Abstract: The main aim of this present study is to summarize methods of soil fertility assessment, which have widely been used in the world, and to let everyone know the process and methods of soil fertility assessment. The process is divided into three parts: firstly, to select minimum indexes to compose a database; secondly, to standardize all indexes of database; thirdly, to integrate all indexes into a number indicating soil fertility. On the basis of the previous studies, three types of standardized scoring functions typically used for soil quality assessment can be generated: (1) ‘More is better’, (2) ‘Less is better’, (3) ‘Optimum’. The equation defines a ‘More is better’ scoring curve for positive slope, a ‘Less is better’ curve for negative slope, and an ‘Optimum’ curve in which? a positive curve is reflected at the upper threshold value. The methods of soil fertility assessment generally include three types: (1) MVIK (multiple variable indicator kringing), (2) dynamics method of soil quality, (3) integrated score of soil quality. In fact, merits and shortcomings exist in every method of soil fertility assessment. When local soil fertility is evaluated, the best appropriate method should be selected to be suitable for the local conditions.

Key words: soil quality, soil fertility, soil degradation