Continued conservation tillage produces a stratified
distribution of K in the soil profile. For the past three years
in Ontario, we compared methods of K placement in
combination with tillage strategies in long-term no-till
production fields. Generally, we found conservation-till
corn to respond more frequently to K in a starter band than
corn grown with moldboard plow tillage. Wherever
applied K has benefited corn, we have generally observed a
soybean response to the residual fertilizer as well. This
response has been less consistent in some years than in
others, but the residual benefit ranged from a 5 to 17
percent yield boost. This research has stimulated further
projects, funded by the Ontario Soybean Growers, to
evaluate placement effects of K on soybeans.