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QUADRAT DTP: Biogeochemical cycling in paddy soils: Impact of climate-smart water management


   School of Biological Sciences

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  Dr Gareth Norton, Prof Adam Price  No more applications being accepted  Competition Funded PhD Project (Students Worldwide)

About the Project

Background: This project underpins international aspects of sustainable land use. Rice is a dominant human food but also the most water-demanding staple crop globally. This high-water use is due to its cultivation; in flooded field it requires 2-3 times more water than other arable crops. The high dependency of conventional paddy rice production on water makes this cropping system unsustainable in some parts of the world and vulnerable to water shortages. Particularly problematic for the future are regions where aquifers are being over-exploited, where climate change is predicted to negatively impact water balance in agriculture and where there is high competition for water between rice producers and other water-users. Finding means of matching rice production with current and future water availability is a critical challenge for rice-producing nations and requires techniques that reduce water use while not impacting on yield. To address these challenges a number of water saving techniques have been developed to reduce the volume of water required for rice irrigation while maintain rice yields. One of these techniques is alternate wetting and drying (AWD). AWD or similar technologies will be a key process in climate mitigation. During AWD irrigation the rice fields undergo multiple rounds of flooding. Water levels in the soil are then allowed to naturally drain away, to a predefined condition, then the fields are flooded again. Work using this technique has demonstrated that water used for irrigation can be reduced by 20-40% while rice yield can be maintained or even increased. 

AIM: While the impact of AWD on reducing water for irrigation and the effect on yield has been studied, less is known about the impact of AWD on the soil environment.  When soil undergoes changes between flooded and non-flooded conditions the redox potential will alter. Many of the nutrients required by rice plants, present in the soil, will undergo changes in chemical form and therefore changes in availability to the plant. It has been demonstrated that when plants are grown under AWD compared to continuously flooded conditions they accumulated more of some elements and less of others. The goal of this project is to understand where, when and how nutrient availability is altered in the soil under AWD and in doing so explore the potential of an optimised AWD system for nutrient availability to rice plants. In addition to water management, a range of soil amendments, commonly used in Bangladesh, (e.g. organic matter) will be used in conjunction to AWD, to assess the impact these have on nutrient cycling in the soil.   

 

RESEARCH METHODS & SKILLS TRAINING: This project will use a range of cutting-edge techniques to determine nutrient availability in soils when managed under water saving conditions. Techniques include; diffusive gradients in thin films (DGT) multilayer chemical-imaging, which provides a high-lateral resolution (sub-mm), two dimensional mapping of in situ porewater solute fluxes; cryo-micro sampling of soil structure; frequency quintupled 213 nm Q-switched Nd:YAG laser ablation-ICPMS; and DIFS (DGT Induced Fluxes in Sediments) model for parametrising solid-solute kinetics and equilibrium resupply. DGT substrates employing novel functionalised mesoporous silicon nanomaterials will provide As/elemental speciation selectivity providing new geochemical insight into the soil transformation during AWD. 

Candidate Background: The successful candidate should have knowledge of soil biology and a background in biogeochemistry or analytical chemistry. A background knowledge/experience in plant biology is desirable.

More project details are available here: https://www.quadrat.ac.uk/quadrat-projects/

How to apply: https://www.quadrat.ac.uk/how-to-apply/ 


Funding Notes

QUADRAT studentships are open to UK and overseas candidates. Funding covers:
• A monthly stipend for accommodation and living costs, based on UKRI rates (currently £17,668 pa for 2022/23, updated annually)
• Fees (home rate tuition fees and/or fee waiver for overseas fees, where applicable)
• Research and training costs
For further information before applying please check full funding and eligibility information: https://www.quadrat.ac.uk/funding-and-eligibility/

References

1. Norton, GJ, Travis, AJ, Danku, JMC, Salt, DE, Hossain, M, Islam, MR & Price, AH 2017, 'Biomass and elemental concentrations of 22 rice cultivars grown under alternate wetting and drying conditions at three field sites in Bangladesh', Food and Energy Security, vol. 6, no. 3, pp. 98-112.
2. Norton, GJ, Shafaei, M, Travis, AJ, Deacon, CM, Danku, J, Pond, D, Cochrane, N, Lockhart, K, Salt, D, Zhang, H, Dodd, IC, Hossain, M, Islam, MR & Price, AH 2017, 'Impact of alternate wetting and drying on rice physiology, grain production, and grain quality', Field Crops Research, vol. 205, pp. 1-13.
3. Yin, DX, Fang, W, Guan, DX, Williams PN, Moreno-Jimenez, E, Gao, Y, Zhao, FJ, Ma, LQ, Zhang, H, Luo, J 2020. Localized Intensification of Arsenic Release within the Emergent Rice Rhizosphere. Environ. Sci. Technol. vol. 54, pp. 3138–3147.
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