional tillage to no-tillage. A three-year on-farm study was conducted to investigate two different transition strategies for switching from conventional tillage to no-tillage in poorly drained, heavy clay soils. Field plots were established in Manitoba, Canada in 2006, 2007, and 2008. The corresponding crops were canola, wheat, and barley. The transition strategies used were planting alfalfa ahead of time before no-tillage and performing subsoiling before no-tillage. Conventional tillage was also included as a control. Field measurements were performed on residue cover, soil properties (moisture content, bulk density, and cone index), and plant performance (plant biomass and grain yields). Results showed that no-tillage plots on alfalfa had over 90% residue cover, and the residue covers of subsoiling plots were higher than the conventionally-tilled plots. As compared with the conventional tillage, the no-tillage soil established on the alfalfa field had lower moisture content and higher cone index, which adversely affected the plant biomass and grain yields; whereas the no-tillage soil established after subsoiling had lower soil bulk density and cone index, which favored better plant biomass and grain yields.