Submitted to: Soil Dynamics International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 28, 1999
Publication Date: N/A
Technical Abstract: In latitudes where impending winter conditions force farmers to harvest as soon as the crop is mature, it is often necessary to operate heavy field equipment when the soil is quite wet and easily deformed. Field studies were conducted to (1) determine the extent, depth and persistence to which soils are compacted by wheel traffic of harvest and transport equipment, and (2) measure crop yield response to subsoil compaction over time as mediated by soil water regime and soil texture. Field experiments were conducted in Minnesota, Wisconsin, and Quebec. Plots were compacted with wheel traffic carrying axle loads ranging from 7 - 18 Mg, typical for harvesting equipment in North America. This wheel traffic was applied only at the beginning of the long-term field experiments, after which all wheel traffic on the plots was limited to 5 Mg per axle or less. The heavy wheel traffic altered soil physical properties to a depth of at least 0.6 m. The surface 0.25 m of the soil was then tilled to remove surface compaction. Final grain yield was measured to determine crop response to subsoil compaction over time. In spite of annual freezing/thawing, compaction in the subsoil was not rapidly ameliorated. Depending on location, significant reductions in maize yield (up to 55%) were measured the first growing season after the initial application of heavy wheel traffic. Depending on soil type and climatic factors, there was long-term residual subsoil compaction that significantly decreased maize yield. At one site in Minnesota, maize yield was decreased by 16% twelve years after the initial heavy wheel trafficking. In general the effect of heavy axle load wheel traffic on maize yield increased as axle load, clay content and soil water content increased.