The two-way interactions between soil organic carbon and soil structure

Well-developed soil structure (i.e. the spatial arrangement of solids and pores) is critical for sustainable crop production. Soil structure is largely influenced by aggregation induced by the microbial decomposition of organic matter.

In turn, soil structure affects soil organic matter (SOM) turnover because pore networks determine microbial access to SOM and the oxygen supply to soil microbes.

These two-way interactions between soil organic carbon (SOC) and soil structure have recently been included in SOC turnover models.

Suchmodels are important tools to analyse the effects of soil and crop management practices and climate change on SOC stocks.

However, it is not clear what determines the amount of aggregation created by SOC and how efficiently this aggregation protects SOM from degradation.To establish relations between SOC, soil structure formation and SOC protection for Swedish soils and climate we will quantify soil structure using X-ray tomography and measure SOC contents and respiration on intact soil aggregates sampled from long-term field experiments.

We will also quantify the formation of soil structure during incubation experiments using sieved soil, organic amendments and reactive aluminium phases.

The results from this project will provide new guidance on model parameterisation and facilitate more climate-smart agricultural management where investments to enhance carbon sequestration are directed to the soils where they will be most efficient.