Biofuel co-products as livestock feed - Opportunities and challenges

490Biofuel co-products as livestock feed – Opportunities and challengesFIGURE 7Relative intensity of United States maize farming fertilizer use from 1970 to 2010110%Fertilizer Use Per Bushel of Corn (relative to 1970)100%90%80%70%60%50%40%NitrogenK 2OP 2O 530%1970 1975 1980 1985 1990 1995 2000 2005 2010Source: Wang et al., 2011900800700FIGURE 8Energy consumption in United States maize farming, 1991 to 2005 (MJ per tonne)MJ/MT of Corn60050040030020010001991 1996 2001 2005Diesel Gasoline LPGElectricity NG TotalSources: Shapouri, Duffield and Graboski, 1995; Shapouri, Duffield and Wang, 2002; Shapouri, and McAloon, 2004; Shapouri et al., 2008.Analysis using these updated ratios shows that DDGSand WDGS could displace 27.9 million tonne of maize,which is 20 percent of the maize projected to be requiredfor ethanol production in 2015 according to the UnitedStates Environmental Protection Agency (EPA) renewablefuel standard. With a maize yield of 14 797 litres per hectareby 2015 in the United States, the DDGS and WDGS productionlevels equate to maize yields from 2.6 million hectare ofmaize fields. DGS could also displace significant amounts ofsoybean. The reduced demand for both maize and soybeancould produce LUC credits in computable general equilibrium(CGE) modelling for maize ethanol production.Land-use changeSince early 2008, several studies using economic modelssimulated direct and indirect LUC associated with the productionof maize ethanol and other biofuels in the UnitedStates. At first, these economic models did not addressseveral key issues, including crop yield increases in responseto increased commodity price, future grain supply and