Submitted to: Soil Science Society of America Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/20/2003
Publication Date: 1/1/2004
Citation: JOHNSON, J.M., REICOSKY, D.C., SHARRATT, B.S., LINDSTROM, M.J., VOORHEES, W.B., CARPENTER-BOGGS, L. CHARACTERIZATION OF SOIL AMENDED WITH THE BY-PRODUCT OF CORN STOVER FERMENTATION. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. 2004. V. 68. P. 139-147. Interpretive Summary: Biofuels are a domestic and renewable energy source. A renewable energy source can replace or supplement reducing dependence on foreign energy supplies. The corn residue after grain harvest can be used to make ethanol, a biofuel. After the ethanol is produced, the remaining by-product is about 70% lignin. Lignin is a complex molecule found in plant cell walls, which is difficult for fungi and bacteria to breakdown. Lignin is about 65% carbon (C). Corn stover on the field is important for erosion control, providing plant nutrients and providing soil C. Removing the corn residue from the field may contribute to more erosion and loss of soil C. It was hypothesized that adding this by-product to soil may reduce some of the negative effects of removing corn residue. Many soil properties were monitored on soils, which were treated with corn residue or by-product. Inferences were made on the ability of the by-product to improve/stabilize these soil properties. One of these parameters was humic acid, which is an indicator of soil organic C. Another parameter was aggregate stability, which is an indicator of how well soil can resist erosion. Both of these parameters increased when the by-product was added to the soil at a rate equivalent to 5 ton/acre. This information is important to the US-DOE in determining all aspects in the feasibility of using corn residue for ethanol production. The use of corn residue as a fuel potentially provides an additional commodity for farmers and aids in reducing dependence on non-renewable energy sources. Thus, this research has social, environmental and economic ramifications.
Technical Abstract: Corn (Zea Mays L.) stover is a potential biofuel; however, removing residue can increase the risk of erosion and reduce soil organic matter. After corn stover fermentation, the remaining by-product is about 70% lignin. Lignin and its breakdown and condensation products may play an essential role in stabilizing soil structure. A column study was conducted to determine if return and incorporation of this by-product to agricultural soils might offset some of the negative impacts of stover removal. Soil was collected from a toe slope (non-eroded) and a shoulder slope (severely eroded) within a Svea (fine-loamy, mixed, superactive, frigid Pachic Hapludoll). Soil was either not amended (control) or amended with corn stover, 0.75, 3.0 or 6.1 g by-product kg**-1 and packed into columns. Soils were incubated for 123 d at ambient temperature with an initial water-filled pore space (WFPS) of 60% and drying cycles to 35% WFPS. Compared to the control, amending soil with 6.1 g by-product kg**-1 increased CO2 flux by 68% and increased soluble C and microbial biomass C both by about 20%. In the severely eroded soil, humic acid concentration (r**2=0.84, p<0.0001) and aggregate stability (r**2= 0.35, p< 0.001) increased linearly with increased by-product concentration. Water-holding capacity, bulk density and aggregate size distribution were not changed by soil amendments. Careful management of stover removal (avoiding eroded or erosion prone areas) and selective placement and rates of the by-product could contribute to a sustainable use of corn stover for ethanol production.