A root will not grow without oxygen. Air exchange in the root zone is essential for root growth. A poor root system provides a poor top growth. Litter will help the soil structure so that a soil has good air exchange. Organic matter has negative charges which will hold positive-charged nutrients such as ammonium, calcium, magnesium, zinc and others.
Sandy particles have no electrical charges to hold nutrients.
Clay, silt and organic matter help hold nutrients in the soil. Too much clay and silt will cause a tight soil evidenced by poor air and water movement in the soil. There is a constant exchange of plant nutrients between organic matter and the soil solution where plant roots pick up nutrients. Organic matter helps increase microorganisms. Microorganisms are very beneficial to soils.