How Important is the Quality of Organic Amendments in Relation to Mineral N Availability in Soils?

Wastes generated from municipal and agricultural activities have the tremendous potential for application in agriculture as a source of nutrients and as amendments to improve soil organic matter (SOM). A decline in SOM can represent a serious threat to soil fertility and quality. Nitrogen (N) mineralization from organic amendments is important for understanding the N dynamics in terrestrial ecosystems. In this review, quality of the amendments such as C/N ration, N content, and biochemical compositions, etc. are discussed. Since, C/N ratio cannot explain all differences in N mineralization; emphasis has been laid on characterizing different compounds in organic amendments that govern the mineralization process. The importance of simulation models has also been described in modeling N mineralization from some complex materials like compost, animal manures and farmyard manures. These complex simulation models once modified according to the quality of the organic amendments can simulate N mineralization and thus, they can be used for simulating N dynamics in terrestrial eco-systems.