Nitrogen and phosphorus characteristics of beef and dairy manure

Authors: PAGLIARI, PAULO - University Of Minnesota; WILSON, MELISSA - University Of Minnesota; Waldrip, Heidi; He, Zhongqi

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2019
Publication Date: 10/24/2019
Citation: Pagliari, P., Wilson, M., Waldrip, H., He, Z. 2019. Nitrogen and phosphorus characteristics of beef and dairy manure. In: Waldrip, H.M., Pagliari, P.H., He, Z., editors. Animal Manure: Production, Characteristics, Environmental Concerns, and Management. ASA Special Publication 67. Madison, WI: American Society of Agronomy and Soil Science Society of America. p. 45-62.

Interpretive Summary: The manure from beef and dairy cattle represents an important source of nitrogen and phosphorus for crop production. However, research has shown that the characteristics of the manure (a combination of urine and feces) from cattle can vary greatly depending on diet, animal production status, nitrogen and phosphorus intake, animal characteristics, and manure management. Manure has been used as a crop fertilizer since the beginning of agriculture. It provides plants with valuable nutrients necessary to produce food for both human and livestock consumption. In addition, the use of manure as fertilizer is a way of recycling nutrients and promoting a sustainable food production system. However, problems can arise when manure is applied improperly. This book chapter outlines the specific nitrogen and phosphorus characteristics of beef and dairy cattle. The most cost-effective method of managing manure nitrogen and phosphorus is through diet manipulation, where nutrients are fed to meet, but not exceed, animal requirements. Other alternatives include manure treatment systems, such as anaerobic digestion or microbial remediation, to remove and recycle excess nitrogen and phosphorus from beef and dairy manure. This chapter is intended to provide comprehensive data on the nutrient contents of different cattle types and under differing manure management systems. In addition, methods of reducing nutrient losses and increasing manure fertilizer value are discussed. These results are of interested to consultants and operators of confined cattle related operations.

Technical Abstract: The ever-increasing global population puts enormous pressure on the food production systems by always demanding increased food production. The amount of milk produced in the US for the last four years has increased on average by 1,100 metric tons per year, with the number of milking cows (Bos taurus) increasing by approximately 41,000 animals over the same time frame. Managing the manure produced by beef and dairy operations is a major challenge due to potential negative impacts on the environment. Most of the nitrogen (N) required by animals is provided in the form of dietary protein. In general, large quantities of consumed N (as much as 95%) can be excreted by cattle as urine and feces. One option to mitigate environmental N losses is to decrease manure N content, which is generally done by altering the dietary crude protein content or diet constituents. Feeding N above animal requirements generally results in increased urinary N excretion, which can then be lost to the atmosphere as ammonia or nitrous oxide. This represents a loss of valuable N that could be better utilized as crop fertilizer. Another key nutrient excreted in beef and cattle manure is phosphorus (P). Manipulation of dietary P levels in cattle can be problematic, as diets that contain insufficient P can be dangerous for lactating cows: diets containing less than 0.31% P can leads loss of bone structure as P is translocated from bone to produced milk. Manure treatment systems can be used to help minimize potential issues related to nutrients from manure. Anaerobic digestion is an option, but this practice has potential to increase the levels of inorganic P and N in the manure. Lastly, using microorganisms to remove nutrients from manure is a promising approach, but much work is still needed for this practice to gain the trust of farmers.