What the typical organic gardener needs to amend their garden with often depends on the condition of the original soil. Often, when homes were built, the developers cleared away the native topsoil to level the sites for construction. What is left is a subsoil of limited capacity, but with good potential. When plants are grown in that soil, without amendment, the results are often discouraging. Amending our garden soil is a national pastime.
Many places sell soil amendments to help the gardener grow the best crop they can.
When we look at nature, we notice the constant supply of dead, decomposing material littering the ground. This is the way the soil is constantly replenished. The composting of leaves and grass and non-animal kitchen wastes in our gardens results in the most useful organic material that can be added to our soil. The needs for other amendments vary, but can be determined by soil testing. Organic content is the most important feature.