Table 1. Summary of soil quality assessment methods.

Soil assessment methods	Research areas	Indicator	Summarization
Celik et al. (2021)	Soil quality of long-term conservation and conventional tillage practices used in wheat-corn-soybean rotation	Available phosphorus and potassium concentrations, plant available water capacity, penetration resistance, potentially mineralizable nitrogen, microbial biomass carbon, and soil pH	Combining various soil properties into an integrated index can assess soil quality better than individual indicators. No single method can be applied to all soil quality assessments due to the inherent differences between soils. The comprehensive evaluation of soil quality in a specific region must be carried out on the premise of fully understanding the regional soil characteristics
Yang et al. (2021)	Soil quality of various Tamarix chinensis-grass patterns on coastal soil quality	Electrical conductivity, pH value, main cation ions contents, and available nutrients
Yang et al. (2023)	Soil structure of cultivated land	Carbon source indicators
Yu et al. (2017)	Soil quality under different land use patterns in northern China	Soluble organic carbon, active organic carbon, invertase, and the N/P ratio
Raiesi (2017)	Soil quality degradation after converting to cultivated land in arid and semi-arid upland surroundings	Soil organic carbon, electrical conductivity, and arylsulfatase
Wang et al. (2023b)	Soil quality evaluation of grassland in the Qinghai–Tibet Plateau	Soil water content, soil bulk density, capillary porosity, non–capillary porosity, soil organic matter, total nitrogen content, total phosphorus content, total potassium content, alkali–hydrolyzable nitrogen
Zhang et al. (2022)	Soil quality under various composting treatments	The ‘S’ type membership function