It can take up to 10 years to build a rich, healthy garden soil, according to the Colorado State Extension. This is especially true if your soil is composed of thick clay. The addition of organic materials, such as manure, compost and peat moss, will help change the texture of the soil and add nutrients. The process of adding soil amendments should begin in the fall.
Perform a soil test using a testing kit purchased at a gardening center, or submit a soil sample to your county cooperative extension office for testing. The results of the test will let you know what types of amendments to purchase. For instance, if the pH of your soil is highly alkaline, the addition of gypsum will help to lower the pH.
Lay down a 3-inch layer of bark chips over the existing soil. Allow the chips to sit on the soil over the winter.
Dig up the soil to a depth of 12 inches in early spring, as soon as the soil is workable. Use the gardening fork or a shovel to crush the soil into finer particles. Remove any debris that turns up, such as rocks and old roots.
Pour the amendment, at the rate suggested by your soil test results, onto the existing soil. Some amendments are measured in inches, others in pounds per square foot. For instance, when establishing a new garden bed a 3-inch layer of compost or well-rotted manure will add nutrients to the soil and aerate it.
Mix the amendment into the soil, using the gardening fork or a shovel to dig it as deeply as possible into the planting area. Generally, 8 to 12 inches is sufficient. Run a rake over the area to level it.
Water the area slowly but deeply. When the water begins to puddle, allow it to drain and then water again lightly. The soil is now ready for planting.