Understanding methane emission from stored animal manure: A review to guide model development

Area of Science:

• Environmental Science
• Microbiology
• Climate Science

Background:

• National methane (CH4) inventories rely on simplified IPCC guidelines.
• Current models inadequately represent manure management practices and environmental impacts.
• Accurate CH4 emission calculations from liquid manure require a deeper understanding of microbiological processes.

Purpose of the Study:

• To develop a detailed understanding for accurate CH4 emission models from liquid manure.
• To focus on the microbiological conversion of organic matter to CH4.
• To identify limitations in existing CH4 emission estimation approaches.

Main Methods:

• Review of microbiological conversion of organic matter to CH4 in liquid manure.
• Analysis of factors influencing methane production: environment, microbial communities, mass/electron conservation, limiting steps, inhibition, and temperature.
• Examination of existing estimation approaches and their limitations.

Main Results:

• Methane production is significantly affected by manure temperature, substrate availability and age, and management systems.
• Models must incorporate microbial responses to these variables for accurate CH4 calculations.
• Key variables influencing methane production can be manipulated through management procedures.

Conclusions:

• Accurate CH4 emission models necessitate the inclusion of microbial adaptation algorithms.
• Understanding microbial adaptation to environmental and management variations is crucial.
• Further quantification of hydrolysis kinetics and microbial adaptation is needed for improved CH4 emission modeling.