N fertilization effects on N2O fluxes from oil palm plantation on tropical peatland

Auldry Chaddy,Ryusuke Hatano,Lulie Melling,Kiwamu Ishikura

doi:10.5194/egusphere-egu21-10546

Abstract

&lt;p&gt;Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have a significant influence on soil nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O) emission from oil palm plantation on tropical peatland. Finding a suitable N rate for optimum N uptake efficiency and yield with low environmental impact and production cost is crucial for the economic growth of Malaysia&amp;#8217;s oil palm sector. However, studies on the impact of N fertilizers on N&lt;sub&gt;2&lt;/sub&gt;O emissions&amp;#160;from&amp;#160;tropical peatland are limited. Thus, long-term monitoring was conducted to investigate the effects of N fertilization on soil N&lt;sub&gt;2&lt;/sub&gt;O emissions. This study was conducted in an oil palm (&lt;em&gt;Elaeis guineensis Jacq&lt;/em&gt;.) plantation located in a tropical peatland in Sarawak, Malaysia. Monthly soil N&lt;sub&gt;2&lt;/sub&gt;O fluxes were measured using the closed-chamber method in a control (T1, without N fertilization), and under three different N treatments: low N (T2, 31.1 kg N ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;), moderate N (recommended rate) (T3, 62.2 kg N ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;), and high N (T4, 124.3 kg N ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;), from January 2010 to December 2013 and from January 2016 to December 2017. The only N fertiliser rate to significantly increase (p&lt;0.05) annual cumulative N&lt;sub&gt;2&lt;/sub&gt;O emissions was 124.3 kg N ha&lt;sup&gt;-1&lt;/sup&gt; (T4). Increased&amp;#160;in water-filled pore space (WFPS) (&gt;70%) with a decrease in both N&lt;sub&gt;2&lt;/sub&gt;O flux and nitrate (NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;) implies that complete denitrification has taken place.&amp;#160;Increased in NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;&amp;#160;uptake by oil palm with an increase in WFPS decreased NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; concentration in soil, resulting in the reduction of N&lt;sub&gt;2&lt;/sub&gt;O emission. This study highlights the importance of WFPS on denitrification and &lt;span&gt;N uptake &lt;/span&gt;&lt;span&gt;by oil palm in tropical peatland. This needs to be taken into account for the accurate assessment of N dynamics in oil palm plantations on tropical peatland in order to enhance N fertilization management strategies and counteract anthropogenic activities that produce greenhouse gases.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Keywords: WFPS, oil palm yield, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;, N uptake&lt;/p&gt;

Full Text