Nitrogen and Phosphorus Characteristics of Beef and Dairy Manure

Managing livestock manure, and its nitrogen (N), phosphorus (P), and carbon (C) contents, is a major challenge for producers, but it is also an area with high mitigation potential against the negative environmental impact of livestock production. This chapter reviews and synthesizes information on relevant properties of N and P in dairy and beef manure, and how they are affected by diet, climate, and management. The nitrogen use efficiency (NUE) of beef cattle is generally low, as 80 to 90% of the dietary feed N is excreted in manure. Phosphorus is an essential component of cattle diets due to its importance in bone formation, cell growth and differentiation (i.e., DNA and RNA), energy use and transfer, phospholipid formation, and maintenance of acid-base and osmotic balances. Both organic and inorganic N is excreted by cattle. These manure N compounds can be valuable plant nutrients or have adverse environmental effects on air and water quality.