Workstreams

The REMET-Rice Project adopts a multidisciplinary approach that integrates experimental research, process-based simulation modeling, and applied agricultural practices to mitigate methane emissions and promote climate-resilient rice production. The project is organized into four interconnected workstreams, each addressing a critical aspect of methane reduction and sustainable farming. 

By interlinking these workstreams, the REMET-Rice Project aims to generate practical, evidence-based solutions for reducing methane emissions in rice production. The findings will contribute to the development of climate-smart agricultural practices that enhance sustainability, improve productivity, and support global climate change mitigation and adaptation efforts.

Workstream 1 represents the foundational research phase of the REMET project, focusing on developing innovative methane inhibitors. This includes exploring novel compounds, potentially involving plant-regulatory substances, cable bacteria, and other soil-microbiome interventions such as plant genes. 

These experimental investigations will primarily take place in controlled environments such as incubators, greenhouses, and climate-controlled chambers. These experiments will assess the impact of various nutrients (N, P, K, S) and soil amendments (like cable bacteria and biochar) on both root-associated and soil microbiomes, with specific emphasis on methanotrophs and methanogenic bacterial communities. Results from these studies will also inform and complement field experiments conducted in Workstream 2.

Team Leader: Ando Radanielson

Amendment study in glasshouse using different rates of biochar application

This experiment aimed to evaluate the impact of application of soil amendments on greenhouse gas (GHG) emissions, soil processes, and crop performance under two water irrigation regimes: continuous flooding and AWD. Varying rates of amendment application will be tested to determine its influence on both soil chemistry and methane emissions.

Experimental setup for the glasshouse studies, monitoring, data collection and gas sampling throughout the rice growth stages. 

Understanding the role of microbiome in methane emissions from rice systems

This experiment involved an incubator study designed to isolate and establish a culture protocol for cable bacteria from rice field environments. Additionally, it included extensive DNA sampling from the rhizosphere and endosphere across all project study sites for comprehensive microbiome profiling. The goal was to identify native microbial strains with potential for methane inhibition and oxidation.

Collecting rhizosphere soil samples from rice plants.

Workstream 2 focuses on applied research aimed at testing and validating effective combinations of soil amendments and management practices that can be rapidly scaled for rice farmers across Asia and potentially worldwide. 

The research will explore the impact of AWD in combination with residue incorporation on root-associated and soil microbiomes, with particular attention to methanotrophs and methanogenic bacterial communities in field conditions.

Team Leader: Ando Radanielson

Validation and development of technologies for reducing GHG emissions from rice paddies

This validation trial evaluates mitigation practices to reduce GHG emissions from rice paddies while generating data to improve the ORYZA rice crop model for GHG simulations. Selected through a comprehensive literature review, these mitigation practices are tested alongside field, pot, and incubation trials to develop low-emission rice production recommendations. The study explores how soil amendments under continuous flooding (CF) can lower methane emissions compared to conventional methods, with emission reductions varying based on soil properties and amendment types. It also seeks to identify an optimal amendment rate with methane reduction comparable to the AWD method.

Comparing methane emissions from different rice field management practices, including continuous flooding (CF) and alternate wetting and drying (AWD), to assess the impact of soil amendments on greenhouse gas reduction.

Biochar application optimization for reducing GHG emissions from rice paddies

This study explores the medium- to long-term effects of biochar application on soil health, crop productivity, and greenhouse gas (GHG) emissions in rice-based cropping systems. The goal is to develop practical recommendations for biochar use as a GHG-reducing amendment to support low-carbon rice systems. Applying biochar at farmer-accessible rates is anticipated to provide both immediate and sustained benefits for methane reduction and overall carbon balance, surpassing the effectiveness of higher, one-time application rates primarily focused on soil fertility enhancement.

Evaluating biochar application rates for sustainable rice farming—balancing soil fertility and long-term methane reduction while considering farmer accessibility.

Use of phosphogypsum (PG) for reducing GHG emissions from rice paddies

This experiment evaluates the effectiveness of phosphogypsum (PG), a sulfate-based soil amendment, in reducing methane emissions from rice paddies under both continuous flooding (CF) and AWD water management systems. The study aims to identify the optimal application rate of PG that balances methane reduction with crop productivity and soil health. Different rates of PG are expected to influence both daily and seasonal methane emissions, with an optimal rate potentially achieving effective mitigation under both CF and AWD conditions while maintaining rice yield and soil health.

Investigating phosphogypsum application for methane reduction in rice fields.

Workstream 3 focuses on screening a wide array of rice cultivars to identify the microbial and physiological mechanisms underlying methane emissions. This involves dissecting key traits associated with high and low CH4-emitting varieties, including plant physiological characteristics and root-associated microbiomes.

Team Leader: Amelia Henry

Analyzing rice root traits through core sampling and plant processing to understand growth patterns across different seasons.

Field screening of GHG emissions from different rice varieties

The project aims to gain a deeper mechanistic understanding of methane fluxes to guide the development of low-emission rice varieties while maintaining grain yield performance. This experiment focuses on: (1) assessing variations in greenhouse gas emissions across different rice varieties grown under continuous flooding, (2) identifying key plant traits linked to lower methane emissions for targeted breeding efforts, and (3) optimize the use of the laser-based Trace Gas Analyzer (TGA) for automated sampling and precise quantification of greenhouse gas emissions.

Measuring CH4 and N2O emissions using the Licor Trace Gas Analyzer (TGA). A pump and valve system automate air transfer from chambers for accurate field sampling.

Effective rice crop management involves balancing greenhouse gas (GHG) mitigation, soil carbon sequestration, and the need to sustain crop yields. While experimental research provides valuable insights into optimized management practices, these findings are often limited by the specific conditions under which the trials are conducted. Process-based simulation models, such as ORYZA, offer a broader application by predicting crop performance, GHG emissions, and soil dynamics across diverse environments. This allows for the development of site-specific recommendations and support carbon credit claims.

ORYZA, built on over 30 years of rice research, is renowned for its accurate simulation of rice crop phenology, growth, and yield. Recent updates to the model have enhanced its ability to simulate GHG emissions in response to various water and nitrogen management practices. However, further refinement and validation are needed to improve the model's representation of agronomic practices, such as soil amendments and methane inhibitors, and their effects on both productivity and emissions. 

Workstream 4 of the REMET-Rice project focuses on advancing the ORYZA rice crop model. This includes conducting dedicated field experiments, which are crucial for improving the model’s accuracy in simulating these practices. Once fully calibrated and validated, the modified ORYZA model could provide more reliable insights into the environmental impact of rice production. It could also play a key role in carbon credit methodologies by offering scientifically robust evidence of emission reductions and the implementation of sustainable practices.

Team Leader: Tao Li

Field experiments contribute to improvements of the ORYZA rice crop model. Once validated, the model could support carbon credit methodologies by providing robust scientific evidence of emission reductions and sustainable practices.