Manure nitrogen crediting and management in the USA: survey of university faculty

摘要

Livestock production, and particularly manure management, has received environmental scrutiny for years due to potential nitrate contamination in ground and surface waters. During the 1990s, many land grant institutions developed and conducted research and extension programs related to the management and crediting of manure N. To assess the current status of manure N crediting and management in the USA, a national survey of university faculty considered to have expertise in manure issues was conducted. A four-page mail survey was sent to one person in each state to provide qualitative and quantitative information regarding manure N management. A response rate of 86% was achieved. Groundwater and surface water quality are perceived as the top environmental ramifications of manure N management regardless of animal species. Manure N crediting for cropland is highest for poultry operations and lowest for beef operations. Approximately 45% of poultry manure is properly credited, compared with only 18%of beef manure. In addition, manure N crediting is overwhelmingly viewed as improved compared with 5 years ago. Manure N crediting components being emphasized include manure testing, soil N testing, and spreader calibration. Management strategies beingimplemented include writing manure management plans, reduced application rates, and manure injection/incorporation. Regulation - either existing, proposed, or future - is perceived as the primary reason (61%) for producers to better manage their manure.More states will regulate their livestock enterprises via a permitting process in the future, and the trend in developing nutrient plans is toward using a combination N and P standard, rather than solely an N standard. Although N issues have been a focusof manure management in the past, P issues have escalated in the 1990s in terms of environmental importance.