Which characteristic of clay soils can impact plant growth negatively?

The characteristic of clay soils that can negatively impact plant growth is their density and tendency to retain too much water. Clay soils are composed of very fine particles that pack together tightly, which reduces pore space. This dense structure leads to poor aeration, meaning that the oxygen necessary for root respiration can be limited. Additionally, their high water retention capacity can create waterlogged conditions, which can suffocate roots and promote anaerobic conditions that hinder plant growth.

While poor drainage properties is another concern associated with clay soils, the specific combination of density and excessive water retention is critical. This aspect directly affects the balance of water and air in the soil, making it difficult for plants to thrive.