Soil quality assessment via the factor analysis of karst rocky desertification areas in Hunan, China

Abstract Quantitative evaluation of soil quality (SQ) is of paramount importance to provide a basis for restoring degraded land that affects the living conditions of people in these degraded areas. Amongst land degradation types, karst rocky desertification (KRD) is caused by human disturbance on a fragile karst geo‐ecological environment. However, SQ evaluations have not been widely and correctly used in KRD soil systems due to the complex soil conditions and lack of uniform standards. SQ evaluation can be qualitatively and quantitatively calculated. Soil quality index (SQI) can be used more frequently due to its simplicity and quantitative flexibility. To quantitatively analyse the SQ of four KRD grades in Hunan Province in China, 25 soil properties at 0–20 cm were identified as potential SQ indicators. SQ was assessed via SQI based on a total data set (TDS) and a minimum data set (MDS). Similar to grey relational analysis (GRA), the SQI was ranked as follows: potential KRD>moderate KRD>light KRD>intensive KRD. Total phosphorus, pH, calcium, clay, capillary porosity, biomass nitrogen and microbial biomass phosphorus were selected into the MDS, and they were sensitive to SQ. However, available phosphorus and soil organic carbon were not selected in the MDS. Soil quality in KRD areas could be quantitatively evaluated using SQI via factor analysis. SQ assessment based on the MDS can represent TDS to reduce labour intensity and detection costs. The quantification of SQ under different KRD grades can provide reference for improving SQ in limestone rocky desertification areas.