Thirteen-year stover harvest and tillage effects on soil compaction in Iowa

Corn (Zea mays L.) stover is an abundant biomass source with multiple end-uses including cellulosic biofuel production. However, stover removal may increase soil compaction by reducing organic matter inputs and increasing vehicle loads during harvest. While numerous studies have reported stover removal impacts on soil physical quality, few have assessed the role played by traffic compaction. Our objective was to quantify subsurface soil compaction after 13 years of chisel plow versus no-till management and no, moderate (3.5 +/- 1.1 Mg ha(-1) year(-1)), or high (5.0 +/- 1.7 Mg ha(-1) year(-1)) stover harvest rates. Penetration resistance was measured in most- and least-trafficked interrow spaces. Chisel plowed plots with moderate and high levels of stover removal had higher penetration resistance in trafficked areas relative to least-trafficked areas, whereas there was no evidence of traffic compaction when stover was retained. Traffic compaction did not negatively impact yields, which were greater with high levels of stover removal compared to no removal. The no-till practice led to very small increases in penetration resistance with wheel traffic and had no evidence of increased compaction with residue removal. This lack of traffic compaction indicated soils under no-till practice have a higher load-bearing capacity than soils under chisel plow practice. Overall, there were no yield-limiting effects of tillage practice or stover removal, and no evidence of soil compaction below the plow layer, suggesting stover removal with both tillage practices can be effectively employed without detrimental effects on plant or soil health.