Manure consists of three basic elements critical to plant health: nitrogen, phosphorus, and potassium. Nitrogen allows plants to produce the proteins needed to build living tissue for green stems, strong roots, and lots of leaves. Phosphorus helps move energy throughout the plant, especially important in maturing plants. Potassium aids plants in adapting sugars needed in growth and is especially helpful in root crops. Together, these three elements form that magic formula, N-P-K, the backbone of all fertilizers, man-made or organic. Manure also contains large amounts of humus, a wonderful soil amendment. Humus is simply the bulky, fibrous material that comes from plant fibers and animal remains and is valuable in several ways: it gives better tilth to clay soils; supplies food for soil flora and fauna; preserves moisture during dry spells, while ensuring good drainage during wet times; and it is a storehouse for nitrogen in the soil. In short, humus acts like a reservoir, allowing nutrients to work.