Soil respiration and nitrous oxide production in distillers grain and glycerol amended soil
Applying by-products of biofuel production to soil may be an alternative use to take direct advantage of nutrients and carbon contained within. Ethanol production results in distiller grain and biodiesel produces glycerol as by-product. However, no information currently exists on the effects of adding these amendments on evolution of carbon dioxide and nitrous oxide from soils, yet is important to complete our understanding of potential impacts of biofuel production on greenhouse gas budgets as well as soil quality. Pots containing soil amended with different rates of wet distillers grain, thin stillage, and glycerol were placed in incubation chambers and incubated for 10 days. Treatments of alfalfa powder and urea were added at the same rates of total N as the by-products for comparative purposes. Carbon dioxide and nitrous oxide evolved from amended soil was measured. The alfalfa powder and wet distillers grain resulted in the greatest evolution of CO2 from the soil, with the thin stillage resulting in less CO2 evolved per unit of nitrogen added. Addition of nitrogen fertilizer along with glycerol enhanced microbial activity and decomposition. Per unit of nitrogen added, urea tended to result in the greatest N2O produced, followed by wet distillers grain and thin stillage, with glycerol and dehydrated alfalfa resulting in the lowest nitrous oxide production.
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