Evaluation of indirect and direct scoring methods to relate biochemical soil quality indicators to ecosystem services

Abstract

Soil health assessments use scoring curves to quantify relationships between soil quality indicators (SQIs) and ecosystem services (ESSs). We evaluated methods for scoring curve development using three labile C pools (β-glucosidase [BG], fluorescein diacetate [FDA] hydrolysis, and permanganate oxidizable carbon [POXC]). Concepts and methods for SQI interpretation used by established frameworks were assessed, with 129 studies reporting relationships to either soil organic C (SOC) (n = 367), a common surrogate for indirect estimation of ESSs, or direct measures of crop yield (n = 88), soil respiration (n = 66), and N2O and CH4 emissions (n = 51). Indirect assessment of BG using SOC and site covariates resolved tillage-based differences (P