Tropical Peat Soil Research Articles

Tropical peat soil changes across successive oil palm generations in Sarawak, Malaysia

Oil palm is commonly replanted once reaching the end of its productive lifespan. This cyclical planting practice in oil palm plantations could have long-term implications for the humification and properties of tropical peat soil. This study aimed to investigate the changes observed across successive generations of oil palm plantations in Sarawak, Malaysia. Fourier Transform Infrared Spectroscopy (FTIR) was applied to examine the quality of the Soil Organic Matter (SOM), specifically the functional groups, humification index, Hydrophobicity Index (HI), and Degree of Degradation (DDI). Overall, the peat humification trend was in the order of 2nd Gen > Forest >1st Gen. The higher presence of recalcitrant compounds of lignin in the soil was attributed to the higher HI and lower DDI in the 2nd Gen. The relationship between the Pyrophosphate Solubility Index (PSI) and the humification index further revealed a significant increase in the relative abundance of humic substances with the maturity of degraded organic matter. These findings suggest a notable transition, implicating a shift towards a more stable form of SOM over the long-term utilization of tropical peatland for oil palm plantations. This is characterised by a significant increase in the relative abundance of aromatic, phenolic, and carboxylic functional groups. The study also highlights the need for further research on the linkage between these changes and greenhouse gas emissions to enhance our understanding of the long-term biogeochemical cycle of oil palm on tropical peatlands.

CO2 emissions of tropical peat soils under controlled groundwater table depths: A laboratory-based experiment

The groundwater table (GWT) is widely recognized as a key factor influencing CO2 emissions in tropical peatlands. However, previous studies investigating this relationship have reported diverse results. This variability likely stems from the dynamic nature of field-based groundwater conditions. To address this, our study investigated the relationship between controlled GWT and CO2 emissions in a laboratory experiment using PVC columns filled with peat soil. GWT depths were adjusted to 20 cm, 30 cm, 40 cm, 50 cm, and 60 cm within a large container filled with peat pore water. CO2 emissions were measured using an Infra Red Gas Analyzer - Environmental Gas Monitoring-4 instrument, with a closed-chamber system. Our findings revealed significant differences in CO2 emissions between treatments, except for the transition from 20 cm to 30 cm GWT. Correlation analysis showed a positive correlation (R² = 0.25). Notably, CO2 emission factor values based on average yearly emission rates displayed a substantial increase with decreasing GWT, exhibiting a strong exponential relationship (R² = 0.99).

Spatial variations in heterotrophic respiration from oil palm plantations on tropical peat soils

Spatial variations in heterotrophic respiration from oil palm plantations on tropical peat soils

Utilization Of Soil Ameliorant To Control Emission In Oil Palm Plantation On Tropical Peat Soil

Development of oil palm plantation areas today is increasingly leading to marginal areas, particularly on peatlands. However, development of peatland as agricultural land or as oil palm plantation has the potential to cause peatland to change from a carbon sink into a source of carbon emission. This objective of this research to determine the effect of utilization soil ameliorant to oil palm yield production and in controlling carbon emission and its impact to soil peat chemical properties. The research was conducted in Rokan Hilir district, Riau. The study was carried out in a randomized block design with three replications and three levels of soil ameliorant. The results show that application of high rate soil ameliorant significantly increase FFB yield relatively from control plot. Based on observational data for two months after first application of boiler ash, the CO2 emission was tends to decrease in plot that get the application of soil ameliorant compared to the control plot. Application of 1.5 tonne/ha/yr of ameliorant give the lowest CO2 emission value. Improvement of soil peat chemical properties by application of boiler ash as soil ameliorant also observed in this study, where the high rate of soil ameliorant significantly improves soil pH and also tends to increase total Potassium and Cation Exchange Capacity (CEC).

Effects of maintaining higher water level on the yield of oil palm plantations planted on tropical peat soils.

Effects of maintaining higher water level on the yield of oil palm plantations planted on tropical peat soils.

Minimizing Carbon Dioxide Emissions with Clinoptilolite Zeolite in Moris Pineapple Cultivation on Drained Sapric Soils

Drained tropical peat soils for agriculture emit more carbon dioxide (CO2) into the atmosphere from their stored carbon compared with their pristine state. Field and laboratory experiments were conducted to assess whether the natural zeolite of the clinoptilolite (ZeoC) species could be included in the pineapple fertilization program to decrease the CO2 emissions from tropical sapric soils. The static closed-chamber and laboratory incubation methods were used to determine the effects of ZeoC on the CO2 emitted from a drained sapric soil planted with Moris pineapple. The treatments assessed were as follows: (a) suggested ratio of ZeoC (5 g, 10 g, 14 g, and 20 g of ZeoC) and 20 g compound NPK 30:1:32 fertilizer, enumerated based on the pineapple plant requirement; (b) 20 g of compound NPK 30:1:32 fertilizer only; and (c) unfertilized sapric soils. The drained sapric soils amended with ZeoC (rate of 5 g to 20 g/plant) minimized the CO2 emissions compared with those without the ZeoC, because of the physical and chemical sorption of organic compounds and polar CO2 onto the lattices of ZeoC, which inhibited organic matter decomposition. ZeoC fertilization reduces sapric soil acidity and improves Moris pineapple fruit quality attributes and yield. Monthly pineapple fertilization with ZeoC at the vegetative and flowering phases is an alternative agronomic strategy to reduce CO2 emissions. This approach does not reduce pineapple yield on drained tropical sapric soils.

Nutrient Uptake in Different Maize Varieties (Zea mays L.) Planted in Tropical Peat Materials

Oligotrophic tropical peat soils are usually deemed unsuitable for cropping common crops such as maize due to low pH and nutrient deficiency. This research aims to compare potassium, calcium, and magnesium uptake between different varieties of maize planted in two types of peat materials. This study investigated the growth of selected maize varieties by comparing the nutrient uptake between three different varieties of maize (V1-Asia Manis, V2-Super A, and V3-Pearl Waxy) planted on hemic and sapric, respectively, without any application of fertilisers. Significant interactions were found where different maize varieties responded differently in the nutrient uptake when planted in different peat materials. Super A (V2) significantly recorded the highest uptake for all nutrients (679.71 mg) when planted in hemic, followed by V1 (422.03 mg) and V3 (314.77 mg) when planted in sapric. Super A was found to be superior to the two varieties, where it was more efficient in absorbing nutrients from the peat materials, having significantly higher dry matter weight (26.37 g) than V1 (19.26 g) and V3 (13.67 g). Hemic and sapric could support the growth of all three maize varieties up till the tasselling stage without any fertiliser application.

Impacts of agricultural drainage on the quantity and quality of tropical peat soil organic matter in different types of forests

Tropical peatlands serve as huge carbon (C) pools in the global C balance, and degradation due to agricultural use is a major concern. The objective of the present study was to examine the relationship between the C loss rate in agriculturally drained tropical peat soils in relation to groundwater level (GWL) and the chemical structure of the resulting soil organic matter (SOM). Soil mesocosms containing three peat soils collected from three forest types in Malaysia, Mixed peat swamp (MPS), Alan Batu (ABt), and Alan Bunga (ABg) forests, which are classified based on dominant plant species, species diversity, and forest structure, were buried in an oil palm plantation for a period of five years. Soil samples packed in the top layer (0–20 cm depth) and the bottom (60–80 cm depth) layer were then analyzed and the results were compared with the initial values for these soils. Weight loss, total C and N contents, ash content, and pyrophosphate solubility index (PSI; an index of the degree of humification) were measured. Changes in the chemical structure of the SOC were investigated using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy with phase-adjusted spinning side bands and thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry (THM-GC/MS). The C loss in the MPS forest soil, 2–12%, was smaller than that in the ABt and ABg forest soils, 20–37%, especially in the bottom layer. The higher C loss in the ABt and ABg soils, without significant difference between the top and bottom layers, can be attributed to the greater accumulation of less decomposed plant components as evidenced by the larger yields of lignin-derived phenols and polysaccharide-related compounds in THM-GC/MS analysis. The C composition as estimated by 13C NMR did not vary during incubation of the ABt and ABg soils while the yields of lignin-derived and other phenols as well as polysaccharide-related compounds in THM-GC/MS were decreased, especially in the top layer. These findings suggest that plant components with a low degree of decomposition are susceptible to drainage regardless of their structure. The progression of the oxidative degradation of lignin in the top layer of all soils was also suggested by the increases in PSI and the vanillic acid/vanillin ratio. The % O-alkyl C and % alkyl C may control the rate of C loss positively and negatively, respectively. PSI also appears to be useful for roughly estimating the decomposability of tropical peat SOM in various GWLs.

Influence of Water Table and Peat Thickness on Dissolved Organic Carbon of Tropical Peat Soil with Sulfidic Substratum from Central Kalimantan, Indonesia

Peatlands are important due to their high carbon storage, their role in suppressing climate change processes, and their importance for local and global communities’ livelihood. Large amounts of organic carbon pools in peatlands can be released into the environment as gaseous emitted carbon and lost through waterways (fluvial). The carbon released through the water stream consists of organic and inorganic forms and is partly in the form of CO2 and CH4 gases. The organic form consists of dissolved organic carbon (DOC) and particulate organic carbon, where DOC is the most dominant organic carbon in water sourced from peatlands. This research's objectives were to study the DOC concentration of peat water resulting from the hydrological condition's difference and the peat thickness overlaying the sulfidic substratum. The study was carried out in the Pangkoh area of Pulang Pisau district of Central Kalimantan. Peat water is taken on PVC pipes installed on each plot representing different peat thicknesses (deep, moderate, and shallow peat) at a depth of 25, 50, 100, 150, 200, and 250 cm from the soil surface. The water sampling was conducted on the peak wet season, during the transition from wet season to dry season and during the peak dry season. The results showed that DOC was influenced by peat thickness, depth of sulfidic material, and groundwater level. The release of DOC is higher from the deep peat than from the thin and moderate peat. The difference in DOC concentration between peat thickness is also related to the electrical conductivity of the peat water. The results showed a negative correlation between electrical conductivity and DOC concentration. The negative correlation was significant in the observation of the rainy and dry seasons, while in the transitional season, it was not significant.

Lalombi Tropical Peat Soil Improvement Using Iron Oxide admixture and Cement

Peat soil has a relatively high water content of up to 400%. With a high moisture content, peat soil can hinder construction work. For this reason, in construction planning, an investigation must be carried out on the characteristics and strength of the soil, especially the properties of the soil that affect the bearing capacity of the soil to withstand the load of the construction on it. This study aimed to determine the characteristics and changes in the bearing capacity of peat soil after mixing with cement and iron oxide admixture. The variation of mixing iron oxide is 0%, 4%, 8%, and 16%, while for variation of cement mixture is 5%. This research was conducted on the soil, including testing physical and mechanical properties. Engineering properties tests include direct shear and consolidation tests. This research conducted the elemental chemical content in peat soil and SEM (Scanning Electron Microscope) test. Based on the classification of peat soil at this location with an ash content-value of 29.41%, it can be classified as High Ash Peat (peat with ash content > 25%). In the direct shear test, the cohesion value and the shear angle continued to increase as the percentage of the iron oxide mixture increased to 16%, where the shear angle changed from 7.60º to 45°. In the consolidation test, the original soil Cc value of 0.00820 decreased with the addition of iron oxide to 16%; the Cc value decreased to 0.00277. The decrease in Cc indicates that the soil becomes easily compacted, and The value of the Coefficient of Consolidation (Cv) on peat soil was 0.00535 cm²/sec. The most significant increase in the original soil with a mixture of 16% iron oxide was 0.01463 cm²/sec. The Chemical results have been given a mixture of 16% iron oxide and 5% cement, the change of C (Carbon), Fe (Ferrum) and Ca (Calcium). The value of O (Oxygen) in peat soil was 48.05% and then decreased to 43.67%, this indicates that the pores in the peat soil are reduced, and when the pores are reduced, the peat soil becomes denser. The value of Si (Silica) also decreased from 30.01% to 21.21%. This occurred because silica reacted with lime. After all, silica is an adhesive that binds lime, making the granules denser. Peat soil’s Fe (Ferrum) value was 3.12%, then increased to 16.72%. This also helped the soil to become stronger because of the higher specific gravity of iron. Peat soil’s Al (aluminium) value was 12.15% after being given a mixture of iron oxide and cement increased to 12.16%.

Fate of nitrogen in a tropical peat soil treated with clinoptilolite zeolite

Crop productivity on tropical peat soils is poor partly because of their nutrient deficiency and the acidic nature of tropical peat soils. Ammonium (NH4+) and nitrate (NO3–) ions are commonly leached from tropical peat soils principally because of high rainfall and lack of clay to retain these nutrients. Leaching of these ions into water bodies causes water pollution through eutrophication which has been implicated in disrupting productive aquatic life. To reverse this act of environmental quality degradation, clinoptilolite zeolite (CZ) could be used to retain nutrients including NH4+ and NO3– in tropical peat soils for crop use because of the alkalinity and high affinity of CZ for retention of macronutrients. Moreover, this approach could be used as an innovative and sustainable alternative for high use of lime (CaCO3) because of the liming effect of CZ. However, information on using CZ on tropical peat soils is scarcely explored. Thus, CZ was tested in a leaching study to determine its effects on soil total nitrogen (N), exchangeable ammonium, and nitrate retention in a tropical peat soil. Treatments evaluated were: (i) soil only, (ii) nitrogen, phosphorus, potassium (NPK) fertilizer alone, and (iii) combination of different amounts of clinoptilolite zeolite (25%, 50%, 75%, and 100%) and different amounts of NPK fertilizer (50%, 75%, and 100%). The peat soils with CZ improved soil pH, exchangeable NH4+, and available NO3–. The mixture of CZ and NPK fertilizer reduced NH4+ and NO3– loss because CZ has high affinity for NH4+ whereas NO3– was absorbed into the channels of CZ. Co-application of 100% CZ with 100%, 75%, and 50% NPK fertilizer, together with 75%, 50%, and 25% CZ with 100% fertilizer increased total N of the peat soil. Ability of CZ to buffer the soil pH reduces the need for liming. This alternative way of retaining N in tropical peat soils is practical and a sustainable approach for improving peat soil productivity.

Effects of Liquid Organic and NPK Fertilizers on the Nutrient composition of Grass Jelly (Premna oblongifolia Merr) in Tropical Peat Soil

Peat soil is deficient in nutrients and agricultural development in this type of low in fertility soil is very difficult. Grass jelly (Premna oblongifolia) is a dark green shrub-like medicinal plant that has been widely used for its nutritional and medicinal properties. This study aimed to evaluate the effect of foliar application of organic fertilizers and NPK on the growth, nutrient absorption, and flavonoid content of grass jelly plants grown in peat soil. The study was carried out in a completely randomized factorial design with two factors including liquid organic fertilizer and NPK inorganic fertilizers. Three doses of liquid organic fertilizer consisting of P0 (without liquid organic fertilizer), P1 (Agrobost), and P2 (Nasa), and three levels of NPK fertilizer consisting of N0 (0g NPK polybag-1), N1 (1 g NPK polybag-1), and N2 (2 g NPK polybag-1). The results of the study revealed a nonsignificant interaction between liquid organic fertilizer and NPK fertilizer in terms of leaf growth, leaf area, fresh weight, and flavonoid of grass jelly plant growth. Further, in the case of plant nutrient contents, combined application of Nasa liquid organic fertilizer and 2 g polybag-1 NPK fertilizer tends to increase the nutrient content of N, P, and K and have the highest impact as compared to other treatments. The results of the study can be concluded that administration of liquid organic fertilizer and NPK did not affect the plant growth characteristics of grass jelly plants while in the case of nutrient content except flavonoids the level of N, P, and K of plant leaves increased.

Improving Nitrogen Availability and Ananas comosus L. Merr var. Moris Productivity in a Tropical Peat Soil Using Clinoptilolite Zeolite

Pineapple cultivation in nitrogen deficient and acidic peat soils leads to poor growth, yield, and fruit quality of pineapples. A study was conducted to determine whether clinoptilolite zeolite (CZ) could improve soil nitrogen availability, growth, yield, and fruit quality of pineapples grown in drained peat soils. Laboratory leaching experiments were conducted to determine the effectiveness of CZ in controlling nitrogen loss from peat soils, whereas an ion-exchange resin method was used to determine nitrogen availability in pineapple cultivation. Treatments evaluated were: (i) different amounts of CZ (25, 50, 70, and 100%) + NPK fertilizer, (ii) NPK fertilizer, and (iii) peat soil only. The peat soils with CZ reduced ammonium and nitrate losses because of the sorption of ammonium within the lattices of the CZ via ion exchange. Co-application of CZ (25%) and NPK fertilizers was more effective in increasing soil ammonium availability, whereas the use of CZ (25% to 100%) improved nitrogen uptake and use efficiency, growth, yield, and fruit quality of pineapple because CZ could regulate the availability of nitrogen ions for pineapple uptake. The buffering capacity of CZ increased soil pH and facilitated organic nitrogen mineralization. The co-application of CZ and NPK fertilizers can be used to improve nitrogen availability and pineapple productivity in tropical peat soils.

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 that denitrification in tropical peat soils is not a purely biological process but rather a 'mosaic' of abiotic and biotic reduction reactions. We predict that hydrological and temperature fluctuations differentially affect abiotic and biotic drivers and further contribute to the high N2O flux variation in the region.

Destabilization of carbon in tropical peatlands by enhanced weathering

Enhanced weathering is a carbon dioxide (CO2) removal strategy that accelerates the CO2 uptake and removal from the atmosphere by weathering via the dispersion of rock powder. Warm and humid conditions enhance weathering and among the suggested target areas for enhanced weathering are tropical peatlands. However, the effect of enhanced weathering on peatland carbon stocks is poorly understood. Here, we present estimates for the response of CO2 emissions from tropical peat soils, rivers and coastal waters to changing soil acidity induced by enhanced weathering application. We estimate that the potential carbon uptake associated with enhanced weathering is reduced by 18–60% by land-based re-emission of CO2 and is potentially offset completely by emissions from coastal waters. Our findings suggest that in contrast to the desired impact, enhanced weathering may destabilize the natural carbon cycle in tropical peatlands that act as important carbon sinks and protect against coastal erosion.

Identifying the Underlying Factors and Variables Governing Macronutrients in Cultivated Tropical Peatland Using Regression Tree Approach

The capability of machine learning/ML algorithms to analyze the effect of human and environmental factors and variables in controlling soil nutrients has been profoundly studied over the last decades. Unfortunately, ML utilization to estimate macronutrients and their governing factors in cultivated tropical peat soil are extremely scarce. In this study, we trained regression tree/RT, ML-based pedotransfer models to predict total N, P, and K in peat soils based on oil palm/OP and OP+bush datasets. Our results indicated that the dataset might contain outliers, non-linear relationships, and heteroscedasticity, allowing RT-based models to perform better compared to multiple linear regression/MLR models (as a benchmark) in estimating total N and P in both datasets, contrastingly, not in K. The difference of important variables in each RT-based model partially showed the vital role of land use in nutrient modeling in peat. The depth of sample collection, organic C, and ash content became the prominent factor and variables in regulating the entire predicted nutrients. Meanwhile, the distance from the oil palm tree and pH were the salient features of total P prediction models in OP and OP+bush sites, respectively. This study proposed employing ML-based pedotransfer models in analyzing and interpreting complex tropical peat data as an alternative to linear-based regression. Our initial study also shed more light on the development possibility of the pedotransfer models that agricultural practician, researchers, companies, and farmers can use to predict macronutrients, both in tabular and spatial terms, in cultivated tropical peatlands

Discussion of “Physio-Chemical Properties, Consolidation, and Stabilization of Tropical Peat Soil Using Traditional Soil Additives — A State of the Art Literature Review” by Afnan Ahmada, Muslich Hartadi Sutantoa, Mohammed Ali Mohammed Al-Bareda, Indra Sati Hamonangan Harahapa, Seyed Vahid Alavi Nezhad Khalil Abada, Mudassir Ali Khana

This discussion article provides commenting on the sections of the review paper by Ahmad et al. (the authors) concerning consistency limits determinations for peats and peaty soils, drawing on the writer's experiences regarding the usefulness of liquid limit (LL) and plastic limit (PL) testing/results for these soils in explaining their geotechnical behaviors/properties. From the writer's experience, despite being regularly specified in geotechnical engineering practice and used in research work, the conventional consistency limits tests generally do not produce physically meaningful results when testing peat soils, especially for more fibrous peats. Hence, the writer does not agree with the authors' recommendations on consistency limits testing of peats; namely, they recommended that an utmost effort is needed to improve the quality and standard of the thread rolling test and the fall-cone test for consistency limits determinations of highly organic soils such as peat. Rather than grappling with various known inherent shortcomings of consistency limits testing for peats and other highly organic soils, a suggested way forward for assessing the likely geoengineering behavior/properties of these materials points to the routine measurement of a more useful suite of index tests; namely, their natural water content, organic content, fiber content, and humification (decomposition) level. In this discussion, the above aspects are explored in detail, including greater elaboration of the writer's earlier research work in this area, which was touched on in the authors' paper.

Physical Properties of Undisturbed Tropical Peat Soil at Pekan District, Pahang, West Malaysia

Peat soilare considered soft soilwith havingweakcharacteristicssuch as low shear strength, high moisture content, and compressibility. Construction perspective, peat soilis consideredas unstable soil due to its poor engineering properties. It may cause an extensive loss in road orbuilding construction projects. Thekey objectives of the current study areto examinethe physical properties of peat soil including shear strength, liquidlimit, moisturecontent, organic content, pH, and dry densityof peat soil inPekandistrict.The peatsamples were collected fromKampung Bahru(KB), Kampung Lancing I(KLI), and Kampung LancingII (KL II), Pekan District, Pahang, Malaysia. Thefinding indicates that the shear strength (kPa) for was measured in between 7.2 to 8.2 kPa. The water content was recorded 537.10%to635.28%. The liquid limit was examined 137.638%to 152.540 %, themaximum drydensity wasexamined6.68 x 10-7kg/cm3to 7.99x 10-7kg/cm3. Theaverage organic content was calculated as approximately 95.88 % to98.48 %. In comparisonwith previous study,its indicatedthat the investigatedpeat soil in Pekan area is mainlycontent with lower shearstrength, highwater content, liquid limit, and low density, resulting in low strengthening properties. Based on the examined physical properties, its specifiedthat peat did not have adequate stability as a road or building foundation.Strengthenof peat are highlyrecommendedfor any types of construction onpeatlandin Pekan district, Pahang, Malaysia.

Shear Wave Velocity Measurements in Tropical Peat Using In-house Device

Many people in the construction industry will agree that peat is a problematic material due to its compressibility behaviour. However, construction on these areas are inevitable because of the scarcity in space and suitable land for development. Hence, there is a need for proper in-situ testing on soil properties before any construction work can be carried out in peat. Shear wave (S-wave) velocity (Vs ) used to compute the small strain shear modulus, (Go ) which is an essential parameter to design structures in earthquake and vibration prone areas. The most versatile method to assess is by measuring shear wave propagation through soil samples using bender elements tests (BET). Currently, BET is limited to laboratory environments, which can be time consuming and expensive. Therefore, a portable device of BET for peat has been proposed in this research which is simple to use and economical. The proposed setup consists of an oscilloscope, digital multimeter, signal generator, signal amplifier, direct current generator and a pair of piezoelectric bender elements. Peak-to-peak method from time domain (TD) technique is implemented as the method to analyse shear waves. To validate the function of the proposed device, different types of soil samples including Ottawa sand, Kaolin S300, Silty loam, Hemic, and Fibric peat were prepared. The peat samples for this study were collected from Pekan and Maran districts in Pahang, Malaysia. With a suitable frequency input from the sine wave generated, the Vs determined from the device was used to compute Go. Results show there is only a less than 10% error in when it was compared with the typical values of tropical peat. The proposed device is also effective to differentiate the type of soil sample when tested. In summary, the proposed in-house device can be used as an indicator and to find out the initial value of Vs and Go in tropical peat soil.

The priming effect in compost amelioration of tropical peat soil

Utilization of peat land for agriculture in Indonesia is increasing and some efforts in improving the peat soil fertility is being highly concerned. In addition to fertilizers, farmers add some fresher organic matter as the ameliorants, such as compost to support better microbial growth in the soil for increasing the decomposition process. Theoretically the addition of compost onto peat soil would lead to priming effect, hence it would accelerate the decomposition of peat organic matter. This study was to observe the impact of decomposition process due to adding compost to respiratory CO2 of peat soil. Peat soil from Central Kalimantan was used for experiment, incubated with KOH and then the respiratory CO2 was measured with titration method. Two different sizes of peat soil materials obtained from sieving peat soils, i.e. 5 mm and > the 5 mm. Each peat soil materials were mixed with 10%, 25%, and 50% compost to the total 100 grams. Post the compost addition, the samples were incubated for 20 days, and the respiratory CO2 was gauged for 4 times at 5 days interval during the incubation. It was showed that the more compost mixed to the peat soil materials, the more CO2 produced. The highest CO2 was 912.00 mg/g/day from compost incubation and a mixture of 50 gram of compost and coarse peat soil material produced 460.8 mg/g/day.