Using organic materials such as soil conditioners tends to improve the ability of a soil to retain moisture. Garden mulches also help conserve soil moisture. Organic matter used for mulching and soil conditioning is constantly being oxidized (used up) by natural decomposition. To be depended on as a soil conditioner requires constant replenishment; when each new crop is planted. During drought years, plants perform better in soils rich in organic matter than in soils low in organic matter.
Try to wet your soil thoroughly each week, so that the root zone is moistened. No irrigation is necessary if rainfall is sufficient.