Whether your soil is clay, sand or loam, you can improve its overall structure and fertility by selectively adding organic material. Organic material consists of dead plant and animal matter; as a general rule of thumb, if it was alive at one time, then it counts as organic material and you should be able to add it to your soil. Your goal in adding these materials to your soil is to help them become organic matter, a humus-rich material that provides nutrients for your plants, prevents erosion and improves the ability of your soil to hold water. Sheet composting is one of the simplest ways you can add organic materials to your soil.
Collect organic materials in a pile near the soil you're working with. Aim to gather equal amounts of high-nitrogen materials (typically green materials, such as fresh grass clippings, cow or horse manure, fruit waste and vegetable peels) and high-carbon materials (typically brown materials, such as dead leaves, straw, sawdust, cardboard and old hay).
Prepare the soil for your organic material. Till your soil with a hoe or shovel, turning and loosening the top 3 to 4 inches of dirt.
Shred any large chunks of organic material, such as cardboard, into smaller pieces, ideally less than 1 1/2 inches in diameter. Mix the materials thoroughly in your pile. Spread your organic materials across the surface of your soil in an even layer that is approximately 5 to 6 inches thick.
Mix the organic material with your soil. Although you can use a rototiller, a shovel or hoe works just as effectively and minimizes potential soil impaction that may occur with a rototiller. Turn the soil and blend it thoroughly with the organic material.
Mist the organic material with water from your garden hose. Leave the soil alone for at least six months to allow the organic material enough time to decompose sufficiently before planting time. Till the soil again before you begin planting.