Vegetable roots absorb nutrients from healthy topsoil with high organic content. Nutrients are created in the soil by the billions of tiny living organisms that we call "organic matter." Organic matter also gives soil structure to hold roots. According to Cornell University Extension, sandy soils should contain 2 to 3 percent organic matter, and clay soils 4 to 5 percent. Organic matter consists of plant and animal residue that is decayed or decaying. There are several easy ways to maintain garden soil with adequate amounts of organic matter.
The easiest way to create a supply of organic matter for the garden is with a compost pile. Kitchen vegetable and fruit scraps, newspaper and office paper, yard and lawn clippings and dry leaves decay when they are mixed with air and water in a pile. The decayed materials become a dark, rich crumbly soil. When compost is added to garden soil the organic matter content is increased and soil becomes healthier. Many local garden centers and city government recycling programs have workshops about composting.
Mulch is a layer of material spread around a plant base to conserve water, suppress weeds and add organic matter to the soil. Materials commonly used for mulch include straw, dry leaves, dry grass clippings and compost. The mulch slowly decays over the growing season and adds its organic materials to the soil. Organic farming practices often focus on leaving harvested plant residue on the ground as a mulch which protects the soil structure and continues adding nutrients.
The no-till gardening method strengthens soil structure by continually adding organic matter without disrupting it by digging or tilling. Materials such as compost, leaves, grass and mulch are spread on soil to create layers of decomposition that slowly enrich the soil. The American Dahlia Society says the no-till method "is less work and much less cost than a conventional garden. We let Mother Nature do the tilling---fertilizing and weed control."
A mulch mower allows grass clippings to remain on the lawn when it is mowed. The clippings decay and provide nutrients to soil while they protect it from erosion. The collection bag can be easily removed from the mower to allow grass clippings to drop to the lawn. Lawn soil that is continually enriched with organic matter also helps produce oxygen and replenish groundwater supplies.