Understanding the spatial heterogeneity of cattle locations and its effects on subsequent crop yield in an integrated corn-cattle system

Abstract. Integrated crop and livestock systems have been suggested as a promising means for diversifying agricultural production. In the Midwestern U.S. Corn Belt, tremendous amounts of corn residues can accumulate on the land after harvest. Utilization of residues left in the field as a nutrient source for cattle can be a viable approach to reducing feed cost; however, the effects of directly grazing corn residues on croplands are unclear. Previous studies have shown uneven spatial distributions of cattle locations during grazing, which may potentially lead to spatially heterogeneous impacts on lands. This study seeks to provide a comprehensive understanding of impacts of grazing strategies on spatial patterns of cattle locations during corn residue grazing in central Illinois, and assess potential effects on subsequent crop yield. A GPS tracking system was implemented to track cattle locations during corn residue grazing experiments on an integrated corn-cattle farm from 2012 to 2014. Two grazing management strategies (continuous and strip grazing) were compared to ungrazed areas in a randomized complete block design with three replications. Spatial analysis tools were utilized to quantify land occupancy rates by cattle and identify factors that affect cattle locations. Areas around water tanks and feeders were identified as heavily trafficked regions. Social interactions among cattle were suggested as another factor that affects cattle locations. Preliminary results suggested that no differences in baseline yield were detected before cattle were introduced into the crop system. After fall crop residue grazing experiments were implemented for two years, no significant differences in subsequent crop yield were detected amongst all three treatments. However, grazing may have spatially heterogeneous impacts on subsequent crop yield, as highly trafficked areas were associated with lower corn yield as compared to other regions after the grazing experiment was implemented on the farm. This implies that caution should be exercised to avoid negative impacts when integrating corn and cattle operations through residue grazing. Scientific models and decision support are, therefore, suggested as a viable approach to facilitate the development of best management practices for integrated crop-livestock systems.