Contrasting roles of inherent soil characteristics, climate, and management for soil property states and changes – Long-term observations from arable soil monitoring sites in Switzerland

Abstract

Soil properties such as soil organic carbon (SOC), nitrogen (TN), phosphorus (PTP), and bulk density (BD) underpin soil fertility and ecosystem functioning, yet the relative importance of factors controlling their long-term states and short-term changes remains poorly quantified. Here, we analyse 35 years of data from 26 arable soil monitoring sites in Switzerland to (i) quantify temporal trends in soil properties across crop rotation types and sites; (ii) identify management, soil, and climate predictors of soil property states and annual changes; and (iii) assess the contexts in which different modelling frameworks provide suitable insights into soil dynamics. We combined indicator-based management and pedoclimatic data and applied linear mixed-effects and nonlinear modelling approaches. Across sites, SOC, TN, and PTP show no consistent trends, while BD decreases slightly over time. Soil texture and pH explain most of the variation in soil property states, whereas climate and management play a stronger role in explaining their changes. As a key management indicator, soil cover days are positively related to SOC and TN states and changes. Linear models provide robust rankings of dominant predictors, while nonlinear models identify context-dependent thresholds and climatic constraints on management responses. Soil organic carbon and TN show meaningful responsiveness to management over time periods of several years, whereas PTP remains constrained by soil buffering, and BD varies primarily with climatic conditions. Overall, soil management and policy should prioritize the continuity of protective measures and site-adapted management that reduces soil degradation risks and aligns practices with local soil and climate conditions.