Nitrogen processes

Nitrogen is unique among the essential nutrients of higher plants in terms of its roles in biological systems and its complex cycling. In addition, it is the element most commonly limiting to crop production and the one most demanding of management skills. Soil organic matter has a pivotal role in cycling nitrogen contents of crop residues and animal manures to the mineral forms that are used by higher plants. In Chapter 7, we found that the level of organic matter reflects the relative rates of carbon and nitrogen inputs and decomposition on the one hand and mineralization on the other. This chapter is concerned with several microbiological and physical processes important in nitrogen cycling and management of nitrogen in agriculture.