ABSTRACT
Carbon and nitrogen are two key elements of global significance, playing large roles in the production of food, feed, fiber, and fuel for human existence, as well as providing numerous other ecosystem services. Although nitrogen is often a limiting element in natural systems, it can become a polluting element as a by-product of agricultural management due to the many pathways for it to be lost from the point of application (high input of nitrogen fertilizers has occurred during the last half century to achieve high production goals). Nitrogen loss from leaching, runoff, volatilization, and denitrification can pollute water and air resources. The conundrum of agriculture is to get enough of nitrogen without releasing it to the environment. Continuous biological cycling of carbon and nitrogen with conservation or ecologically based agricultural approaches can significantly reduce the environmental pollution with nitrogen. Limiting the time that inorganic nitrogen is present in soil will limit its loss, and this can be achieved by limiting soil disturbance, maintaining continuous plant and residue cover on soil, and creating a diversified cropping system to balance ecological stability.
