Soil anchors the plant, provides air, water, and mineral nutrients necessary for plant health and growth. Soil is also home to worms, insect predators and scavengers. Multitudes of important microorganisms that are beneficial either directly as with mycorrhizal fungi or indirectly by breaking down organic matter into its elemental components, are found in soil. Organic matter is a storehouse for nitrogen, sulfur, and phosphorus. It increases the cation exchange capacity of soils, and serves as a buffer in chemical reactions.
Organic matter is important in soil tilth.
It increases the heat absorption in soils and the porosity of heavy, clay soils. Organic matter decrease leaching, erosion, and water run-off. Vegetables are fast growing, with a limited root system. Vigorous, uninterrupted growth is important. Quality for leaf crops depends on tender, succulent growth promoted by ample water and nutrient levels.