The authors found that, in general, moderate harvest
of the corn stover resulted in a slight increase in grain yield at 50% of
the sites. Average grain yields under no-till were significantly lower
than yields under conventional tillage when stover was left in the
field, but not when it was harvested. Though the report represents a
valuable contribution to the understanding of the effects of residue removal
the high variability of the data and the different treatments evaluated
at each site have so far precluded an in depth analysis of these
trends. Of the experimental sites established within this regional partnership,
only the sites in Illinois and Minnesota provide
information on factors that are likely to interact with residue removal,
such as tillage options, and fertilizer nitrogen (N) additions. Specifically
for Illinois, Coulter and Nafziger (2008) reported on the effect of three
residue removal rates (no removal, partial, full), tillage (chisel, no-till)
and four N rates (67 to 258 kg N ha−1) on corn yield under continuous
corn production across four sites and two consecutive years. In environments
with lower rainfall and lighter-textured soil, corn grain yield
responded negatively to residue removal and N fertilization only
under no-till, likely due to increased water retention that increased
the crop response to N. On heavier-textured soilswith abundant rainfall,
yields were similar between chisel plow and no-till with full residue removal,
yet yields were higher with tillage with no or partial removal of
residues