How does water retentivity and drainage of soil affect the quality of soil?
Different plants like different amounts of water in the soil. So you have plants which stand in water and plants which can do well with just a pint of water. So the soil quality with reference to drainage must take into account the plant you plan to grow in it. Soils which have high drainage let go of the minerals that plants need for their healthy growth. On the other hand too much water retention is not preferred by many plants as it obstructs oxygen to the roots. Yes roots need oxygen to breathe and grow. Lack of oxygen to the roots can cause it to die. Most good potting mixes make use of a mix of different ingredients which give a balance of both water retention and drainaage. The aim for most gardeners would be to create a loamy soil with the necessary organic minerals.
