Inorganic amendments include vermiculite, perlite, tire chunks, pea gravel and sand. Not all of the above are recommended by Colorado State University. These are merely examples. Wood ash, an organic amendment, is high in both pH and salt. It can magnify common Colorado soil problems and should not be used as a soil amendment.
Organic amendments increase soil organic matter content and offer many benefits.
Many organic amendments contain plant nutrients and act as organic fertilizers. Organic matter also is an important energy source for bacteria, fungi and earthworms that live in the soil. If your soil has less than 3 percent organic matter, then apply 3 cubic yards of your chosen organic amendment per 1,000 square feet. To avoid salt buildup, do not apply more than this. Retest your soil before deciding whether to add more soil amendment.