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A conceptual framework to study soil aggregate dynamics

Abstract:

The objective of this study was to develop a conceptual framework to study soil aggregate dynamics through the integration of aggregation, disruption, stabilization and destabilization processes of soil constituent units. We used aggregate-size distribution and water stability of macroaggregates to evaluate changes in soil aggregates in two ecosystems where one is the ‘reference’ state and the other is the ‘new’ state. The framework was validated with data from (a) a non-buffered annual row crop (ARC) system, (b) a no-till (NT) system and (c) a bare fallow (BF) system. The dynamics of soil aggregates in the ARC were dominated by the disruption of aggregates (the aggregation–disruption index (ADI) was −0.08), in NT they were dominated by the aggregation process (ADI = 0.03) and in BF dominated by the disruption of aggregates (ADI = −0.20). Three pathways were observed: (a) expression of the aggregation process, which is essential in reestablishing soil structure and functionality, (b) expression of the disruption process, which is critical in the destruction of soil structure and (c) prevalence of mixed behaviour, where the dominant process depended on the relative rate of aggregation and disruption. The proposed framework and study of the carbon associated with aggregates could pave the way for the development of a methodology for the quantitative study of soil organic carbon (SOC) dynamics, carbon inputs (outputs), soil carbon fractions, and edaphic and biotic conditions that regulate SOC dynamics. Highlights: Soil aggregate dynamics were assessed within multiple management systems. A new methodology is proposed for the quantitative study of soil aggregate dynamics. Provided an understanding of aggregation, disruption, stabilization and destabilization in aggregate dynamics. Aggregate dynamic pathways of value in land management can minimize deterioration of the environment.