The soil particles of clay soil (also called as black soil because of its color) are very minute and are tightly bonded to each other. So tightly are they attached to each other that it is difficult for both air and water to penetrate. Water percolates very slowly through the soil. Clay soil is a very fertile soil, full of minerals (nutrients).
Now that we have understood the soil properties lets understand how the stress works.
Air: As mentioned earlier the air penetrates very slowly through this soil. Hence inadequate supply of air causes a stress on plant.
Water: Water percolates very slowly through this soil. There is a high possibility of excess water clogging around the roots of the plants. Hence excessive water supply causes a stress on plant.
Nutrients: clay soil is one of most mineral-rich soil and plants receive ample of nutrients. There is no stress on plant as far as nutrients is concerned.
Synopsis: Clay soil creates two stresses on plants and hence is not the most ideal one. However these stresses can be corrected/removed with composting. We will study about it in detail in my upcoming posts.