A regional comprehensive soil quality evaluation method for orchard green agricultural development: Integrating soil fertility and environmental indicators in Hainan, China

Effective soil quality evaluation can improve soil health and productivity as well as promote sustainable agricultural development. In this paper, a regional comprehensive soil quality evaluation method provides powerful tools for simultaneous assessment of the soil environment and soil fertility qualities based on an improved version of TOPSIS (Technique for Order Preference by Similarity to Ideal Solution, a mathematical calculation of multi-criteria decision analysis) combined with a fuzzy mathematical model. Eleven soil fertility and soil environment quality indices were selected to establish an index system for green agricultural development at the orchards in Hainan—a typical tropical fruit production area in southern China. Results showed that the soil fertility was primarily limited by three controlling factors: low total nitrogen (TN) content, low organic matter (OM) content, and acidic pH, indicating that these soils in the study area might experience poor nutrient and acidification problems. Besides, the soils were subject to minor pollution from heavy metals, with Chromium (Cr) and Lead (Pb) being the the main contaminants affecting the soil environment quality. The soil quality index (SQI) exhibited a highly significant positive correlation with the soil fertility quality index (SFQI), suggesting that soil fertility is a crucial factor influencing soil quality. The average SQI value is 0.60 (ranging from 0.40 to 0.85), within the high grade, indicating an overall good soil quality in Hainan orchards. These findings provide a reference for classifying and defining soil quality, and understanding the current state of soil quality in Hainan orchards . • We conducted a comprehensive soil quality evaluation of the orchards in Hainan. • A soil evaluation model based on soil heavy metals and nutrients was established. • Overall, the soil in the study area is not very fertile. • N content, organic matter content, and acidic pH limit soil fertility. • Soil quality is primarily limited by the soil fertility level.