有机肥指用作肥料的粪便、秸秆等有机物，包含粪肥、堆肥等。有机肥有利于提高土壤的肥力，改良酸碱性土壤、增加土壤透气性和保水保肥功能。

• 粪肥 由动物粪便而来
• 堆肥 各类桔秆、落叶、动植物残体、动物粪便以及少量泥土混合而成的肥料
• 绿肥 用绿色植物，如苜蓿、满江红、水葫芦等作肥料
• 沼气肥 使用沼气池中副产物作肥料，包括各类有机物腐解产生沼气后剩余的沼气液、残渣等
• 变质食物、豆粕、果类残渣

Manure is organic matter, mostly derived from animal feces except in the case of green manure, which can be used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil. Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web. It is also a product obtained after decomposition of organic matter like cow dung which replenishes the soil with essential elements and add humus to the soil.