Fertilization turns a rubber plantation from sink to methane source
<p>The rapid expansion of rubber cultivation, driven by the demand for natural rubber in the tire industry, constitutes a significant land-use change in Southeast Asia. This significant land-use change has reduced soil methane (CH<span class="inline-formula"><sub>4</su...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-08-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/4013/2025/bg-22-4013-2025.pdf |
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| Summary: | <p>The rapid expansion of rubber cultivation, driven by the demand for natural rubber in the tire industry, constitutes a significant land-use change in Southeast Asia. This significant land-use change has reduced soil methane (CH<span class="inline-formula"><sub>4</sub></span>) uptake, thereby weakening atmospheric CH<span class="inline-formula"><sub>4</sub></span> removal over extensive areas. While fertilization is a widespread practice in rubber plantations, its role in further weakening the soil CH<span class="inline-formula"><sub>4</sub></span> sink has remained poorly understood. Over 1.5 years, we measured soil CH<span class="inline-formula"><sub>4</sub></span> fluxes biweekly (every 2 weeks) in an experimental rubber plantation with four distinct fertilization treatments to evaluate their impact on the soil CH<span class="inline-formula"><sub>4</sub></span> uptake. Our findings revealed that fertilization not only reduced soil CH<span class="inline-formula"><sub>4</sub></span> consumption, but also increased soil CH<span class="inline-formula"><sub>4</sub></span> production. The difference in soil CH<span class="inline-formula"><sub>4</sub></span> uptake between unfertilized plots (<span class="inline-formula">−</span>2.9 kg CH<span class="inline-formula"><sub>4</sub></span> ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>) and those with rational fertilization (<span class="inline-formula">−</span>2.1 kg CH<span class="inline-formula"><sub>4</sub></span> ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>) was moderate. Recommended fertilization rates reduced soil CH<span class="inline-formula"><sub>4</sub></span> uptake by 60 % (<span class="inline-formula">−</span>1.1 kg CH<span class="inline-formula"><sub>4</sub></span> ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>), and heavy fertilization transformed the soil into a net source of CH<span class="inline-formula"><sub>4</sub></span> (<span class="inline-formula">+</span>0.3 kg CH<span class="inline-formula"><sub>4</sub></span> ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>). The suppression of soil CH<span class="inline-formula"><sub>4</sub></span> oxidation was likely driven by increased mineral nitrogen in the soil solution and soil acidification, while elevated dissolved organic carbon likely stimulated CH<span class="inline-formula"><sub>4</sub></span> production in the topsoil. Most rubber tree trunks emitted CH<span class="inline-formula"><sub>4</sub></span>, likely of internal origin. Trunk CH<span class="inline-formula"><sub>4</sub></span> fluxes ranged from <span class="inline-formula">−</span>0.10 to 0.51 nmol s<span class="inline-formula"><sup>−1</sup></span> per tree, with no significant fertilization effect. At the national level, adopting rational fertilization practices in Thailand could enhance the net soil CH<span class="inline-formula"><sub>4</sub></span> sink by 5.9 Gg CH<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>. However, this mitigation strategy would have a limited impact on the overall greenhouse gas budget of the agricultural sector in Southeast Asia, unless it is extended to other tree plantations and cropping systems.</p> |
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| ISSN: | 1726-4170 1726-4189 |