Plants derive nutrients, oxygen and water from the soil. The better the soil is at providing these three things, the better your garden will grow and the more food it will produce. Preparing the soil before you plant your garden will help your garden realize better yields and resist disease. If you have poor soil, you can supplement it to improve its quality. Each year you work in your garden, the soil will improve.
Dig the soil to a depth of at least 1 foot. Drive the blade of the shovel straight down into the soil and turn the soil over. Break up clods with the shovel blade or a hoe. Rake the area free of rocks and tree roots.
Test the soil pH, using a test kit. The ideal soil has a pH of about 6 to 6.8, according to Iowa State University. If your soil registers below 7, it's acidic. If the soil pH is above 7, your soil is alkaline. Knowing this will help you know how to improve the soil.
Add compost to the soil. Compost adds nutrients, increases the soil's ability to hold water, and makes the soil looser and fluffier. Dump the compost on top of the soil and dig it in with the shovel. The University of California recommends adding compost equal to at least 30 percent of the soil's volume, or 1 inch of compost for every 3 inches of soil.
Adjust the soil pH. If you soil is too acidic, add lime. If the soil is alkaline, add powdered sulfur. The amount of these additives you'll need depends on your soil's pH and whether the soil is clay, loam or sand. Sprinkle the material on top of the soil and rake in, distributing it evenly.
Add nitrogen. Nitrogen, along with phosphorus and potassium, is one of the three elemental nutrients plants need to grow. Iowa State University recommends using manure to add nitrogen to the soil. The nitrogen will be released slowly as the manure breaks down. Iowa State University recommends adding 10 lbs. of chicken manure or 20 lbs. of cow manure for every 100 square feet of garden. Work the manure into the soil with the shovel and hoe.