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Quantitative characterization of the compaction of Ontario soils by deflated tractor tires and tracks

Principal Investigator: Richard J. Heck

Research Institution: University of Guelph

Timeline: April 2019 – December 2022   

Objectives:

  • Further our understanding of the relative impact of tire- and track-based agricultural machinery traffic on topsoil and subsoil compaction in Ontario.
  • Quantify changes in topsoil and subsoil structure, induced by machinery operating on either tracks or variably inflated tires, with specific consideration for soil texture, cropping history and moisture status.
  • Assessment of the relative impact of compaction consequences on soil physical properties known to influence crop performance.
  • Identify quantitative indicators of soil 3D microstructure, as tools for evaluating the degree of soil compaction.

Impacts:

  • With case studies to highlight the relative impacts of available traction technologies on soil compaction, Ontario farmers will be able to more effectively select a solution to extend their window of operations on the field, while still minimizing undesirable impacts on soil structural quality.
  • Further insight on the relative vulnerability of different soils to structural deterioration, as a function of conventional and alternative management, will guide the refinement of BMPs and associated policies.
  • Enhanced understanding of the impact of compaction forces on soil profile structure, as a function of soil type and management, will be useful for guiding improvements by farm equipment manufacturers, and help machinery retailers more appropriately target clients in Ontario.
  • Expanded knowledge on the behaviour of selected soil types, under conventional and alternative management systems, with respect to their structural dynamics, which influences hydrophysical properties and ultimately soil health, will help guide future agroecosystem research.

Scientific Summary:

Surface and subsurface compaction due to machinery traffic continues to be a major problem facing Ontario agriculture. Structural degradation influences soil hydrophysical behavior, typically reducing aeration, thereby impacting soil biological activity (including root development and soil exploration), and ultimately impacting crop performance. With the trend towards larger farms, more massive equipment, and the increasing unpredictability of climate, the risk of soil compaction is increasing. In response, many producers are considering track-based tractors and implements, or remotely activated tire deflation/re-inflation systems for their machinery. The impact of such solutions, relative to soil texture, management system (tillage, rotations, etc.) and soil moisture status is still not fully understood, especially in terms of soil structural quality.

This research will merge advanced in-field pressure sensing techniques and penetrometer resistance, with high-resolution x-ray CT imaging and micro-penetrometer profiling of intact cores, with conventional soil physical characterization (density, moisture retention) to understand the impact of compaction pressure on topsoil and subsoil structural changes. Compaction trials will compare track-equipped tractor/load assemblies, with wheel-based (employing both upper and lower recommended inflation pressures) equivalents. The study will be run on collaborator fields, representing coarse, medium and fine-textured soils, considering conventional and BMP, all on zero-tilled soils. Results will help producers in their selection of solutions (to balance field accessibility while minimizing compaction risks), guide the refinement of BMPs for structural quality, inform machinery manufacturers and retailers, and further our fundamental understanding of soil behavior.

External Funding Partners:

This project is funded  by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), through the Agri-Food Innovation Alliance.