Balancing the Use of Crop Residues for Biofuels with Impacts on Soil and Greenhouse Gases

by Jessica Bass

The use of crop residues as a second-generation source of biofuels may hold potential to help the United States fulfill its 2022 goal production quota outlined in the 2007 Energy Independence and Security Act. Yet, this annual accumulation plays an important role toward maintaining soil organic carbon (SOC) stocks and reducing soil erosion, protecting field health to sustain year-after-year of yields. Adler et al. (2015) use the DayCent biogeochemical model to analyze the costs and benefits of crop residue removal and use based upon its impact on crop yield, SOC content, and N2O emissions, over the course of twenty years. They examined these relationships with respect to a variety of anticipated treatment options, including: a baseline condition with no residue removal, a sample of 50% residue removal without any replacements, 50% residue removal with a nitrogen replacement equivalent to the amount removed, and a 50% residue removal and equivalent application of a high-lignin fermentation byproduct (HLFB). Continue reading

Cellulosic Ethanol Technically Comes of Age

by Emil Morhardt

Making liquid fuel out of crop waste is, in principal, an extremely good idea. But the ethyl alcohol (ethanol) we add to gasoline—and also drink in vodka, wine and beer—has been made out of edible fruits and grains. Corn ethanol, the main gasoline substitute is made out of the corn kernels which otherwise might become corn meal or tortillas, cutting into the food supply and encouraging conversion of more land into cropland. There have been many studies on the effect of this land conversion on atmospheric CO2 levels, and it appears that it will often be a decade or more before the CO2 released from land conversion will be offset by the substitution of ethanol for fossil fuels. Continue reading