Estimating the contribution of root exudation to C storage in temperate agricultural soil
The project aimed to give the student an experience of working in the environmental and soil science sector to highlight the dynamic and complex nature of carbon research, and the importance of this type of research in the context of increasingly significant environmental issues including global warming and climate change.
The project aimed to use the resources available at Bangor University Environment Centre Wales and at the Bangor University research station (Henfaes). This intended to show an undergraduate student how a research project is carried out from start to finish on a small scale. This included teaching the student new skills, how they are applied and how to effectively manage and use available resources when carrying out a research project.
The specific experiment was designed to quantify root exudation of four week old ryegrass (Lolium perenne) in the lab in the presence and absence of microorganisms through 14C labeling. This was designed to discern the rate and contribution of root exudation to carbon storage in a temperate agricultural soil. A sterile and inoculated sand culture was used to gain better insight into the complex carbon dynamics. The project specifically focused on the effect of mycorrhizal fungi including: the effect on plant respiration, root growth and development and root exudation over specific time intervals. This was placed in the context of the whole plant- root continuum to effectively estimate the carbon allocation in plant roots, shoot and root exudates in ryegrass.
Benefits to the student included learning the theoretical background to the complex nature of belowground interactions in terrestrial ecosystems. The student was able to use Bangor University resources to search and process literature surrounding the subject area. The student experienced how research is carried out and the working of a biology lab including a range of techniques, day-to-day running and the software used to interpret results of experimental studies. A range of microbiological techniques including sterilization, aseptic techniques, inoculation and incubation were used to grow and maintain plants in sterile and non-sterile culture conditions. The student was able to discern and create mesocosms of different treatments and learnt the different factors and variables to be considered when designing an experiment. The student also experienced working under field conditions, learning a range of techniques including site selection criteria, and soil sampling methods. This included learning the procedure of sampling, processing and storing soil from the field to the lab using a variety of equipment. The student received radiation safety training and was able to effectively pulse label plants safely under supervision. Training included the health and safety risks and hazards associated with radiation (specifically 14C), how radioactive isotopes are dispensed, used and disposed of in the lab according to legislation. Data collection and analysis was carried out by the student. This enabled to student to effectively manage datasets, and use software packages such as Microsoft Excel and R studio to collate data.
Response of mountain soils to extreme events
1. To explore the impacts of simulated extreme precipitation events on mountain soil respiration
2. To identify tipping points in functions
3. To test a methodology for simulation of extreme rain events
4. To expose the candidate to field and laboratory methods used in ecology
5. To train the candidate on design of experiments
6. To demonstrate the general working ethics and practice in terrestrial ecology
The student gained a valuable experience of exposure to field work in the Cairngorms and the Lake district fells. This included visiting and sampling from a long-term research site, and the logistics of sampling in a highly heterogeneous environment. The student participated in the process of design, sampling and measurement of various ecological parameters. The research outputs allowed evaluation of the methods of simulating extreme rainfall events in the lab, and identified some impacts on soil respiration. The project helped proof of concepts, and refined methodological approaches as part of a larger project. In the second strand, the student aided processing soils from a long-term experiment. These data will yield a publication, in which the student will gain recognition.
The student benefitted mainly in terms of insight into the workings of a research group, and the means by which questions are posed and followed through in a hypothesis-driven methodology.
Quantifying Soil Health and Quality
i. To investigate determinants of soil health and quality
ii. To build a Bayesian Belief Network that connects the most important components identified in iii. in a logical fashion to explain differences between soils
iii. To populate the network with data and produce preliminary inferences of how soil health and quality are related, quantifiably, with soil properties and land-use
The project aimed to develop a preliminary understanding of the use of latent variables in Bayesian Belief Networks to infer soil quality.
The student has received a general understanding of the importance of good quality soils to the agriculture and the natural environment and in particular the factors that underlie soil quality. He has explored the use and structure of BBNs and is now competent at constructing nets and interfacing nets with case data in order to derive conditional probability tables to make inferences.
He has explored the use of several sets of data, including data from the revision of the fertilizer guidance for Defra and the long-term Broadbalk wheat experiment at Rothamsted in order to infer soil quality as a latent variable from functional relationships in the data. He has looked closely at the inferences and explored odd results in a sensible fashion.
The student wrote a final report which documents the various approaches that he explored and gives useful detail on how these were implemented within the Netica software package. He also gave a short departmental seminar providing the audience with a lively and accessible overview of the work he had carried out.