Advancing citrus orchard soil health assessment through an environmental risk screening and multi-dimensional indicator integration framework

Abstract

Soil health is fundamental to agricultural productivity, and its evaluation and key determinants are critical for sustainable agriculture. Citrus is the most widely cultivated fruit crop globally, but there have been limited studies addressing soil health in citrus orchards. Here, we propose an innovative two-step framework for comprehensively evaluating soil health in citrus orchards. First, soils were screened using the single pollution index: samples exceeding the environmental risk threshold were directly classified as unhealthy, whereas compliant soils were further assessed using the Nemero comprehensive pollution index to quantify their envi-ronmental risks. Secondly, environmental risks together with physical, chemical, and biological indicators were assigned with weights determined through the coefficient of variation and analytic hierarchy process combined with membership functions. The weighted indicators were then integrated to calculate the comprehensive soil health index (CSHI), which was used to classify soil health status. Sixty soil samples were collected from citrus orchards in Hubei Province, China. The results showed that 40.0 % of soils were classified as healthy (CSHI ≥0.70), 58.3 % as sub-healthy (0.50 ≤ CSHI < 0.70), and 1.7 % as unhealthy (CSHI <0.50). Soil pH and organic matter were identified as the dominant limiting factors, while micronutrient deficiencies further constrained soil health in certain regions. Importantly, CSHI was positively correlated with both citrus yield (R2 = 0.76) and citrus quality (R2 = 0.57–0.81). The established framework advances soil health assessment in citrus orchards and provides a robust basis for guiding nutrient management and soil regulation.