When soils are poorly drained, the air content of the soil is reduced. Poorly drained soils are saturated with water which fills up the pores between the soil particles. As a result, the air content in the soil is reduced, leading to anaerobic conditions that can negatively affect plant growth. Oxygen is required for the respiration of roots and soil microorganisms, and without it, the rate of decomposition can be slowed down. Additionally, anaerobic conditions can lead to the production of toxic substances in the soil that can inhibit plant growth. Therefore, proper drainage is important for maintaining a healthy soil environment for plants to grow.