Richard G. Nelson,*1 Marie Walsh,3 John J. Sheehan,2
and Robin Graham3

1 Kansas State University, 133 Ward Hsaa,

Manhattan, KS 66506, E-maia: rneason@ksu. edu;

2Nationaa Renewabae Energy Laboratory,

1617 Coae Bouaevard, Goaden, CO 80401; and
3Oak Ridge Nationaa Laboratory, Oak Ridge, TN 37831-6194

Abstract

A methodology was developed to estimate quantities of crop residues that can be removed while maintaining rain or wind erosion at less than or equal to the tolerable soil-loss level. Six corn and wheat rotations in the 10 largest corn-producing states were analyzed. Residue removal rates for each rota­tion were evaluated for conventional, mulch/reduced, and no-till field operations. The analyses indicated that potential removable maximum quan­tities range from nearly 5.5 million dry metric t/yr for a continuous corn rotation using conventional till in Kansas to more than 97 million dry metric t/yr for a corn-wheat rotation using no-till in Illinois.

Index Entries: Corn stover; wheat straw; rainfall erosion; wind erosion; tolerable soil loss.

Introduction

Current US primary energy consumption is about 102 exajoules (EJ) (97 Quads) and is expected to increase to >137 EJ (130 Quads) by 2020. Transportation fuels produced from oil are projected to account for nearly one-third of the projected energy use by 2020, with nearly 68% of the oil imported from unstable and/or unfriendly countries, resulting in a trade imbalance of more than $206 billion (US $ in $2001). Additionally, the use of fossil fuels for transportation and electricity is a significant contributor of greenhouse gasses such as carbon dioxide, nitrogen oxides, and carbon monoxide (1-4).

*Author to whom all correspondence and reprint requests should be addressed. Appaied Biochemistry and Biotechnoaogy 13 Voa. 113-116, 2004

An important component of becoming less dependent on fossil-based resources is to produce bioenergy and bioproducts from renewable energy resources such as biomass. Domestically produced bioenergy and bio­products have lower environmental impacts, have a higher energy-profit ratio (ratio of renewable energy output to total energy inputs) than tradi­tional fossil fuel technologies, and provide for economic development and enhanced energy security.

Among potential biomass resources that can be used to produce bioenergy and bioproducts are agricultural residues such as corn stover and wheat straw. Corn, soybeans, and wheat are the three largest crops produced in the United States, in terms of both acres and total production. Total production (billion bushels), residue quantities (million dry Mg), and energy density (EJ) produced from corn for grain and spring and winter wheat for the period of 1997-2001 are presented in Table 1.

While residue quantities produced are substantial, only a percentage of them can be collected for bioenergy and bioproduct use. Agricultural residues play an important role in controlling erosion and maintaining soil carbon, nutrients, and soil tilth. Removal of agricultural residues for bioenergy and bioproduct use will require consideration of the quantities that must be left to maintain soil quality. A recent analysis has demon­strated that under appropriate conditions, removal of agricultural residue can potentially occur (5).