Effects of Soil Compaction

Structure

• Soil compaction damages soil structure. Soil structure is based on the ability of soil particles to cling together. When compaction occurs, these small aggregates and clods are crushed. Reduced soil structure due to compaction causes a decrease in the water-holding capacity of the soil and the ability for plants to grow. Plant roots need good soil structure for their roots to find purchase on and to penetrate deep into the soil.

Soil Density

• Soil compaction causes reduced soil porosity. Decreased pore space in the soil increases the density of the soil. Soil density is measured by its bulk density. Increased bulk density leads to many problems relating to compacted soils such as erosion and poor plant growth. Depending on the percentages of sand, silt and clay in a soil, the amount of bulk density increase will harm soils differently. This means that there is no specific soil bulk density that will lead to plant fertility decline and erosion.

Plant Fertility

• Plants growing on compacted soils are small and unhealthy. Because their roots cannot penetrate deep into the soil to access greater amounts of water and nutrients, they are unable to grow as large as they normally would. Without proper nutrients and water, they are more susceptible to disease and pests. Compaction of crop lands is one of the main causes of decreased yields. During dry periods, plants are particularly susceptible to problems caused by soil compaction.

Water and Nutrients

• When the pore space of soil is reduced by compaction, there is less area for nutrient-rich water to be stored in the soil. Because of compaction a soil will hold less water and water will more readily drain off of the surface rather than be absorbed. When water drains off the soil it can cause damaging erosion. Erosion can carry away the top fertile layer of a soil. Once an erosion furrow begins due to soil compaction, it can quickly expand during a heavy rainstorm and strip nutrients and rich soil away. Damage from erosion caused by soil compaction is very difficult to remedy.