Digestate in paddy soil – methane emission and carbon sequestration
Purpose: Soils are the largest store of carbon in the biosphere, but soils can also act as the key sources of greenhouse gases. Rice cultivation in paddy soil is anoxic, thus creating an optimal condition for methane production. Digestate, a potential biofertilizer, contains a microbial consortium...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
OICC Press
2025-05-01
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| Series: | International Journal of Recycling of Organic Waste in Agriculture |
| Subjects: | |
| Online Access: | https://oiccpress.com/ijrowa/article/view/16872 |
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| Summary: | Purpose: Soils are the largest store of carbon in the biosphere, but soils can also act as the key sources of greenhouse gases. Rice cultivation in paddy soil is anoxic, thus creating an optimal condition for methane production. Digestate, a potential biofertilizer, contains a microbial consortium adapted for methane production because it comes from biogas production where methane production is optimised. In this study, we explored digestate as fertiliser in paddy soil, focussing on the effects of carbon sequestration and methane emission.
Method: A number of digestates and digestate products were incubated in the soils, both waterlogged and at field capacity. The effects of thermal treatment of the digestates were assessed to understand if the microbial community applied with the digestate played a role.
Results: Carbon dioxide emission was 53% higher in the soil with a history of mineral fertiliser application, than in the soil with digestate application history under waterlogging, at field capacity it was 13% smaller. Methane emissions came later when the digestate was heat-treated, indicating that the microbial community in the digestate could change the timing of emissions, but not the amount. Otherwise, some digestates increased methane emissions, whilst others had little effect. The supply of available carbon appeared to be an important factor to explain differences.
Conclusion: Digestate can increase carbon sequestration in paddy soil, although the interaction between waterlogging and soil history is not fully understood. The microbial community applied with the digestate can make methane emission start earlier, but it does not increase total emission.
Research Highlights
• The microbial community applied with the digestate accelerated methane formation.
• CO2 emission was higher under waterlogging than at field capacity in soil with low organic content.
• Waterlogging decreased methane emission in unamended soil.
• Only digestate where some methane potential was left induced high methane emission.
• Methanogens and methanotrophs abundances dynamics partly explain emission patterns.
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| ISSN: | 2195-3228 2251-7715 |