Compost helps sandy soil retain water and nutrients.
Compost loosens tightly bound particles in clay or silt soil so roots can spread, water drain & air penetrate.
Compost alters soil structure, making it less likely to erode, and prevents soil spattering on plants—spreading disease.
Compost can hold nutrients tight enough to prevent them from washing out, but loosely enough so plants can take them up as needed.
Compost makes any soil easier to work.