Quantification of compaction effects on soil physical properties and crop growth

A quantitative description of soil compaction effects is required to improve soil management for reducing compaction problems in crop production and environment. Our objective is to provide a review of indices and methods used to quantify the effects of compaction on soil physical properties and crop growth. The paper starts with the description of available methods to quantify stress and displacement under traffic. The following few sections deal with methods and parameters used to characterise the effect of compaction on soil strength, oxygen, water, heat and structural arrangement with consideration of spatial variability. The effect of soil compaction on macroporosity and associated water movement, aeration and root growth is discussed. One section is devoted to integrated systems to measure simultaneously more than one soil physical property. Potential of some advanced developments in computer-assisted tomography (CAT) and nuclear magnetic resonance (NMR) for non-destructive 3D quantification of soil structure, roots and root water uptake as affected by soil compaction is indicated. Finally, some techniques useful for quantifying root and shoot growth, and water uptake in relation to soil compaction are discussed. The models available allow assessment of compaction effects on some behavioural soil properties based on the inherent properties and bulk density of soil. Additional research is required on the effect of compaction on soil structural discontinuities that substantially affect many soil functions and root growth in the whole profile. (C) 2003 Elsevier Science B.V. All rights reserved.