Centennial Fertilization-Induced Soil Processes Control Trace Metal Dynamics. Lessons from a Long-Term Bare Fallow Experiment

Folkert Van Oort,Remigio Paradelo,Ghislaine Delarue,Fabrice Monna,Denis Baize,Nicolas Proix

doi:10.3390/soilsystems2020023

Abstract

Long-term bare fallow (LTBF) experiments with historical sample archives offer unique opportunities to study long-term impacts of anthropogenic activities on mineral soil fractions. In natural agro- and ecosystems, such impacts are often masked by organic matter due to its buffering action and rapid turnover. The 42-plot LTBF trial of INRA (Institut National de la Recherche Agronomique) started in Versailles (France) in 1928 to assess the impacts of prolonged application of fertilizers and amendments on the composition and properties of loamy soils. Here, we established geochemical budgets of major and trace elements on surface samples from 1929 and 2014 for four groups of treatments relevant for developed soil processes. We considered accompanying effects of soil compaction or decompaction due to changing physicochemical conditions over 85 years. Element losses from the surface horizon were quantified via fertilization-induced or -amplified soil processes: clay leaching favored by Na- or K-based fertilization, and lixiviation of major and trace elements in acidic or alkaline soil conditions. Enhanced mineral weathering was shown for acidified and nonamended plots. Conclusions on trace metal migration were confirmed by selected analyses on subsurface horizons. Additional information was provided on specific element inputs via fertilizers and/or diffuse inputs via atmospheric deposition.

Highlights

Soil degradation or, better, degradation of soil properties may result from both anthropogenic activities and natural processes, i.e., land misuse, soil mismanagement, or climatic change and related factors [1]
The relevance of our computational approach was checked by the equivalent losses of scandium and clay in Na-based fertilized plots, under the hypothesis of a predominant location of Sc in phyllosilicate minerals in loess soil
The budgets gave insight into a series of diverging element losses controlled by different soil processes that were induced by changing physicochemical soil conditions over 85 years, which can be considered as a long-term time span in agronomic experimentation studies, but rather a short-term time span in soil development

Summary

Introduction

Better, degradation of soil properties may result from both anthropogenic activities and natural processes, i.e., land misuse, soil mismanagement, or climatic change and related factors [1]. Pools occupy a central place in problematic global change, with respect to reduced biodiversity, decreased aggregate stability and soil compaction, and nutrient loss [1,2]. 2018, 2, 23 most reliable indicator for monitoring soil degradation [4], by soil erosion. This reputation is due, in large part, to short-term response on climatic or anthropogenic constraints and rapid turnover dynamics in soils [5,6]. Changing land use and management or agricultural practices may affect the soil’s mineral fraction, in particular the finest reactive phases

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