Abstract
Agricultural residues such as corn (Zea mays L.) stover are a
potential feedstock for bioenergy and bio-based products that could
reduceU.S. dependence on foreign oil. Collection of such residues must
take into account concerns that residue removal could increase erosion,
reduce crop productivity, and deplete soil carbon and nutrients. This article
estimates where and how much corn stover can be collected sustainably
in the USA using existing commercial equipment and estimates
costs of that collection. Erosion constraints to collection were considered
explicitly, and crop productivity and soil nutrient constraints
were considered implicitly, by recognizing the value of residues for
maintaining soil moisture and including the cost of fertilizer to replace
nutrients removed. Possible soil carbon loss was not considered in the
analysis. With an annual production of 196 million Mg of corn grain
(about9.2 billion bushels), the USA produces 196 million Mg of stover.
Under current rotation and tillage practices, about 30% of this stover could
be collected for less than $33 per Mg, taking into consideration erosion
and soil moisture concerns and nutrient replacement costs. Wind erosion
is a major constraint to stover collection. Analysis suggests three
regions of the country (central Illinois, northern Iowa/southern Minnesota,
and along the Platte River in Nebraska) produce sufficient stover
to support large biorefineries with one million Mg per year feedstock
demands and that if farmers converted to universal no-till production of
corn, then over 100 million Mg of stover could be collected annually
without causing erosion to exceed the tolerable soil loss.