Since soil organic matter is extremely important for no-till success, it’s definitely to your benefit to leave all of your crop residue in the field. Not only does higher soil organic matter encourage a slow-release source of nutrients, but it will also improve the structure of your soils.
Results from research studies done in Alberta, Canada, by Agriculture & Agri-Food Canada, indicate that not only is there normally more crop residue with no-till, but that it is more valuable to the soil.
N.Z. Lupwayi of the Beaverlodge Research Farm in Alberta, Canada, says that crop residues do not immediately decompose completely with either zero-till or conventional tillage. He maintains that it’s the more resistant parts of the residue that decompose slowly that are turned into valuable soil organic matter. The “No-Till-Age”chart at left shows the results of this Canadian research on the amount of residue that was produced and added to the soil.
When the crops were harvested (measured at flowering time for the green manure clover crop), crop residues were weighed and analyzed for nitrogen. The amount of nitrogen from the residues was also measured periodically over a 1-year period while wheat was grown. With the exception of canola, each of the crops produced a larger amount of residue under zero-till conditions.
Even though greater amounts of pea residues than clover residues were added to the soil, Lupwayi says that more nitrogen was actually added with the clover rather than with the pea residues.