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Soil N₂O Emissions under Different N Rates in an Oil Palm Plantation on Tropical Peatland

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Title: Soil N₂O Emissions under Different N Rates in an Oil Palm Plantation on Tropical Peatland
Authors: Chaddy, Auldry Browse this author
Melling, Lulie Browse this author
Ishikura, Kiwamu Browse this author
Hatano, Ryusuke Browse this author →KAKEN DB
Keywords: ground water level (GWL)
water-filled pore space (WFPS)
oil palm yield
nitrification
denitrification
Issue Date: 1-Oct-2019
Publisher: MDPI
Journal Title: Agriculture
Volume: 9
Issue: 10
Start Page: 213
Publisher DOI: 10.3390/agriculture9100213
Abstract: (1) Background: Nitrogen (N) fertilization on drained tropical peatland will likely stimulate peat decomposition and mineralization, enhancing N₂O emission from the peat soil. (2) Methods: A field experiment was conducted to quantify the N₂O emissions from soil in an oil palm plantation (Elaeis guineensis Jacq.) located in a tropical peatland in Sarawak, Malaysia, under different rates of N fertilizers. The study was conducted from January 2010 to December 2013 and resumed from January 2016 to December 2017. Nitrous oxide (N₂O) flux was measured every month using a closed chamber method for four different N rates; control-without N(T1), 31.1 kg N ha⁻¹ yr⁻¹(T2), 62.2 kg N ha⁻¹ yr⁻¹(T3), and 124.3 kg N ha⁻¹ yr⁻¹ (T4); (3) Results: Application of the N fertilizer significantly increased annual cumulative N₂O emissions for T4 only in the years 2010 (p = 0.017), 2011 (p = 0.012), 2012 (p = 0.007), and 2016 (p = 0.048). The highest average annual cumulative N2O emissions were recorded for T4 (41.5 ± 28.7kg N ha⁻¹yr⁻¹), followed by T3 (35.1 ± 25.7kg N ha⁻¹yr⁻¹), T1 (25.2 ± 17.8kg N ha⁻¹yr⁻¹), and T2 (25.1 ± 15.4kg N ha⁻¹yr⁻¹), indicating that the N rates of 62.2kg N ha⁻¹yr⁻¹ and 124.3kg N ha⁻¹yr⁻¹ increased the average annual cumulative N₂O emissions by 39% and 65%, respectively, as compared to the control. The N fertilization had no significant effect on annual oil palm yield (p = 0.994). Alternating between low (deeper than -60cm) and high groundwater level (GWL) (shallower than -60cm) enhanced nitrification during low GWL, further supplying NO₃- for denitrification in the high GWL, and contributing to higher N₂O emissions in high GWL. The emissions of N₂O ranged from 17µg N m⁻² hr⁻¹ to 2447 µg N m⁻² hr⁻¹ and decreased when the water-filled pore space (WFPS) was between 70% and 96%, suggesting the occurrence of complete denitrification. A positive correlation between N₂O emissions and NO₃- at 70-96% WFPS indicated that denitrification increased with increased NO₃- availability. Based on their standardized regression coefficients, the effect of GWL on N₂O emissions increased with increased N rate (p < 0.001). Furthermore, it was found that annual oil palm yields negatively correlated with annual N₂O emission and NO₃- for all treatments. Both nitrification and denitrification increased with increased N availability, making both processes important sources of N₂O in oil palm cultivation on tropical peatland.; and (4) Conclusions: To improve understanding of N₂O mitigation strategies, further studies should consider plant N uptake on N₂O emissions, at least until the completion of the planting.
Rights: https://creativecommons.org/licenses/by/4.0/
Type: article
URI: http://hdl.handle.net/2115/76293
Appears in Collections:農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

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