A gardener might have any number of reasons for amending soil. Sometimes the reason is simply wanting to refresh the garden after a long winter. Usually a gardener will want to add soil amendments when planting something new, to help give the plant the best and strongest possible start. This is true whether you are transplanting tiny annuals or young trees. Soil amendments not only improve the physical quality of the soil but can change its pH as well.
Decide which type of soil and what pH is proper for your tree. Some trees thrive in acidic soils while others prefer an alkaline or neutral pH. The Virginia Cooperative Extension suggests that a soil pH range of 6.5 to 7.2 is best for optimal plant growth.
Perform a pH test of the soil in the planting area. Soil pH testing kits can be purchased at gardening centers and nurseries. Most county extension offices offer soil testing services as well.
Purchase the amendments suggested by the results of the soil test. Examples of some soil amendments include compost, rotted manure, lime, or sand.
Remove weeds from the planting area. Weeds compete with the tree's roots for water and nutrients, especially a young tree.
Dig up the planting area to a depth of 8 inches. As you dig, smash any large clods of dirt and remove any debris you turn up, such as rocks and roots.
Add soil amendments according to the size of the planting area. For a tree you will generally add a 1- to 2-inch layer of compost or other organic matter. If you are adding lime or sulfur, follow the rate suggestions on the package.
Mix the amendments into the soil well and proceed to plant your tree.