A soil conitioner, also called a soil amendment, is a material added to soil to improve plant growth and health. The type of conditioner added depends on the current soil composition, climate, and the type of plant. Some soils lack nutrients necessary for proper plant growth and others hold too much or too little water. A conditioner or a combination of conditioners corrects the soil's deficiencies. Lime is used to make soil less acidic, as is lime-containing crushed stone. Fertilizers, such as peat, manure, anaerobic digestate or compost add depleted plant nutrients. Materials such as clay, vermiculite, hydrogel, and shredded bark will make soil hold more water. Gypsum releases nutrients and improves soil structure. Sometimes a soil inoculant is added for legumes.