Grazing and Baling of Corn Residues Across a Precipitation Gradient: Implications on Soil Ecosystem Services

Abstract

Grazing and baling of crop residues are common practices in integrated crop-livestock systems, but their impacts on soil ecosystem services are not well understood on regional scales. This dissertation evaluated the impact of corn residue grazing and baling on soil properties under different soil types, cropping, irrigation, and tillage systems across six sites along a precipitation gradient in Nebraska for three years. Results indicate that corn residue grazing had small or no effects on soil properties in the short term. Residue baling decreased soil water content by 8 to 32% and increased wind erodible fraction by 22 to 56% but did not affect other soil properties compared with the control across Nebraska. These results indicate that baling had greater effects than grazing. The impact of residue baling on soil water content and wind erosion persisted throughout the year based on detailed data from one of the sites. Modeled results indicated wind erosion potential can be can be controlled if residue cover is above 20%. An improved equation (Erodible fraction = 84.3+2.64 × silt - 0.30 × clay - 7.43 × organic matter-0.15 × residue cover) is proposed for Nebraska soils to estimate wind erosion potential. Residue grazing and baling showed no influence on greenhouse gas emissions, which were measured at one of the sites. When the daily gas emissions were summed to obtain cumulative emissions, residue grazing increased CO₂ emissions by 15% compared with the baling, whereas N₂O and CH₄ emissions did not differ. Increased CO ₂ emissions indicate increased microbial activity. It appears that corn residue grazing does not impact soil ecosystem services in the short term. Even in the long term, we did not observe any negative impact of corn residue grazing on soil properties at one of the sites in eastern Nebraska although spring grazing slightly increased soil compaction. The slight increase in compaction was, however, below the threshold limit (≤ 2 MPa) to limit crop production. Overall, corn residue grazing can be a viable practice in integrated crop-livestock systems, whereas residue baling may negatively impact some of the soil ecosystem services (e.g., wind erosion).