What Happens to Plants When the Soil Becomes Compacted?

Good Soil

• The best soil for plants contains minerals, organic material, air and water, each of which plays a specific role in helping plants to grow. Minerals make up 45 percent of the total volume of good soil. The minerals are made up of equal parts of clay, silt and sand particles. Five percent of the soil is organic in the form of plant and animal materials. The final half consists of equal parts of air and water.

Compacted Soil

• In good soil, the air and water exists within voids in the soil. Voids are similar to small pockets of empty space. Plant roots use the voids to expand. If there are no voids in the soil, then the soil will not be able to support air or water and roots will not have room to grow. Compacting soil collapses the pockets of empty space where water and air could flow previously. Compacted soil is dense because it consists almost solely of solid matter.

Effect on Roots

• Plants in compacted soil do not have space for their roots to grow. The roots do not have access to water or air, nor are they able to absorb nutrients from the soil. Water is more likely to roll off the surface of the soil than it is to soak into the soil where the roots can access it. If a plant cannot absorb water, air or nutrients through its root system, it will languish and eventually die.

Loss of Nutrients

• Compacting soil kills the microorganisms in the soil. Without a sufficient amount of oxygen in the soil, microbes use air faster than diffusion can replace it. Under optimal conditions, organisms that live in soil exchange oxygen for carbon dioxide. Water dissolves the carbon dioxide and creates a solution that reacts with the minerals in the soil. The resulting mixture forms compounds that are available for plants to use as food for growth. In compacted soil, plants do not have access to food and eventually die.