Recycling of manure and organic wastes. A whole-farm perspective

As worldwide agricultural production increases, it tends to become concentrated on increasingly larger units. Livestock produce large volumes of manure which, like imported waste materials and crop residues, are a source of valuable plant nutrients and renewable energy, but also a potential threat to the environment and human health. This article discusses briefly the need to assess recycling of organic wastes and manure using a whole-farm approach to avoid a situation where the introduction of new technology and management to regulate one source of pollution will aggravate other environmental impacts downstream in the manure management chain on farms. Some examples of manure N and C turnover are discussed as examples of on-farm interactions.