Rooting for sustainable performance

Lead Research Organisation: University of Aberdeen
Department Name: Inst of Biological and Environmental Sci

Abstract

More frequent intense rainfall events, associated with climate change, increase the likelihood of shallow slope failures that lead to costly disruption of road and rail journeys, with risk to life and property. There have been recent slope failures adjacent to transport corridors in the UK, sometimes disrupting important road and rail routes for days. Vegetation has a stabilising effect on slopes: Plant root systems interlock with the soil, increasing its stiffness and strength. Uptake of water by root systems dries the soil profile, again increasing soil stiffness and strength. However, engineers need to be able to predict the combined root reinforcement and soil drying effects on slope stability, so that vegetation management can be used proactively to decrease the probability of slope failure. Vegetation has numerous benefits over conventional hard-engineering solutions, in terms of burying carbon in the soil, enhancing biodiversity, and improving the aesthetic quality of the environment for society.

This project will develop and test a quantitative coupled hydro-mechanical model for the in-service and ultimate-failure performance of slopes planted with vegetation. Rooted-soil represents an innovative sustainable construction material, with distinct mechanical and hydrological properties, that can be used in geotechnical systems. The model will be applicable to both slopes covered with natural vegetation and slopes where vegetation and soil have been chosen and managed according to engineering principles. The validated model will provide a clear framework for assessment and remediation of slopes with potential for reducing economic and carbon costs.

The model will be developed within a multi-scale continuum modelling framework. It will build on knowledge of the elemental components of the system, working from individual soil-root interaction, to continuum soil-root system, and to complete slope, incorporating spatial variability of materials. Modelling will be informed by X-ray CT imaging of the 3-D deformation of rooted soil undergoing shear, using the micro-VIS facility at the University of Southampton, and by field data from slopes containing established vegetation. Predictions of slope performance will be validated against scaled-slopes in the Dundee geotechnical centrifuge under different rainfall regimes. The geotechnical centrifuge enables the testing and monitoring of small-scale slopes containing roots at realistic stresses, which can be manipulated until the slopes ultimately fail.

Template guidelines will be produced for a manual of combinations of plant species, soils and management schemes for optimum performance of designed soil-plant systems suited to emerging climatic conditions. Example data will also be included to allow cost-benefit analyses when designing for slope improvement using vegetation. The potential to translate research findings into related areas will be investigated (e.g. river banks, sand dunes, flood embankments, agricultural and amenity systems). We will engage with an important group of Project Partners, representing key industrial sectors and infrastructure owners, to facilitate the rapid adoption of research findings.
 
Description Most of these findings will be reported in the Lead PI submission from Prof Glyn Bengough. We have complemented this work by exploring how root-soil interface properties influence pull-out behaviour by plant roots, and other research exploring how plant roots change soil physical structure over time. I was co-author on a paper by Dr Liang on using printed 3D structures to mimic plant roots for scaling experiments in a geotechnical centrifuge. With Dr Chaobo Zhang we explored how drying of roots affected mechanical behaviour, identifying a large source of environmental variability that may affect slope stabilisation.
Exploitation Route There are several PDRAs working together at the moment.
Sectors Construction,Environment,Transport

 
Description Industry panel benefitting from new research on use of vegetation to stabilise slopes. Direct involvement in annual meeting. Please see the more detailed entry from Prof Glyn Bengough who is the lead PI on this project.
First Year Of Impact 2016
Sector Construction,Environment,Transport
Impact Types Economic

 
Description UK Parliament - Environmental Audit Committee, Soil Health Enquiry
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description Diamond Light Synchrotron Session
Amount £700 (GBP)
Funding ID MT12525 (Hallett) Visualising the movement of plant roots and the impact on soils 
Organisation Diamond Light Source 
Sector Academic/University
Country United Kingdom
Start 05/2016 
End 11/2016
 
Description CREW Soil Structure and Drainage Study 
Organisation James Hutton Institute
Country United Kingdom 
Sector Public 
PI Contribution This is broad scale project examining soil structure across Scottish agricultural fields. It provides information on the state of soils and constraints that may be experienced by plant roots. The surface degradation of the soils is relevant to understanding ecoengineering options as per the EPSRC project.
Collaborator Contribution Paul Hallett is PI on this CREW project. The data will be used to inform the NERC CZO, BBSRC SARISA and EPSRC Slopes projects.
Impact This work will be used to train catchment managers in identifying soil structure and drainage problems on farms. The data will also inform public policy on soil degradation and flood impacts during winter months. Given the very wet 2015/2016 winter that resulted in widespread flooding, the results are very relevant to environmental sustainability.
Start Year 2014
 
Description China Scholarship Council - Visiting Researcher - Dr Chaobo Zhang 
Organisation Taiyuan University of Technology
Country China 
Sector Academic/University 
PI Contribution 1 year visit to the University of Aberdeen. Research is exploring the mechanical reinforcement of soils by plant roots, focussing on the impact of mucilage on root-soil interface properties and pull-out mechanics. Work bridges ongoing research in BBSRC Rhizosphere by Design project and EPSRC Rooting for Sustainable Performance. We are providing mechanical testing equipment and discussing experimental approaches. Treatments are informed from our RCUK research.
Collaborator Contribution Dr Zhang conducts research on vegetation reinforcement of slopes in China.
Impact We anticipate two publications from this work.
Start Year 2016
 
Description Collaboration - Hydrophobic soils for slope stabilisation 
Organisation University of Hong Kong
Department Department of Civil Engineering
Country Hong Kong 
Sector Academic/University 
PI Contribution Dr Sergio Lourenco is the project lead. Work is being conducted in Hong Kong. We provide support in soil physics, biology and root-soil interactions. 2016-2019 General Research Fund (HK Research Grants Council), Durable synthetic water repellent soils for sustainable ground infrastructure, PI Lourenço, Co-I's: Dr Johnny Cheuk (AECOM HK), Prof Paul Hallett & Prof Graeme Paton (Aberdeen University), Dr Albert Yeung (HKU), HKD676k
Collaborator Contribution Dr Sergio Lourenco is the project lead. Work is being conducted in Hong Kong. We provide support in soil physics, biology and root-soil interactions. A team of scientists and engineers with expertise in soil mechanics, soil science and microbiology, consisting of Dr Sérgio Lourenço (SL), Prof. Paul Hallett (PH), Prof. Graeme Paton (GP) and Dr Johnny Cheuk (JC), will implement this research. The first step in the development of durable synthetic water repellency is to identify time-stable water repellent treatments. Three approaches will be examined: impregnating an initially wettable soil with organic coatings such as dissolved organic carbon; changing the surface chemistry with silanes; and enhancing water repellency by altering soil particle attributes (shape and size). In the second step, the spatial and temporal evolution of the treated soils will be tracked by monitoring their response to forced degradation and to microbiology and vegetation scenarios similar to those they would be exposed to in the field. This will identify the limit conditions under which water repellency will revert to its original (wettable) state and the controlling underlying processes such as deposition of wettable particles, growth of microbial biomass and physico-chemical transformations. This research will provide Hong Kong with a novel technology for constructing water-tight barriers and fills that is both inexpensive and reliant on an abundant local resource - soils. Our research will verify its stability, so that perceived risks to practical implementation are identified and alleviated.
Impact Multidisciplinary: geotechnical engineering, toxicology, soil science, eco engineering
Start Year 2017
 
Description Lin Hongjie, PhD student placement 
Organisation University of Hong Kong
Department Department of Civil Engineering
Country Hong Kong 
Sector Academic/University 
PI Contribution Hongjie Lie spent one month at the University of Aberdeen exploring a new slope stabilisation technology that made soil hydrophobic by adding amendments. We taught him ecotoxicity assessments (joint with Prof Graeme Paton) and also methods to measure hydrophobicity in soil. He was integrated into 2 research groups in Aberdeen to expose him to the research of different labs. He provided a talk and we discussed his research project.
Collaborator Contribution We collaborate with the University of Hong Kong on developing technologies to improve slope stability by making soils hydrophobic. This work is led by Dr Sergio Lourenco in the The University of Hong Kong, Department of Civil Engineering. They provided all the samples used in this exchange. Prof Paton and I serve as collaborative scientists on this work.
Impact Multidisciplinary: Civil engineering, soil biology, soil physics, root:soil interactions.
Start Year 2017
 
Description NERC El Nino BREAD 
Organisation Hawassa University
Country Ethiopia 
Sector Academic/University 
PI Contribution This is a NERC El Nino project where we are exploring the impact of organic resource amendment and cropping practice on soil properties. The work from the EPSRC project provides fundamental information to help with understanding how plants contribute to soil stabilisation under hydrological stress (drought and flash floods), as well as allow the soil to absorb more rainfall.
Collaborator Contribution My group leads the research on soil biophysical measurements to be used in ecosystem modelling. A group from the Southern Agricultural Research Institute are performing measurements on the ground.
Impact Stakeholder workshops in Ethiopia. Presentations to NERC. A special issue of a journal is underway.
Start Year 2018
 
Description NERC El Nino BREAD 
Organisation James Hutton Institute
Department Social, Economic and Geographical Sciences
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution This is a NERC El Nino project where we are exploring the impact of organic resource amendment and cropping practice on soil properties. The work from the EPSRC project provides fundamental information to help with understanding how plants contribute to soil stabilisation under hydrological stress (drought and flash floods), as well as allow the soil to absorb more rainfall.
Collaborator Contribution My group leads the research on soil biophysical measurements to be used in ecosystem modelling. A group from the Southern Agricultural Research Institute are performing measurements on the ground.
Impact Stakeholder workshops in Ethiopia. Presentations to NERC. A special issue of a journal is underway.
Start Year 2018
 
Description NERC El Nino BREAD 
Organisation Southern Agricultural Research Institute (SARI)
Country Ethiopia 
Sector Charity/Non Profit 
PI Contribution This is a NERC El Nino project where we are exploring the impact of organic resource amendment and cropping practice on soil properties. The work from the EPSRC project provides fundamental information to help with understanding how plants contribute to soil stabilisation under hydrological stress (drought and flash floods), as well as allow the soil to absorb more rainfall.
Collaborator Contribution My group leads the research on soil biophysical measurements to be used in ecosystem modelling. A group from the Southern Agricultural Research Institute are performing measurements on the ground.
Impact Stakeholder workshops in Ethiopia. Presentations to NERC. A special issue of a journal is underway.
Start Year 2018
 
Description PhD Student - Post-tillage soil structural evolution and pore space dynamics 
Organisation Swedish University of Agricultural Sciences
Country Sweden 
Sector Academic/University 
PI Contribution Co-supervisor of PhD student - "Post-tillage soil structural evolution and pore space dynamics" Expertise on soil mechanics and structure dynamics.
Collaborator Contribution Prof. Thomas Keller is the lead supervisor of this project.
Impact Student training. Multidisciplinary between soil physics, imaging and agronomy.
Start Year 2017
 
Description EGU2017- Make the rhizosphere great again: microbes build walls in soil that roots pay for by Paul Hallett et al. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact PICO presentation in session SSS4.16 - Unravelling soil-biota interactions using micro-scale analyses:
Year(s) Of Engagement Activity 2017
 
Description International Society of Root Research Medal Lecture 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The ISRR2017 medal lecture invites an eminent scientist who explores root-soil interactions to Dundee to present a lecture, preceded by talks and poster sessions by predominantly early career researchers. This year the invited speaker was Prof Michelle Watt from Juelich.
Year(s) Of Engagement Activity 2017
URL http://www.hutton.ac.uk/events/root-rhizosphere-workshop-and-2017-isrr-dundee-medal-lecture-root-res...
 
Description Invited seminar to ETH Zurich 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Prof Paul Hallett provided a talk on how soil structure interacts with plants. This drew on both agronomic and engineering applications.
Year(s) Of Engagement Activity 2015
 
Description NERC Planet Earth Article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Article in the NERC Planet Earth magazine, written by journalist Julia Horton. This covered a range of projects conducted by University of Aberdeen scientists on tropical agriculture. The work draws on both our direct research in tropical countries and strategic research on plant-soil interactions, so it cuts across P. Hallett's funding portfolio.
Year(s) Of Engagement Activity 2017
URL http://www.nerc.ac.uk/planetearth/stories/1879/
 
Description NERC UnEarthed 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact NERC UnEarthed was a large event that attracted over 3000 people. There were two days dedicated to school visits and 2 days when there was free entry to the general public. During our free interactive showcase - UnEarthed - at Dynamic Earth, Edinburgh (17-19 November), families and adults could explore the tools used to make science happen and see the extraordinary work of our scientists. Our exhibit focussed on a range of research projects in tropical ecosystems, specifically on the impacts of agriculture and strategies that could be taken to minimize environmental impacts. The text we used to attract visitors was: Emerging from a Scottish forest you stumble across an orangutan in her nest, with drone footage of her natural habitat. What can this have to do with Scotland? Your food choices affect her habitat, other tropical regions, and the livelihoods of local people. A grocery basket will show you how much of what you eat is tropical. Guess the water used and greenhouse gases emitted producing this food, and then measure it yourself with a gas meter and carbon calculator.

Our research is finding solutions to make this food more sustainable and to protect the livelihoods of people living in vulnerable tropical regions. The most important tropical food is rice. You will see how rice can be selected to grow better with less water by reaching deeper soil with its roots. The other major solution is improving tropical soils. By adding carbon, we will show how they can be restored. Our man dressed as an orangutan was a highlight with kids.
Year(s) Of Engagement Activity 2017
URL http://www.nerc.ac.uk/latest/events/archive/unearthed/