**1. Introduction**

Composting is an inexpensive, efficient, and sustainable treatment for solid wastes. In China, the composting industry has been growing rapidly, owing to a boom in the animal industry over the past decades. Because an immature compost applied to soil results in seed germina‐ tion inhibition, root destruction, and a decrease in the O2 concentration and redox potential [1, 2],assessingorganicfertilizermaturityiscritical.Bytheway,amaindifferencebetweencommon composts and commercial organic fertilizers is the complexity and unpredictability of the raw materials of the latter.

In recent decades, livestock numbers have increased dramatically in China. The quantity of manure generated by China's livestock has increased significantly as a result of the rapid increases in livestock numbers. The quantity increased by at least fourfold between 1980 and 2005, to an annual estimated total of 3060 million tons (Mt, fresh weight of manure) in 2005. [3] It was estimated that manure generation in 2010 was ca. 2800 Mt (fresh weight). [3] In addition, organic fertilizer amendment has been shown to be an effective way of increasing soil organic matter (SOM) content and reducing environmental pollution. However, the mechanism of storage of SOM remains largely unknown. Recently, some investigators have shown that organic fertilizer amendments could enhance the production of highly reactive short-range ordered (SRO) minerals, which further benefit for SOM storage and soil fertility improvement. [4–6]

In this chapter, compost process and status, novel spectroscopy techniques in assessing compost maturity, and improvement of soil fertility by organic fertilizer amendments in China are introduced.
