With Dr Xiaohui Chen as the supervisor, Dr Shashank B. Subramanyam was awarded the prestigious MSCA-Individual Fellowship in the Horizon 2020 package in 2021. He joined our research group from 10th February 2022, and the project ended on 14th January 2024. Dr Subramanyam is now working as a Lecturer in Geotechnical Engineering in the School of Civil Engineering at the University of Leeds.

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Grant number: 101031565

Project duration: 10th February 2022 – 14th January 2024

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About the project

Climatic influences various natural phenomena and affect the overall environmental synergy. Precipitation pattern and temperature are among key phenomena that influence the soils and in turn life. Extended periods of droughts leads to loss of nutrition in soils and increases desertification of land. On the other hand, the increase in temperature (natural or anthropogenic activities) that lead to rise in temperatures in the geoenvironment will lead to unstable ground conditions. This situation is more detrimental in the presence of organic matter/organic soils and has been poorly understood. This study aimed to amend the depleted soil with native soil microorganisms and stimulating them with biowaste. Further, through this study aimed to understand the engineering behaviour of biomodified soils (organic soils) under and role of temperatures (Thermo-Hydro-Mechanical behaviour). This will a major step in this direction as till date the conventional practise has been to understand THM behaviour  of soils without biogenic function. In addition, this study also aimed at developing a mathematical (analytical and computational) framework that can predict the behaviour of organic soils. This project employed native soil bacteria to modify the soil properties with an aim to use biomodification for engineering soil behaviour. It was found that the biomodification impacted the soil behaviour to varying degrees under different conditions. Various aspects that have been considered in the assessment are the shear strength, flow behaviour, water retention and thermal properties of the soils. While of these properties varied significantly with biomodification, a few of them have shown little or no significant changes. Also, in order to simulate the soil-water interactions, this study developed a novel analytical framework based on mixture coupling theory to model water retention and drying processes in soils. Further, through this study, field trials were conducted to assess the impact of organic and synthetic nitrogen sources on the crop quality and soil microbiome diversity. The organic source of nitrogen proved to enhance protein content in wheat. The addition of synthetic nitrogen impacts the microbiome quality of agricultural soils. This is seen in the fungal diversity and relative enrichment of key bacteria associated with the nitrogen cycle.

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The study has led to determination of the impact source of nitrogen on quality of wheat and the soil microbiome. This study has provided an initial assessment of the efficacy of an organic source of nitrogen, various other sources of organic nitrogen need to compared with each other and on different crops to determine the most suitable one for a particular crop. Further studies in this direction will help transforming the agriculture into more organic-based farming with scientific backing. Further, this study provided an initial insight into modifying fine-grained soils with biological methods. While the study aimed to develop modification techniques, the outcomes of this study has also provided an insight into the natural processes that are influencing the soil characteristics and behaviour.