Since the proportion of solid matter in a given volume of soil/substrate is relatively constant, the proportion of air-filled pores and water-holding pores is in a close reciprocal relationship: very high soil water content (especially in soils with high clay content) leads to an impediment of gas exchange (see above).

However, soil water content has an influence not only on substance conversion but also on the physico-chemical process of nutrient transport to the root (diffusion and mass flow).

An excess of nutrient elements can be counteracted by flushing the soil/substrate with large quantities of water, thereby reducing the concentration in the root zone. This does not immediately eliminate the excess within the plant, but it improves the growth conditions for young organs.