A Review of Farmland Soil Health Assessment Methods: Current Status and a Novel Approach

Abstract

Healthy soils are vital for food production as 95% of global food production directly or indirectly depends on soils. To ensure the food security of the burgeoning world population, it is necessary to evaluate soil health (SH) with a potential soil health index (SHI). Although there are several reputable methods for SH assessment at present, the connotations of and evaluation methods for SH are still unclear and such indexes are targeted at specific stakeholders or problems. In this study, we reviewed the fundamental steps in current attempts to develop SHIs, SH assessment methods and proposed a unified SHI based on the priorities of stakeholders. The proposed approach was designed as “three sets of dual index systems”, including the soil function (i), nutrition (j), and output (k) index systems, as well as the current (C) and expected (E) values of the respective index systems. The indicators included in index-i, index-j, and index-k reflect the soil regulatory functions, nutrient status, and quality and quantity of the output, respectively. The E values are used as a reference for the C values, and the health status is obtained, by using the ratio (R) of C to E for the respective index systems and their degree of deviation from “1” (R-1). For any evaluated soil, the farther the number of attributes and their ratios deviate from “1”, the unhealthier it is. This approach can provide a unified and comprehensive SH assessment method by diagnosing the most significant, healthy as well as unhealthy indicators. This method can be applied easily, not only by scholars but also by farmers and land managers.