IMPROVEMENT OF DAIRY FORAGE AND MANURE MANAGEMENT TO REDUCE ENVIRONMENTAL RISK
Location: Environmentally Integrated Dairy Management Research Unit
Title: Cropping system effects on soil quality
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 20, 2010
Publication Date: January 1, 2011
Citation: Jokela, W.E. 2011. Cropping system effects on soil quality. Meeting Proceedings. p. 157-162.
Cropping systems can affect a range of soil properties depending on the specific crop rotation, nutrient amendments, and tillage practices employed. A soil quality index can be use to interpret changes in soil properties and assess improvement or degradation of soil quality. We evaluated a range of physical, chemical, and microbial soil properties in two separate field experiments – a 4-year trial with various cover/companion crops in silage corn and the long-term (18-year) Wisconsin Integrated Cropping Systems Trial (WICST). We also determined an overall soil quality index, the Soil Management Assessment Framework (SMAF). In the silage corn trial we soil-sampled treatments of corn grown with a living mulch of kura clover, interseeded red clover or Italian ryegrass, September-seeded winter rye, or no cover crop. In the WICST experiment we sampled soil in the fall following the corn year of three grain-based systems, after both corn and alfalfa in two forage-based systems, and in a grass-legume pasture. Extractable P and K, pH, total organic C, total N, active soil C, potentially mineralizable N, water-stable aggregates, bulk density, penetrometer resistance, and total microbial biomass were measured, and the SMAF soil quality index was calculated. Use of companion/cover crops in silage corn resulted in some improvement in physical conditions, more microbial biomass, and a somewhat higher soil quality index. In the WICST study, 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, total carbon, and stable aggregates than did the grain based systems. 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 indicate that cover crops in silage corn and well-managed pasture can have a beneficial effect on soil quality as measured by a soil quality index. While there are significant differences among different long-term grain-perennial forage systems for most soil properties, when well managed, there were not great differences in soil quality on these productive, prairie-derived soils.