Biofuels in Perspective

18 Biofuels
Figure 2.5 Researchers at the University of Illinois at Urbana-Champaign are studying production and
harvesting of the perennial grass Miscanthus as a dedicated energy crop.
Source: John Caveny, photo courtesy of the University of Illinois.
An environmental and economic ‘optimum’ removal balances sufficient retention of
residues to avoid erosion losses and maintain soil quality while using excess residue as
biomass feedstock. The impact of varying levels of stover and straw removal will depend on
local conditions and practices. Farmer involvement in the development of residue collection
plans will be critical.
2.5 Erosion Control
Past studies of removal effects are helpful, especially for erosion control, but are often
incomplete when addressing field removal of crop residues. 11 This is due partly to the
wide variation in local conditions and system complexity – it is not an easy task – and
partly to skepticism of the need for these studies. Several early attempts at removing
biomass for industrial uses failed, and many potential participants remain concerned about
soil tilth.
Excess availability of crop residue is dependent on the amount that must remain as soil
cover to limit wind and water erosion. Erosion is a function of climate, soil properties,
topography and cropping and support practices like contour planting and minimum tillage.