Poor soils don’t cope well with high rainfall –water retention can saturate the soil which damages plants and affects plant growth.
High clay content, low permeability, top-soils and sub-soils of low quality can all lead to soggy top-soil in cool growing seasons. Sub-soils may be dense and impermeable, such that the volume of water on the surface can’t move away without causing erosion or takes ages to evaporate, leaving minerals leached onto the surface of the soil. This is most common in the southern hemisphere in the colder months of July and August when there is slower evaporation.
When the ground is soggy, the aeration of the soil is lower, nitrogen is lost from the soil and the leaves of plants can yellow, restricting their healthy growth. Damage also occurs to the roots of the plants – water retention in the soil actually inhibits the roots’ ability to absorb nutrients and (ironically) water. These problems lie with the soil and can occur whether the ground is flat or on a slope.