The current rate of soil erosion exceeds the rate of soil formation, making soil conservation the highest priority in sustainable agriculture and home gardening. Soil is washed away 10 times faster in the United States than it is replenished and 40 times faster in China and India, according to the Center for Earth Leadership.Topsoil is the source of nutritional value for food. There are a number of ways to conserve and improve the soil in a garden.
The American Dahlia Society recommends layering the garden with plant waste that would normally go into the compost or recycling bin. The benefits are "no weeds, less water, saving your back, no machinery, and no chemicals," report dahlia growers Tom Cleere and Steve Nowotarski. Bacteria, fungi, nematodes earthworms and other microorganisms eat the decaying layers of plant material and create beneficial nutrients that enrich the soil. Its structure is improved through the addition of decaying organic materials. Soil is conserved and renewed by the continuing process of decay.
"Composting has the ability to help regenerate poor soils," according to the Environmental Protection Agency (EPA). Adding organic material in the form of compost to soil improves its structure and fertility. Improved structure helps roots grow more easily. Fertility is increased through the nutrients created by microorganisms. Billions of microorganisms are present in small amounts of healthy compost. Composted soil also retains water more easily, which reduces topsoil run-off. Compost can be added to garden soil at planting time, used as a fertilizing side-dressing or as mulch.
Soil is degraded and washed away by unnecessary water flow. Drip emitters and soaker hoses can be installed to control the flow of water to plants. This conserves water and soil. Soil that has adequate organic matter content retains the amount of water the plants need. Creating hydrozones of plants with similar water needs also conserves water and prevents soil erosion.
Mulch is a two- to three-inch layer of organic materials spread around the base of growing plants. Straw, dry leaves, chipped bark and compost are commonly used as mulch. This method helps conserve soil by providing constantly decomposing plant materials and by retaining water. Soil underneath mulch is soft, pliable and fertile.