Coupled abiotic-biotic cycling of nitrous oxide in tropical peatlands

Atmospheric nitrous oxide (N2O) is a potent greenhouse gas thought to be mainly derived from microbial metabolism as part of the denitrification pathway. Here, we report that in unexplored peat soils of Central and South America, N2O production can be driven by abiotic reactions (> 98 %) highly competitive to their enzymatic counterparts. Extracted soil iron positively correlated with in-situ abiotic N2O production determined by isotopic tracers. Moreover, we found that microbial N2O reduction accompanied abiotic production, essentially closing a coupled abiotic-biotic N2O cycle. Anaerobic N2O consumption occurred ubiquitously (pH 6.4-3.7), with proportions of diverse clade II N2O-reducers increasing with consumption rates. Our findings show denitrification in tropical peat soils is not a purely biological process, but rather a 'mosaic' of abiotic and biotic reduction reactions. We predict hydrological and temperature fluctuations differentially affect abiotic and biotic drivers and further contribute to the high N2O flux variation in the region.

Flooding tolerance of four tropical peatland tree species in a nursery trial

In order to facilitate hydrological restoration efforts, initiatives have been conducted to promote tree growth in degraded and rewetted peatlands in Indonesia. For this initiatives to be successful, tree seedlings need to be able to survive flooding episodes, with or without shade. We investigated the survival of different shading and water levels under controlled conditions in a nursery, with artificial rainwater and with peat soils as the medium. The research focused on the fllowing questions (i) whether trees can grow on flooded peat soils; and (ii) which plant traits allow plants to cope with inundation, with or without shade. The four tree species compared ( Shorea balangeran, Cratoxylum arborescens, Nephelium lappaceum, and Durio zibethinus ) include two natural poineer and two farmer-preferred fruit trees. The experiment used as a split-split plot design with 48 treatment combinations and at least 13 tree-level replicates. The study found that S. balangeran and C. arborescens developed adventitious roots to adapt to the inundated conditions. D. zibethinus, S. balangeran and N. lappaceum grew best under moderate (30%) shading levels, while C. arborescens grew best in full sunlight.

Thermal Imaging Study on The Effect of Permeability on Smouldering Behaviour of a Tropical Peat

Smouldering is a slow-burning, low-temperature, flameless combustion, and frequently happens in peatland fires. The smouldering spread occurs because of the parameter achievement in oxygen supply, generated heat, and heat released to the environment. The condition of porous and fibrous peat soils makes oxygen supply easily happens. The difficulty of getting to the location of the burning peatland is one of the problems to extinguish the fire. This study aims to observe with thermal imaging study the effect of peat permeability on smouldering behaviour of a tropical peat sample. Mechanical compaction was applied to reduce permeability and pore value in the central of the peat soil. Then, peat soil is ignited to create the smouldering propagation through the compacted peat area. The combustion process that occurs on the surface is observed by a visual camera and an Infrared FLIR Thermal Camera. The initial results showed a reduction in the smouldering spread rate on the compacted soil region as compared to the undisturbed peat smouldering region. Nevertheless, smouldering combustion of peat still occurred in all regions of the reactor, once the smouldering front could penetrate the compacted region.

Viewpoints on Cooperative Peatland Management: Expectations and Motives of Dutch Farmers

The European Union (EU) is globally the second highest emitter of greenhouse gases from drained peatlands. On the national level, 15% of agricultural peat soils in the Netherlands are responsible for 34% of agricultural emissions. Crucial to any successful policy is a better understanding of the behavioral change it will bring about among the target groups. Thus, we aim to explore farmers’ differing viewpoints to discuss how policy and planning can be improved to ensure landscape-scale climate mitigation on agriculturally used peatlands. Q methodology was used to interview fifteen farmers on Dutch peat soils, whereby 37 statements were ranked in a grid according to their level of agreement. Factor analysis revealed three main viewpoints: farmers with a higher peat proportion show an urgency in continuing to use their land (‘cooperative businesspeople’), while ‘independent opportunists’ are wary of cooperation compromising their sense of autonomy. Farmers who are ‘conditional land stewards’ are open to agriculture without drainage but require appropriate payments to do so. Future policy design must focus on providing support to farmers that go beyond compensation payments by providing information about funding sources as well as potential business models for peatland uses with raised water tables.

Karakteristik Sifat Fisik Tanah Gambut Ogan Komering Ilir

Some areas of South Sumatra Province are peatlands scattered in the eastern part, starting from the districts of Musi Rawas, Musi Banyuasin, Ogan Komering Ilir, Muaraenim, and Banyuasin. Around 769,000 hectares of peatland are located in the Ogan Komering Ilir Regency area. Ogan Komering Ilir Regency is an area prone to forest fires. Therefore, it is necessary to conduct research on the characteristics of peat soils in the Ogan Komering Ilir area so that they can be used as consideration in efforts to prevent peatland fires. Sampling was carried out in Kotarayo Village, (Kayuagung District), SP 1 (Pedamaran Timur District), and Tulung Selapan Ilir Village (Tulung Selapan District). Peat soil samples were taken with ASTM D 7015-04 guidelines, and the physical properties of peat soil were tested for samples from the three locations. Based on its physical properties, peat soil samples are classified according to ASTM D4427-84. From the results of the research on peat soils in Kayuagung, Tulung Selapan, and Pedamaran Timur sub-districts, Ogan Komering Ilir Regency, peat soil samples can be classified as sapric-peat soil.

The influence of feed quality from peat soils on the productivity of cattle

In the context of the implementation of environmental, resource-saving systems of agriculture, research in the system of biogeocenosis is very relevant: soil – plant-feed-animal-livestock products. Peatlands and developed peat soils are a kind of environment for human activity in this system. As a result of many years of research, it was found that perennial grasses grown on peat soils have differences in chemical composition compared to plants grown on mineral soils. They contain more organic matter and raw protein. However, their digestibility of nutrients is lower than in herbs grown on mineral soils. Therefore, for a full-fledged balanced feeding of cows, the realization of the genetic potential of animal productivity, and the preservation of their health, scientifically-based diets are necessary, developed on the basis of bulky feeds obtained from peat and developed soils, with the introduction of appropriate feed additives in them.

Growth and P absorption of Fibraurea tinctoria lour in peat soil with an amendment

One of the ways to maintain and increase immunity during the COVID-19 pandemic is by consuming the medicinal plant. Indonesia has many medicinal plants, one of which is ‘akar kuning’ (Fibraurea tinctoria Lour). F. tinctoria is a wild plant commonly found in Kalimantan and has not been widely cultivated. Therefore, efforts to develop need to be made, especially in peat soil. An approach to addressing the problem in peat soils is adding zeolite amendments and NPK fertilizer to increase growth. Therefore, preliminary research was conducted to determine the growth and P absorption of F tinctoria in peat soil. The study used Zeolite (0 and 2.5 g polybag−1) and NPK fertilizer with three levels (3, 6, 9 g plant−1). The combination treatments were arranged factorially on a completely randomized design. The study shows different responses to the leaf number, root volume, and root dry weight. Tendril length and P absorption increased along with the increase of Zeolite and NPK application.

Active virus-host interactions at sub-freezing temperatures in Arctic peat soil

Background Winter carbon loss in northern ecosystems is estimated to be greater than the average growing season carbon uptake and is primarily driven by microbial decomposers. Viruses modulate microbial carbon cycling via induced mortality and metabolic controls, but it is unknown whether viruses are active under winter conditions (anoxic and sub-freezing temperatures). Results We used stable isotope probing (SIP) targeted metagenomics to reveal the genomic potential of active soil microbial populations under simulated winter conditions, with an emphasis on viruses and virus-host dynamics. Arctic peat soils from the Bonanza Creek Long-Term Ecological Research site in Alaska were incubated under sub-freezing anoxic conditions with H218O or natural abundance water for 184 and 370 days. We sequenced 23 SIP-metagenomes and measured carbon dioxide (CO2) efflux throughout the experiment. We identified 46 bacterial populations (spanning 9 phyla) and 243 viral populations that actively took up 18O in soil and respired CO2 throughout the incubation. Active bacterial populations represented only a small portion of the detected microbial community and were capable of fermentation and organic matter degradation. In contrast, active viral populations represented a large portion of the detected viral community and one third were linked to active bacterial populations. We identified 86 auxiliary metabolic genes and other environmentally relevant genes. The majority of these genes were carried by active viral populations and had diverse functions such as carbon utilization and scavenging that could provide their host with a fitness advantage for utilizing much-needed carbon sources or acquiring essential nutrients. Conclusions Overall, there was a stark difference in the identity and function of the active bacterial and viral community compared to the unlabeled community that would have been overlooked with a non-targeted standard metagenomic analysis. Our results illustrate that substantial active virus-host interactions occur in sub-freezing anoxic conditions and highlight viruses as a major community-structuring agent that likely modulates carbon loss in peat soils during winter, which may be pivotal for understanding the future fate of arctic soils' vast carbon stocks.