Soil greenhouse gas emissions from inorganic fertilizers and recycled oil palm waste products from Indonesian oil palm plantations

Abstract

A continuous rise in the global demand for palm oil has resulted in the large‐scale expansion of oil palm plantations and generated environmental controversy. Efforts to increase the sustainability of oil palm cultivation include the recycling of oil mill and pruning residues in the field, but this may increase soil methane (CH4) emissions. This study reports the results of yearlong field‐based measurements of soil nitrous oxide (N2O) and CH4 emissions from commercial plantations in North Sumatra, Indonesia. One experiment investigated the effects of soil‐water saturation on N2O and CH4 emissions from inorganic fertilizers and organic amendments by simulating 25 mm rainfall per day for 21 days. Three additional experiments focused on emissions from (a) inorganic fertilizer (urea), (b) combination of enriched mulch with urea and (c) organic amendments (empty fruit bunches, enriched mulch and pruned oil palm fronds) applied in different doses and spatial layouts (placed in inter‐row zones, piles, patches or bands) for a full year. The higher dose of urea led to a significantly higher N2O emissions with the emission factors ranging from 2.4% to 2.7% in the long‐term experiment, which is considerably higher than the IPCC standard of 1%. Organic amendments were a significant source of both N2O and CH4 emissions, but N2O emissions from organic amendments were 66%–86% lower than those from inorganic fertilizers. Organic amendments applied in piles emitted 63% and 71% more N2O and CH4, respectively, than when spread out. With twice the dose of organic amendments, cumulative emissions were up to three times greater. The (simulated) rainwater experiment showed that the increase in precipitation led to a significant increase in N2O emissions significantly, suggesting that the time of fertilization is a critical management option for reducing emissions. The results from this study could therefore help guide residue and nutrient management practices to reduce emissions while ensuring better nutrient recycling for sustainable oil palm production systems.

Mulching with pruned fronds promotes the internal soil N cycling and soil fertility in a large-scale oil palm plantation

“…fertilization rates ranged from 48 to 88 kg N, 21-38 kg P and 40-73 kg K ha -1 yr -1 ; Allen et al 2015) and the frond-stacked area is not spatially distinct as in our large-scale plantation. Soil N 2 O and N 2 fluxes are not yet quantified at our studied plantation but N 2 O emissions have been reported for frond-stacked area of a large-scale oil palm plantation in Medan, Sumatra (Rahman et al 2019) and for interrows and palm circle of a plot near our site (Hassler et al 2017). For this data synthesis, we used these reported N 2 O fluxes and we estimated N 2 emissions using the global N 2 O:(N 2 ?…”

“…Jambi province, Sumatra; Clough et al 2016). The intensive management in large-scale plantations has been linked to negative environmental impacts: high N fertilization rates result in large N 2 O emissions (Hassler et al 2017;Rahman et al 2019) and N leaching losses (Formaglio et al 2020), potentially diminishing water quality (Comte et al 2012), whilst herbicides remove understory vegetation and reduce soil cover, possibly affecting soil biodiversity (Ashton-Butt et al 2018) and soil erosion (Moradi et al 2015). Moreover, oil palm plantations have strongly reduced ecosystem functions (e.g.…”

Nitrogen in Atmospheric Wet Depositions Over the East Indian Ocean and West Pacific Ocean: Spatial Variability, Source Identification, and Potential Influences

“…Besides, a significant fraction of peatland in Southeast Asia has been changed to oil palm plantations (Jiang et al, 2019). The releasing rate of N 2 O from these peatlands is significantly higher (emission factors: 2.4-2.7%) than the IPCC standard on a global scale (1%; Rahman et al, 2019). Though low-level application of chemical fertilizer, the rapid and active production from peatland could contribute to atmospheric NO x .…”

Why do We Know So Much and Yet So Little? A Scoping Review of Willingness to Pay for Human Excreta Derived Material in Agriculture

“…The design of the choice experiment is also critical in stated preference approaches. Experimental designs need to be explicit regarding the statistical power [73], information order or scope effects in CV [127], attribute nonattendance [128,129], omitted attributes, bid amount effects, and the effects of the selected optimization criteria [124]. Regarding statistical power, none of the included studies included a formal calculation of sample size or power test.…”