Project Description
Background
This project underpins international aspects of sustainable landuse. 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.
This project will be a predominantly laboratory and greenhouse-based study, but with the potential to conduct the soils sampling in Bangladesh. Soils will be collected from paddy fields in Bangladesh and will reflect the major pedological classes used in rice cultivation.
This project will be in collaboration with:
- The Soil Resource Devolvement Institute, Bangladesh; a government/statutory organization that carries out research on soil and surveys on soil quality to improve agriculture in Bangladesh.
- Bangladesh Agricultural University (BAU), the country’s premier agriculture research University
Essential & desirable candidate skills
Essential: For this project we are looking for an enthusiastic candidate with a knowledge of soil biology and a background in biogeochemistry or analytical chemistry.
Desirable: It is desirable that the candidate has background knowledge and experience in plant biology.
Supervisors
Gareth NortonPrimary Supervisor: | Profile: Gareth Norton Email: g.norton@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Biological Sciences |
Paul N. WilliamsSecondary Supervisor: | Profile: Paul N. Williams Email: p.williams@qub.ac.uk Institution: Queen's University, Belfast Department/School: School of Biological Sciences |
Adam PriceAdditional Supervisor: | Profile: Adam Price Email: a.price@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Biological Sciences |
References
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.
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.
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.
Research Methods
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.
Impact
Water use for irrigation at its current rate is not sustainable in Bangladesh, and Bangladesh is not the only country to have this issue. Within Asia, it is estimated 50% of all fresh water is being used for rice irrigation. With global rice production needing to increase by 70% by 2030, demands on fresh water for irrigation of rice will only increase unless water management techniques that reduce water use are developed and implemented.
A number of technologies have been developed to reduce the input of water for rice irrigation, including AWD, but little work has been conducted on the impact that these techniques have on nutrient dynamics in the soil, and the interplay of AWD across different soil types and therefore availability for plant uptake. It is important that alterations in field management do not have a negative impact on nutrient uptake by plants or if there are issues/problems that negatively impact the long-term sustainability of AWD that can be circumvented with the correct soil amendment/fertiliser management.
Assessing the impact that water management, with and without soil amendments, has on nutrient dynamics in the soil will allow water management systems to be optimised not only for water use but also for nutrient uptake by plants. It will also allow the development of targeted fertiliser application.
Ultimately, the combination of optimised water management and fertiliser applications will contribute to food security while reducing the amount of water used for rice cultivation. Although, this project is focused on Bangladesh, the findings have broad translatability to all rice production regions globally.
Proposed Timetable
The project will be split into 5 stages. Stage 1 and 2 will be completed by project month 6. Stage 3 will be completed by project month 15. Stages 4 and 5 will start at project month 15
- The initial stage will be the optimisation of a reproducible greenhouse system that replicates AWD at the field level. Work in Aberdeen over the last five years has developed several systems at a range of scales which can be modified to meet the needs of this project.
- Identification and sampling of key agronomically important soils from Bangladesh. Bangladesh has a wide variation in soils, and can be split into a number of agroecological zones. These soils will then be sampled in collaboration with SRDI and BAU.
- Technique development. Initial experiments will use a range of techniques to determine the impact that water management has on nutrient release from the Bangladeshi soils. Techniques will be compared and a suite of analysis tools developed.
- Development of an optimised water management system in conjunction with soil amendments. This will involve a range of different experiments looking at how different amendments effect nutrient availability and how they interact with water management and impact on nutrient dynamics.
- Development of an in silico decision support tool parameterised from the data from stage 4.
QUADRAT Themes
- environmental-management
Partners
Not applicable at this time.
