Abstract The main challenge of planting oil palm on deep peat is naturally acidic soil pH which affects rooting development and activity and uptake of nutrients. Considering one life cycle of oil ...palm can be up to ≥20 years, ensuring optimum growth of palms since its initial planting is essential. Calcium carbonate (CaCO 3 ) application is a standard practice to increase soil pH, including on peat soils. However, the effective rate and effects of its application to palm growth are still lacking. This trial is aimed to see the effect of CaCO 3 application on the vegetative growth of oil palms planted on deep peat in the initial years of planting. The trial was conducted in an oil palm plantation in Pangkalan Kerinci-Riau with a split-plot randomized complete block design. Basal application of CaCO 3 for the first three consecutive years of planting with three different rates and additional rates of CaCO 3 and liquid lime per palm basis were the main and sub-treatments of this trial. Significant differences were found in frond length, leaf area, leaf area index, and frond dry weight at the immature stage in which palms treated with basal CaCO 3 showed better growth. At the young mature stage, significant differences were found only in leaf area, leaf area index, and the number of green fronds. A significant difference for sub-treatment was found only in the leaf area index. The result indicated that application of CaCO 3 as basal application during immature stage could improve palm’s growth whereas additional CaCO 3 per palm basis may not necessarily result in better growth.
This study investigates the factors controlling the soil CO₂ and CH₄ fluxes and quantifies annual cumulative soil respiration (R S), heterotrophic respiration (RH), and soil CH₄ emission in an ...undrained forest on tropical peat by continuous measurement using an automated chamber system for 2 years. Daily mean soil CO₂ flux was increased by lowering groundwater level (GWL), which indicates oxidative peat decomposition is promoted by the enhancement of aeration. On the other hand, soil CH₄ flux showed a bell-shaped relationship with GWL, which suggested that the development of anaerobic conditions promoted CH₄ production by the rise in GWL, whereas hydrostatic pressure suppressed CH₄ diffusion when the GWL was above the peat surface. Mean annual gap-filled CO₂ emissions were 926 ± 610 and 891 ± 476 g C m⁻² y⁻¹ (mean ± 1 SD) for RS (n = 10) and RH (n = 6), respectively, and were not significantly different from each other. The annual RH in this study was similar to that of previous studies despite the higher annual mean GWL in this study, possibly due to the inclusion of litter decomposition in contrast to most of the previous studies in tropical peatland. Mean annual gap-filled CH₄ emission was 4.32 ± 3.95 g C m⁻² y⁻¹ (n = 9), which was the high end of the previous studies in tropical peatland due to higher annual mean GWL in this study. In conclusion, RS was lower and CH₄ emission was higher in the undrained peat swamp forest than those previously reported for drained and disturbed forests on tropical peat.
Saltwater intrusion is a significant threat to the structure and ecology of inland and coastal freshwater wetlands, altering biogeochemical cycling and disrupting important ecosystem services. As sea ...level rises along the Florida coast, the saltwater interface progressively moves further inland reaching freshwater soils previously unexposed to saltwater. One result of this soil salinization is a phenomenon called peat collapse which is currently observable along the South Florida coastline. While previous studies have proposed conceptual models to explain peat collapse many uncertainties still exist regarding the physical mechanisms that trigger this phenomenon. In this study we use a unique combination of laboratory and field‐based measurements using geophysical methods, deformation rods, gas traps, time‐lapse photography, and hydraulic conductivity measurements to investigate the effects of salinization on the physical properties of peat soils across a salinity gradient in the southwestern Everglades. Our results show that freshwater peat soils have about three times greater degree of pore dilation when compared to peat soils previously exposed to saltwater conditions. Differences in soil surface deformation were also observed and related to differences in the soil matrix physical integrity across the salinity gradient. This work also uses electrical resistivity imaging surveys to image areas of peat collapse and demonstrates: (a) the role of salinity in the development of collapse features; and (b) the apparent lack of evidence to suggest subsurface lithological controls on the development of collapse features. A simplified conceptual framework for better understanding peat collapse and pock formation is presented.
Plain Language Summary
Sea‐level rise is a threat to coastal wetland systems like the Everglades. Saltwater intrusion into previously freshwater areas, or salinization, can (a) negatively affect vegetation, (b) cause changes to hydrology/water chemistry, and (c) lead to a process called peat collapse. Peat collapse is a poorly understood but increasingly common type of shallow subsidence in coastal wetlands that is related to losses in soil strength which can lead to an elevation loss below a level where plants could naturally recover. In this study, we combined field‐ and laboratory‐based techniques to understand the effects of salinization on the physical properties of wetland soils in the Everglades (particularly related to peat pore dilation) that may contribute to peat collapse. Our results show that peat soils previously unexposed to salinization had a greater degree of pore dilation than peat soils that had been previously exposed to salinization. Pore dilation can contribute to peat collapse by enhancing compaction during dry periods and decreasing soil strength through excessive swelling. This work also shows no evidence that areas of peat collapse are controlled by deeper geological features such as sinkholes. This research is relevant for management decisions in the Everglades as sea‐levels rise through the 21st century.
Key Points
Saltwater intrusion in peat soils results in pore dilation of the peat matrix and a subsequent increase in hydraulic conductivity
The degree of pore dilation is smaller in peat previously exposed to elevated salinity conditions than previously unexposed freshwater peat
Geophysical surveys provided no evidence to conclude that pock features are lithologically controlled by karst dissolution formations
Peatlands historically have acted as a C sink because C-fixation rates exceeded the rate of heterotrophic decomposition. Under future warmer conditions predicted for higher latitudes, however, that ...balance may shift towards higher rates of heterotrophic respiration leading to the release of previously stored C as CO2 and CH4. The Spruce and Peatlands Response Under Changing Environments (SPRUCE) experiment is designed to test the response of peatlands to climate forcing using a series of warmed enclosures in combination with peat below-ground heating from 0 to +9°C above ambient conditions. This experimental design allowed a test of chemical changes occurring within peatland soils following five years of warming. We analyzed samples in the uppermost 2m of peat using Fourier Transform Infrared Spectroscopy (FT-IR) to quantify the relative abundance of carbohydrate and aromatic compounds in the peat. The peat soils were subjected to deep peat heating (DPH) beginning in June of 2014 followed by whole ecosystem warming (WEW) in August of 2015. We found that the relative amounts of labile and recalcitrant chemical compound groups across the full peat depth interval did not significantly change after five years of exposure to warming. This appears the case even though previous studies have shown that net C losses and loss of bulk peat mass to be instability over that time period. Results suggest that the current store of carbon in peatlands are largely compositionally stable leading to no changes the in the ratio of chemical moieties on the initial four-year timescale of this experiment.
Drainage of peatlands causes severe environmental damage, including high greenhouse gas emissions. Peatland rewetting substantially lowers these emissions. After rewetting, paludiculture (i.e. ...agriculture and forestry on wet peatlands) is a promising land use option. In Northeast Germany (291,361 ha of peatland) a multi-stakeholder discussion process about the implementation of paludiculture took place in 2016/2017. Currently, 57% of the peatland area is used for agriculture (7% as arable land, 50% as permanent grassland), causing greenhouse gas emissions of 4.5 Mt CO
2
eq a
−1
. By rewetting and implementing paludiculture, up to 3 Mt CO
2
eq a
−1
from peat soils could be avoided. To safeguard interests of both nature conservation and agriculture, the different types of paludiculture were grouped into ‘cropping paludiculture’ and ‘permanent grassland paludiculture’. Based on land legislation and plans, a paludiculture land classification was developed. On 52% (85,468 ha) of the agriculturally used peatlands any type of paludiculture may be implemented. On 30% (49,929 ha), both cropping and permanent grassland paludiculture types are possible depending on administrative check. On 17% (28,827 ha), nature conservation restrictions allow only permanent grassland paludiculture. We recommend using this planning approach in all regions with high greenhouse gas emissions from drained peatlands to avoid land use conflicts.
We studied the consequences of a fire that affected 29 ha of a drained forested raised bog in Tver oblast, Central European Russia. The drainage network consisted of open 1-m-deep ditches with 60 to ...160 m ditch spacing. The groundwater level (GWL) varied within the studied drained bog. We used the method of assessing the loss of soil carbon (C) based on the difference between the ash concentration in the burnt peat of the upper layer and underlying unburnt layers. The carbon loss was higher near the drainage ditches than in the sites remote from ditches. The sample median values of carbon loss (kg C/m
2
) were estimated at 0.37 near the drainage ditches and at 0.22 for the remote sites with a distance of 160 m between ditches. They increased to 2.23 and 0.79 near and far from the drainage ditches for 106 m ditch spacing, and ranged from 1.13 to 2.10 near the drainage ditches and were equal to 0.45 at the remote sites for 60 m ditch spacing. The maximum loss of C was at the bog margin with the 70-cm-deep GWL; the sample median was equal to 2.97 kg C/m
2
. The results obtained for C loss from the wildfire on the raised bog agree with the estimates obtained by other authors (1.45–4.90 kg C/m
2
) and confirm the importance of taking such loss into account in the estimates of the carbon budget of peat soils (Histosols).
Summary
Mining operations produce large quantities of wastewater. At a mine site in Northern Finland, two natural peatlands are used for the treatment of mining‐influenced waters with high ...concentrations of sulphate and potentially toxic arsenic (As). In the present study, As removal and the involved microbial processes in those treatment peatlands (TPs) were assessed. Arsenic‐metabolizing microorganisms were abundant in peat soil from both TPs (up to 108 cells gdw−1), with arsenate respirers being about 100 times more abundant than arsenite oxidizers. In uninhibited microcosm incubations, supplemented arsenite was oxidized under oxic conditions and supplemented arsenate was reduced under anoxic conditions, while little to no oxidation/reduction was observed in NaN3‐inhibited microcosms, indicating high As‐turnover potential of peat microbes. Formation of thioarsenates was observed in anoxic microcosms. Sequencing of the functional genemarkers aioA (arsenite oxidizers), arrA (arsenate respirers) and arsC (detoxifying arsenate reducers) demonstrated high diversity of the As‐metabolizing microbial community. The microbial community composition differed between the two TPs, which may have affected As removal efficiencies. In the present situation, arsenate reduction is likely the dominant net process and contributes substantially to As removal. Changes in TP usage (e.g. mine closure) with lowered water tables and heightened oxygen availability in peat might lead to re‐oxidation and re‐mobilization of bound arsenite.
Utricularia multifida is carnivorous bladderwort from Western Australia and belongs to a phylogenetically early-diverging lineage of the genus. We present a prey spectrum analysis resulting from a ...snapshot sampling of 17 traps-the first of this species to our knowledge. The most abundant prey groups were Ostracoda, Copepoda, and Cladocera. The genus cf. Cypretta (Cyprididae, Ostracoda) was the predominant prey. However, a high variety of other prey organisms with different taxonomic backgrounds was also detected. Our results indicate that U. multifida may potentially be specialized in capturing substrate-bound prey. Future approaches should sample plants from different localities to allow for robust comparative analyses.
Abstract
Peat soils have low fertility and are very acidic. Applications of plant growth-promoting rhizobacteria (PGPR) and bionanomaterial membranes (BNMs) have high potentials to alter soil pH. ...However, both applications have never been applied, especially in peat soils. This research aimed to analyze the effect of PGPR and BNMs applications on the chemical properties of peat soils in agroforestry sites. The method used was the sampling of disturbed peat soil. The results showed that after the application of dolomite, manure, PGPR and BNMs, pH values change from very acidic (3.60) to slightly alkaline (7.65), CN ratio from very low (1.20) to high (16), C-organic still very high (43.47%), N-total from very low (1.20%) to very high (1.47%), P-potential from moderate (26.18 mg/100g) to very high (3764.04 mg/100g), Ca-dd from low (4.11 cmol/Kg) to very high (31.59 cmol/kg), K-dd still very high (1.24 cmol/Kg), Mg-dd from high (3.72 cmol/Kg) to very high (23.68 cmol/Kg), Al-dd from very high (5.66 cmol/kg) to low (<0.05 cmol/kg), and base saturation from very low (10.36% ) to very high (100%). The soil fertility was more fertile. The applications of PGPR and BNMs are recommended to improve the peat soil fertility quickly.
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