Corn stover is composed of stems, leaves, and cobs resulting from the corn har­vest. This lignocellulosic material is considered as one of the most promising feedstocks for ethanol production in the United States since it is the most abun­dant agricultural residue in that country. For instance, the corn was the second most cultivated crop in the United States in 2005 (29.8 million ha) after soybeans (29.9 million ha) and followed by wheat (20.2 million ha) and cotton (5.3 million ha; FAO, 2007a). However, in terms of product harvested, corn widely outpaces the soybean (299.9 million ton of corn versus 85.0 million ton of soybeans). In addition, the generation of residues in the case of soybeans is modest com­pared to corn. Corn stover availabilities have been estimated at 153 million for per year (dry basis) in the United States relative to other agricultural residues (about 58 million ton) and demonstrates the huge volumes generated (Kadam and McMillan, 2003).

A factor to be considered in the case of agricultural residues is that, unlike cane bagasse, their total utilization can lead to soil erosion and reduction of its organic matter content. For this, the sustainable fraction of residues to be collected should be defined. This fraction depends on the climate conditions, crop rotation, soil fertility, land scope, and employed agronomic practices. For example, it is estimated that it is necessary to cover the soil surface after har­vesting with more than 30% of harvest residues to avoid the erosion due to water runoff. For this reason and to evaluate the availability of feedstocks for ethanol production, higher percentages are used to consider the uncertainty generated by different local conditions (Kim and Dale, 2004). Taking into account this factor, the amount of corn stover that can be collected in a sustainable way in the United States has been estimated at 80 to 100 million ton (dry basis) per year. Only a small portion of this amount (about 20 million ton) has the potential to be used for purposes other than ethanol production, such as, for instance, the production of agglomerates, pulp, or furfural. In this way, the production of 11 million L of fuel ethanol will imply the utilization of only 40% of collectable corn stover (Kadam and McMillan, 2003). The global potential for ethanol production from this material reaches 72.45 million L. Undoubtedly, the implementation of a pro­gram for fuel ethanol production from corn stover would reduce the pressure over corn prices.