Large contribution of soil N<sub>2</sub>O emission to the global warming potential of a large-scale oil palm plantation despite changing from conventional to reduced management practices
<p>Conventional management of oil palm plantations, involving high fertilization rate and herbicide application, results in high yield but with large soil greenhouse gas (GHG) emissions. This study aimed to assess a practical alternative to conventional management, namely reduced fertilization...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2024-01-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/21/513/2024/bg-21-513-2024.pdf |
| Summary: | <p>Conventional management of oil palm plantations, involving high fertilization rate and herbicide application, results in high yield but with large soil greenhouse gas (GHG) emissions. This study aimed to assess a practical alternative to conventional management, namely reduced fertilization with mechanical weeding, to decrease soil GHG emissions without sacrificing production. We established a full factorial experiment with two fertilization rates (conventional and reduced fertilization, equal to nutrients exported via fruit harvest) and two weeding methods (herbicide and mechanical), each with four replicate plots, since 2016 in a <span class="inline-formula">≥</span> 15-year-old, large-scale oil palm plantation in Indonesia. Soil <span class="inline-formula">CO<sub>2</sub></span>, <span class="inline-formula">N<sub>2</sub>O</span>, and <span class="inline-formula">CH<sub>4</sub></span> fluxes were measured during 2019–2020, and yield was measured during 2017–2020. Fresh fruit yield (30 <span class="inline-formula">±</span> 1 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">Mg</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">ha</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="62pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="57f846380ea793de7b2a1f91bd3c529e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-513-2024-ie00001.svg" width="62pt" height="15pt" src="bg-21-513-2024-ie00001.png"/></svg:svg></span></span>) and soil GHG fluxes did not differ among treatments (<span class="inline-formula"><i>P</i>≥</span> 0.11), implying legacy effects of over a decade of conventional management prior to the start of the experiment. Annual soil GHG fluxes were 5.5 <span class="inline-formula">±</span> 0.2 Mg CO<span class="inline-formula"><sub>2</sub></span>-C ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>, 3.6 <span class="inline-formula">±</span> 0.7 kg N<span class="inline-formula"><sub>2</sub></span>O-N ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>, and <span class="inline-formula">−</span>1.5 <span class="inline-formula">±</span> 0.1 kg CH<span class="inline-formula"><sub>4</sub></span>-C ha<span class="inline-formula"><sup>−1</sup></span> yr<span class="inline-formula"><sup>−1</sup></span> across treatments. The palm circle, where fertilizers are commonly applied, covered 18 % of the plantation area but accounted for 79 % of soil <span class="inline-formula">N<sub>2</sub>O</span> emission. The net primary production of this oil palm plantation was 17 150 <span class="inline-formula">±</span> 260 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M25" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">kg</mi><mspace linebreak="nobreak" width="0.125em"/><mi mathvariant="normal">C</mi><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">ha</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="68pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="62f4bff4307f60295cbef239a7f84956"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-513-2024-ie00002.svg" width="68pt" height="15pt" src="bg-21-513-2024-ie00002.png"/></svg:svg></span></span>, but 62 % of this was removed by fruit harvest. The global warming potential of this planation was 3010 <span class="inline-formula">±</span> 750 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M27" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">kg</mi><mspace width="0.125em" linebreak="nobreak"/><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub><mspace linebreak="nobreak" width="0.125em"/><mi mathvariant="normal">eq</mi><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">ha</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="94pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="4069fc3755283d1dd599f670665b4d2e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-513-2024-ie00003.svg" width="94pt" height="16pt" src="bg-21-513-2024-ie00003.png"/></svg:svg></span></span>, of which 55 % was contributed by soil <span class="inline-formula">N<sub>2</sub>O</span> emission and only <span class="inline-formula"><</span> 2 % offset by the soil <span class="inline-formula">CH<sub>4</sub></span> sink.</p> |
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| ISSN: | 1726-4170 1726-4189 |