Over recent years, housing for livestock has increased substantially. In many cases, such intensification has lead to larger volumes of stored waste, which are more anaerobic in nature. Farm manure was previously considered part of the natural means of fertilising the land. These larger wastes volumes are chiefly from cattle, pig and poultry and are considered a problem. First in terms, of when and how often to landspread and second, if wastes cannot be spread on the land, how they can be stored or disposed of effectively without risk of transfer to watercourses.
Manure is collected and stored in different forms.
Cattle waste contains 45 kt of P but at lower concentrations than that found in pig or poultry manure. Each of these animals has different ways of digesting and excreting waste. The cow has a rumen to digest plant material and phytase to breakdown inositol hexaphosphate. Phytase is lacking in some animals, such as the pig and chicken, which are monogastric. The absorption of phosphorus by animals is controlled by a range of co-dependent factors that include dietary levels, vitamin D and others, as well as the health and age of the animal.