Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 10, 2007
Publication Date: August 13, 2007
Citation: Russelle, M.P. 2007. Nitrogen dynamics in integrated crop-livestock systems. In: International Symposium on Integrated Crop-Livestock Systems, August 13-15, 2007, Curitiba, Brazil. CDROM. Technical Abstract: Agriculture has been utterly transformed by the availability of manufactured fertilizers that are inexpensive and easy to transport and handle. Fertilizers severed the need for livestock and poultry manure in crop production. Improved transport systems have allowed farmers to utilize distant markets, encouraging farm specialization and independence. Specialization and growth in productivity have led to disrupted and inefficient N cycling. Re-integrating crop and livestock farming, either within farms or among farms, can improve both N utilization and recycling, and can help reverse soil quality degradation, both from soil organic matter losses and excessive nutrient accumulation on livestock farms. There are tremendous opportunities to help agriculture transform into integrated systems that are economically and ecologically beneficial, and that are better able to meet both private and public goals. This paper summarizes key sources and products of N cycling, examples of within-farm and among-farm N cycling, and ways to achieve high N use efficiency in integrated crop-livestock systems. Sustainable solutions to specialization of agriculture could be achieved by rearranging crop and livestock enterprises to reduce transport distances and take advantage of synergies, such as improved crop rotations for disease control, improved soil tilth with manure application, and direct nutrient exchange among crop and livestock farms. Beyond our lack of an adequate knowledge base, it also is unlikely such a rearrangement of farming will occur in the absence of manure marketing systems and significant government regulations or incentives.