Choose an amendment that decomposes slowly. Choose a combination of amendments. Decomposition rate of various amendments. Soil Texture Soil texture, or the way a soil feels, reflects the size of the soil particles. Sandy soils have large soil particles and feel gritty.
Clay soils have small soil particles and feel sticky.
Both sandy soils and clay soils are a challenge for Gardeners. Loam soils have the ideal mixture of different size soil particles. When amending sandy soils, the goal is to increase the soil's ability to hold moisture and store nutrients. To achieve this, use organic amendments that are well decomposed, like composts or aged manures. With clay soils, the goal is to improve soil aggregation, increase porosity and permeability, and improve aeration and drainage.