Peatlands are carbon-rich wetlands that store large amounts of organic matter due to their water-saturated, low-oxygen conditions. Naturally, they emit methane but sequester carbon dioxide and nitrous oxide. However, agricultural conversion involving drainage, fertilization, and soil disturbance disrupts these properties, accelerating organic matter decomposition and releasing vast quantities of carbon dioxide (CO₂) and nitrous oxide (N₂O). Particularly in tropical regions, N₂O emissions can reach up to 700 kg N ha⁻¹ annually—significantly higher than in other soil types. The compounded impact of rising temperatures and mismanaged land use makes tropical peatlands both a climate vulnerability and an opportunity. Due to these challenges, deeper investigations into emission mechanisms and sustainable mitigation strategies are urgently needed.
In a recent invited perspective published (DOI: 10.1016/j.pedsph.2023.12.010) in the Pedosphere journal (Vol. 35, Issue 1, January 2025), Professor Ryusuke Hatano from Hokkaido University examined the effects of agricultural activities on greenhouse gas emissions from tropical peat soils, with a focus on nitrous oxide. Drawing upon field data and meta-analyses across Southeast Asia, the article underscores the critical role of soil conditions, nitrogen fertilization, and water management in influencing N₂O dynamics, offering insights into mitigation strategies for sustainable land use in tropical peatlands.
The review highlights how tropical peatlands, when drained and cultivated, shift from greenhouse gas sinks to powerful sources of N₂O and CO₂. For instance, a vegetable field in Indonesia released over 850 kg N ha⁻¹ year⁻¹ of N₂O, even without nitrogen fertilization. Such emissions are linked to increased topsoil nitrate levels and water-filled pore space (WFPS) exceeding 60%. Conversely, long-term observations in Malaysian oil palm plantations showed that N₂O emissions can decline as plantations mature, driven by improved plant nitrogen uptake and rising WFPS levels above 70%, which may facilitate complete denitrification.
Furthermore, peat decomposition—accelerated by low groundwater levels and excessive fertilization—contributes to elevated nitrogen availability. The study also points to microbial dynamics: acid-tolerant denitrifiers and ammonia-oxidizing archaea play crucial roles in sustaining high N₂O emissions. Importantly, suppression of emissions is observed when surface soils retain moisture and the easily decomposable organic matter is exhausted, leading to higher C/N ratios and decreased decomposition. These findings underscore the need to balance drainage, fertilization, and crop development stages to limit environmental harm while maintaining productivity.
“Although peatlands cover a relatively small fraction of global agricultural land, their impact on greenhouse gas emissions is disproportionately large,” says Prof. Ryusuke Hatano, the paper’s author. “Our research suggests that emission control is possible with careful management of water levels and nitrogen inputs. Long-term monitoring and integrated strategies tailored to site-specific conditions will be essential for sustainable peatland agriculture in the tropics.”
The findings offer practical guidance for mitigating N₂O emissions from tropical peatland agriculture. Strategies such as moderating nitrogen fertilizer use, maintaining high WFPS, and promoting plant nitrogen uptake can significantly reduce emissions. In degraded areas, rewetting and ecological restoration have shown potential in restoring natural carbon dynamics. With climate change intensifying decomposition rates, sustainable management of peatlands is critical not only for emission control but also for reducing fire risks and preserving ecosystem health. These insights contribute to international efforts aimed at achieving carbon neutrality and protecting vulnerable wetland ecosystems.
###
References
DOI
10.1016/j.pedsph.2023.12.010
Original Source URL
https://doi.org/10.1016/j.pedsph.2023.12.010
About Pedosphere
Pedosphere is a peer-reviewed international journal established in 1991 and published bimonthly in English by Elsevier and Science Press. It is jointly sponsored by the Soil Science Society of China and the Institute of Soil Science, Chinese Academy of Sciences, in collaboration with five leading Chinese institutions in soil science. Under the editorship of Prof. Shen Ren-Fang, the journal publishes high-quality original research and reviews spanning the full spectrum of soil science, including environmental science, agriculture, ecology, bioscience, and geoscience. Topics of interest include soil physics, chemistry, biology, fertility, plant nutrition, conservation, and global change. All submissions undergo rigorous double-blind peer review by an international editorial board and expert panel. Pedosphere is indexed in major databases such as SCI Expanded, SCOPUS, BIOSIS, CAB Abstracts, and CNKI, making it a widely recognized platform for advancing soil science research globally.