Relationship between Wheel‐Traffic‐Induced Soil Compaction, Nutrient Availability, and Crop Growth: A Review

Soil compaction, induced by wheel traffic from large agricultural equipment, has been shown to extend well below the depth of plowing, reducing crop growth and yield in many situations. When a soil is compacted, bulk density increases and porosity decreases as larger pores are compressed, producing a soil with a greater proportion of fine pores. The resulting soil has a reduced capacity for the movement of water and air, and offers greater resistance to root penetration. Compaction increases the diffusion rate of nutrients, as soil particles are moved closer together. This effect may, in fact increase nutrient uptake per unit length of root; however, total plant uptake is generally reduced because the increased root penetration resistance reduces root growth. Where aeration is significantly reduced, N availability may decrease because of denitrification, and K uptake may be reduced if respiration within the root is reduced. Plant growth probably is adversely affected because of a combination of these effects, most of which are related to the water status of the soil. Soil compaction is best controlled by reducing vehicle load or controlling traffic. Fertilization may compensate partially for a yield limitation. Subsoiling is generally an unsuccessful method of alleviating compaction. This paper also discusses the effects of soil compaction on soil properties affecting crop production and methods that have been studied to compensate for potential yield reduction.