Title: The impact of corn residue removal on soil aggregates and particulate organic matter Authors
Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 12, 2014
Publication Date: February 12, 2014
Citation: Osborne, S.L., Johnson, J.M., Jin, V.L., Hammerbeck, A.L., Varvel, G.E., Schumacher, T.E. 2014. The impact of corn residue removal on soil aggregates and particulate organic matter. BioEnergy Research 1-9. doi:10.1007/s12155-014-9413-0. Interpretive Summary: Corn residue is being considered as a possible feedstock for biofuels production, although the long-term impacts of removing this residue on soil health are not well understood. Above- and below-ground crop residues are the soil’s main sources of organic materials that are key components of soil formation. Organic matter provides a source of carbon that increases soil carbon storage. It becomes the glue that holds soil particles together, forming aggregates. It also supplies plants with nutrients, increases soils’ ability to hold water, and helps reduce erosion. In order to determine the short and long term effects of removing corn residue on soil health, we evaluated three different field studies established in South Dakota, Minnesota and Nebraska. Trends were consistent at all three locations. When corn residue was removed from the soil surface, there was a steady decrease in the amount of soil organic matter, indicating a possible decrease in soil health. There was a shift toward smaller soil aggregates when crop residue was removed, increasing the risk of wind and water erosion. This change in soil aggregate size could trigger lower soil water infiltration and lower soil water holding capacity that could impair crop growth. Incorporation of cover crops or additional fertilizer nitrogen appears to decrease some negative effects of residue removal by providing a source of additional carbon through increased plant growth either from an increase in inseason crop growth or from an additional crop (cover crop). Within these three studies, removal of corn residue without the use of cover crops or additional nitrogen had a negative impact on soil physical properties, illustrating the importance of crop residue to maintain our soil resource. Without crop residue on the soil surface, soil organic matter and soil aggregation decreased, limiting the soil’s ability to resist soil erosion, provide soil water to the crop, and store nutrients. This research contributes to the USDA-ARS-REAP project.
Technical Abstract: Removal of corn stover as a biofuel feedstock is being considered. It is important to understand the implications of this practice when establishing removal guidelines to ensure the long-term sustainability of both the biofuel industry and soil health. Above- and below-ground plant residues are the soil’s main sources of organic materials that bind soil particles together into aggregates and increase soil carbon storage. Serving to stabilize soil particles, soil organic matter assists in supplying plant available nutrients, increases water holding capacity, and helps reduce soil erosion. Data obtained from three Corn Stover Regional Partnership sites (Brookings, SD; Morris, MN; and Ithaca, NE) were utilized to evaluate the impact of removing corn stover on soil physical properties including dry aggregate size distribution, erodible fraction (EF), and soil organic matter components. Each site consisted of a combination of three residue removal rates (low - removal of grain only; intermediate - ~50% residue removal; high- maximum amount of residue removal). Results showed that the distribution of soil aggregates was less favorable for all three locations when residue was removed without the addition of other sources of organic matter such as cover crops. Additionally, we found that when residue was removed and the soil surface was less protected, there was an increase in the EF at all three research sites. There was a reduction in the EF for both the Brookings and Ithaca sites when cover crops were incorporated or additional nitrogen was added to the system. Amounts of soil organic matter (SOM), fine particulate organic matter (fPOM) and total particulate organic matter (tPOM) consistently decreased as greater amounts of residue were removed from the soil surface. Across these three locations, removal of crop residue from the soil surface had a negative impact on measured soil physical properties. The addition of a cover crop or additional nitrogen helped to reduce this impact as measured through aggregate size distribution, EF and soil organic matter components.