|Graham, P - UNIVERSITY OF MINNESOTA|
|Allan, D - UNIVERSITY OF MINNESOTA|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 22, 2001
Publication Date: N/A
Technical Abstract: Nitrogen (N) and phosphorus (P) pose a dilemma for agriculture. Although both are required for production of high quality, protein-rich food, purchase and application of these two fertilizer elements are the two most costly inputs for farmers. Their ease of access and overuse in the intensive farming of developed countries have led to significant environmental degradation. In contrast, in the extensive farming systems prevalent in developing countries, the high cost and limited availability of N and P restrict yield and reduce quality. An additional problem is that production of N and P fertilizers depends upon nonrenewable resources and as currently used is not sustainable. Because of their unique capacity for symbiotic biological nitrogen fixation, legumes are critical to N sustainability through providing a low cost, renewable supply of N that is less prone to leaching and volatilization. Now it is becoming quite clear that legumes have a major role to play in P sustainability. They have several mechanisms for solubilizing unavailable P which results in enhanced P acquisition, particularly in low P soils. Incorporation of legumes into inter- and rotational-cropping systems provides a low cost alternative to adding P fertilizer for improved soil fertility.