Texas FFA Nursery Landscape Practice Exam

In poorly drained soils, the lack of adequate drainage leads to saturation with water, which significantly reduces the amount of oxygen available in the soil. Plant roots require oxygen for respiration, a critical process for energy production and overall health. When the oxygen levels are low, root growth can be stunted, and the plants may struggle to absorb nutrients effectively. This anaerobic environment can also lead to root rot and other diseases, which further inhibit plant growth. Consequently, the low oxygen content explains why plants do not thrive in poorly drained soils, as they are deprived of a vital resource necessary for their survival and growth.

While other factors, such as excessive water leading to root engorgement or organic matter levels, can affect plant health, the primary issue in the context of poorly drained soils is the insufficient oxygen available to the roots.