Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/31/2011
Publication Date: 8/9/2011
Citation: Jokela, W.E., Posner, J.L., Hedtcke, J.L., Balser, T.C., Read, H.W. 2011. Midwest cropping system effects on soil properties and on a soil quality index. Agronomy Journal. 103:1552–1562. Interpretive Summary: Intensive row-crop production can lead to soil degradation over time if insufficient crop residue, intensive tillage, or excessive erosion leads to depletion of soil organic matter. Soil quality may be improved by incorporating perennial forage crops or grazing into the rotation, adding manure or other organic sources, and shifting to minimum tillage. We evaluated a range of physical, chemical, and microbial soil properties from six cropping systems in the Wisconsin Integrated Cropping Systems Trial after 18 years of continuous treatments. We also determined the Soil Management Assessment Framework (SMAF), an overall soil quality index. Cropping system treatments significantly affected all soil properties in the 0 to 2-inch soil depth and most in the 2- to 8-inch depth. The pasture treatment had the highest microbial biomass, organic carbon, total nitrogen, readily available nitrogen and carbon, and aggregate stability and had the highest soil quality index. The alfalfa-based systems had higher levels of soil nitrogen, carbon, and stable aggregates than did the grain- based systems, but soil quality indexes were not different. Some physical properties indicate that pasture and the forage phases of rotations have greater soil compaction than corn, probably due to harvesting traffic without subsequent tillage. These results suggest that, while there are significant differences among systems for most soil properties, when well managed, they all maintained soil quality on these productive, prairie-derived soils.
Technical Abstract: Cropping systems may improve or decrease soil quality, depending on the specific crop rotation, nutrient amendments, and tillage practices employed. We evaluated soil properties from six cropping systems in the Wisconsin Integrated Cropping Systems Trial (WICST) after 18 years of continuous treatments. We sampled soils (0-5-cm and 5-20-cm depths) following the corn (Zea mays L.) year of three grain-based systems (continuous corn and two grain rotations), after both corn and alfalfa in two forage-based systems (organic and conventional), and in grass-legume pasture. Extractable P and K, pH, total organic C (TOC), total N, active soil C, potentially mineralizable N (PMN), water-stable aggregates (WSA), bulk density (BD), penetrometer resistance, and total microbial biomass (TMB) were measured, and the SMAF soil quality index (SQI) was determined. The pasture (0-5 cm) was significantly better than all other systems in almost all soil quality indicators and had the highest SQI. The alfalfa (Medicago sativa L.)-based systems had more total N, TOC, active C, PMN, and WSA and higher BD in one or both depths than did the grain based systems but SQIs were not different. Among the grain systems, there was less variation and few significant differences were observed. Within the forage-based rotations, the alfalfa phase had more total N and higher BD than the corn phase, indicating that there is crop-specific variation with these systems. These results suggest that, while there are significant differences among systems for most soil properties, when well managed, they all maintained soil quality on these productive, prairie-derived soils.