Abstract
In this paper, the pathway from peat resources to their various forms of utilization, to their environmental impacts, and to their mitigation is discussed. Overall, research gaps related to various fields of peat studies are identified and recommendations for future research are presented. Global peat reserves are large, but they remain mostly unused. Peat can also be valorized in various less GHG–intensive applications beyond combustion. Heterogenocity of peat may constraint many of these uses, warranting new innovations to support their feasibility. The theme of GHG emissions from peatlands is complex. The future of northern peatlands as carbon sinks remains uncertain. Paludiculture, an emerging research field, and its GHG mitigation potential is also discussed. When discussing peat production, one of its main adverse effects typically disclosed is its impact on the water quality of natural aquatic systems. Thus, different traditional and novel peat bog drainage water treatment methods are extensively compared with each other — a topic not previously presented in the literature. Peatland restoration and its novel applications, as well as economic aspects, are also addressed. Socioeconomic aspects of peat use, closely linked to climate, food, and rural livelihoods, are currently under vigorous research, and are also examined.
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Recent Applications of Peat Resources Utilization and Its Environmental Impacts Mitigation – A Review
Ville Kuokkanen,a,* Matti Kuokkanen,b and Hanna Prokkola 
c
In this paper, the pathway from peat resources to their various forms of utilization, to their environmental impacts, and to their mitigation is discussed. Overall, research gaps related to various fields of peat studies are identified and recommendations for future research are presented. Global peat reserves are large, but they remain mostly unused. Peat can also be valorized in various less GHG–intensive applications beyond combustion. Heterogenocity of peat may constraint many of these uses, warranting new innovations to support their feasibility. The theme of GHG emissions from peatlands is complex. The future of northern peatlands as carbon sinks remains uncertain. Paludiculture, an emerging research field, and its GHG mitigation potential is also discussed. When discussing peat production, one of its main adverse effects typically disclosed is its impact on the water quality of natural aquatic systems. Thus, different traditional and novel peat bog drainage water treatment methods are extensively compared with each other — a topic not previously presented in the literature. Peatland restoration and its novel applications, as well as economic aspects, are also addressed. Socioeconomic aspects of peat use, closely linked to climate, food, and rural livelihoods, are currently under vigorous research, and are also examined.
DOI: 10.15376/biores.21.2.Kuokkanen
Keywords: Peat; Peat utilization; Peat refining; Peatland restoration; Peat water treatment; Environmental impacts; Paludiculture; Socio-economic impacts
Contact information: a: Biobros Ltd, Telkkistentie 2, 70460 Kuopio, Finland; b: MFibrils Ltd, Onnelanpolku 1A, 80400 Ylämylly, Finland; c: University of Oulu, Research Unit of Sustainable Chemistry, P.O. Box 3000, 90014 Oulu, Finland; *Corresponding author: villekuok@gmail.com
INTRODUCTION
A mire is an ecosystem with a high groundwater level, where organic material accumulates and forms peat through the slow biodegradation of wetland plants under anaerobic conditions (International Peatland Society 2025). Peat formation is a process that takes several thousand years (Loisel and Gallego-Sala 2022). It precedes the formation of fossil fuels (Nadon 1998). The reaction sequence that precedes the formation of coal from peat is known as coalification—a geological process in which organic material is transformed into coal. During the biological stage, peat is formed, which gradually transforms into coal under the influence of relatively high temperatures and significant pressure. The formation of coal is further enhanced by geological time and tectonism (Marsh and Rodríguez-Reinoso 2006; Flores 2014). The degree of maturation reached during the hardening process of organic material increases gradually and can be determined based on the measured C/H ratio, as well as the residual concentrations of oxygen, sulfur, and nitrogen (Marsh and Rodríguez-Reinoso 2006).
Peat biodegradation refers to the decomposing of plant residues, resulting in the formation of humic substances. This reaction is influenced by temperature, pH, and moisture conditions. The degree of peat biodegradability indicates the environmental conditions under which it was formed. (Drzymulska 2016). Main contents of anaerobic biodegradation reactions are 50 to 70% methane (CH4) by volume, 30 to 50% carbon dioxide (CO2), and traces of other gases (Jameel et al. 2024). Peatlands are typically under anaerobic conditions, although the hydrological dynamics of the upper layer of peat (the acrotelm) are directly related to fluctuations in the water table. Thus, the acrotelm is not always saturated (Holden and Burt 2003).
Since peat is generally classified as a non-renewable fuel (although theoretically it is slowly renewable), comparing its emissions to those of other biomass sources is problematic, especially because it affects its sustainability status (economic and ecological implications) (Vainio et al. 2024). Regarding this, rates of peat formation are controlled by a combination of climatic (temperature, moisture), hydrological (water-table depth) and vegetation/ peatland-specific factors (Fenton 1980; Omar et al. 2022; Swindles et al. 2025). Tropical high temperatures favour organic matter decay, but high moisture content promotes peat formation from plant remnants. Tropical peatlands generally accumulate peat at a rate of 1 to 5 mm/a (and up to 10 mm/a), a rate much higher than that of boreal and subarctic peatlands (Omar et al. 2022).
Fenton (1980) studied three Antarctic moss banks in detail — two of which were dominated by Polytrichum alpestre and one by Chorisodontium aciphyllum — finding a moss bank growth rate of 0.9 to 1.3 mm/a. In a recent study by Swindles et al. (2025), apparent peat accumulation rates over the last two millennia in 28 well-dated European peatlands ranged between 0.05 to 4.48 mm/a (mean 1.18 cm/a), supporting the common estimate of ~1 mm/a. Highest rates occurred in Scandinavia and the Baltic, lower in Britain, Ireland, and Continental Europe. Summer temperature significantly controlled peat accumulation, and higher rates are often linked to wetter conditions inferred from water-table depth.
Peatlands function as carbon sinks in much the same way as forests where trees grow. Mires must be drained before they can be used for peat extraction, which has socio-economic impacts, and also introduces environmental risks—some of which can be managed through legislative changes. In this essence, protection of natural water bodies is a key aspect that needs to be taken into account. As a matter of fact, when peat production is discussed, one of its main adverse effects typically disclosed is its impact on the water quality of natural aquatic systems. Thus, more effective solutions for treatment of peat water should be developed (or the operation of current methods enhanced). It should also be noted that the human-centered exploitation of bogs has led to their large-scale degradation. For example, 25% of Europe’s peatlands are degraded, and within the EU the share is around 50% (≈ 120,000 km²); degradation increases from north to south (Tanneberger et al. 2021). Therefore, recommissioning and protecting them is important, taking into account the related costs. Peat also has multiple uses (typically producing less CO2) beyond combustion, which are discussed in this article.
The aim of this paper is to provide broad insights into recent applications of peat resources and the mitigation of environmental impacts. Socioeconomic aspects of peat utilization are also discussed. Research gaps are identified and recommendations for future research are presented. To the best of our knowledge, no recent comprehensive review has been published that covers all the thematic areas presented in this article. Particularly papers with a similar framework (from peat resources to their various forms of utilization, to their environmental impacts, and to their mitigation) have been missing.
CHEMICAL CHARACTERIZATION OF PEAT
Factors influencing peat formation and properties include climatic conditions, as well as geological, geomorphological, and hydrological factors (Hu and Ma 2002). The moisture content of dead plants strongly affects the quality of organic matter present in peat. Under moist conditions, microbes convert non-humic substances such as hemicellulose, cellulose, lignin, pectin, bitumen, waxes, resins, nitrogen-rich materials, lipids, amino acids, unsaturated and saturated fatty acids, various types of starch carbohydrates, oils, organic sulfur compounds, balsams, bioterpenes, and tannic acids into stable humic substances (Trckova et al. 2005). The formed humic substances, e.g. humic, fulvic, ulmic acids, and humins, make up the majority of the partially decomposed peat (Kocabagli et al. 2002; Janos 2003; Perminova et al. 2003). Peat compresses well, and its moisture content is high, while its shear strength is low, and it has low load-bearing capacity (Zainorabidin and Wijeyesekera 2007; Zainorabidin et al. 2007).
The same metals and non-metals found in the surrounding soil are also present in peat. Nearly all (about 90%) of the total elements found in peat ash consist of Si, Al, Fe, Ca, Mg, Na, and P (Hu and Ma 2002). These elements are also found in rainwater, along with e.g. K and Ti. The original pH of peat is around 3.3 to 3.8 (Rahman and Ming 2015). According to Rezanezhad et al. (2016), peat decomposition is widely assessed using the von Post scale (H1 = least, H10 = most decomposed). Changes in peat composition with age are presented in Table 1.
Peat is classified into three main types. The first is fibrous peat, which is slightly decomposed and still has a recognizable plant structure. Hemic or semi-fibrous peat has a moderate degree of decomposition. The most decomposed peat, which is located at the bottom of the bog, is saprine or amorphous peat, which no longer has a recognizable plant structure (Gowthaman et al. 2022). Of these, surface peat (fibrous peat) is used for purposes other than generating electricity and heat, for which the well-decayed bottom peat is used (Arvola 2015).
Table 1. Changes in Peat Composition with Age (adapted from Arvola 2015)
An accurate understanding of lignocellulosic biomass composition is crucial, when its valorisation (especially chemical production) is targeted. On a dry basis, biomass (e.g., energy crops, grasses, softwood, hardwood, and various secondary streams) typically consists of 35 to 51% cellulose, 20 to 33% hemicelluloses, and 13 to 30% lignin. Furthermore, there is variance in the proportions of these components between different types and subtypes of lignocellulosic biomass (Segers et al. 2024).
GLOBAL PEAT RESERVES
Most of the global carbon resources are located in mires, with an estimated 500 ± 100 Gt C in northern peatlands. Northern peatlands cover an area of approximately 3.2 million km² (Loisel et al. 2017). Mires occur in all climate zones and continents, covering a total area of 4.23 million km², corresponding to 2.84% of the Earth’s surface (Xu et al. 2018). This is also visible in Fig. 1, in which global peat distribution is presented. Peatlands sequester twice more carbon than all the world’s forests combined (Dunn and Freeman 2011). Boreal and subarctic mires are found over large areas with abundant soil carbon reserves, as frozen and thawing peat. The major global peatland complexes are located in in the circum-arctic zone, with Western Siberian Lowlands (Russia), and the Hudson and James Bay Lowlands (Canada) containing a particularly high area of peatland (Xu et al. (2018).
Peatlands are found (Fig. 1) across over 180 countries (Parish et al. 2008). The distribution of peatlands varies depending on different environmental conditions. The largest peatland areas are in Canada (1.13 million km2) and Russia (1.37 million km2) (Xu et al. 2018). Peat growths occurs in rather wet conditions in the Nordic countries, because the winters at high latitudes are long (with snow-cover), whereas temperatures are moderate in the summer. Peatlands cover vast areas in the Nordic countries, including 66,680 km² in Sweden, 94,000 km² in Finland, and about 23,700 km² in Norway (Nordic Joint Committee for Agricultural Research 2008) Other areas with significant peatlands are located (Fig. 1) near to the equator (e.g., the peat wetlands or swamp forests in Indonesia, Amazon, and the Congo Basin) (Xu et al. 2018).
Fig. 1. The Global peatland Map 2.0 (Adapted from United Nations Environment Programme 2021).
UTILIZATION OF PEAT
Peat may be combusted for energy. However, in recent history, peat has played a significant role in national energy mixes mainly in a few countries, particularly Finland and Ireland, but its importance has declined markedly in recent years (Lempinen and Vainio 2023). In addition to combustion, peat has many different applications, some of which may be challenging to replace with other materials. Figure 2 shows a diagram of the global distribution of different forms of peat usage.
Fig. 2. Global peatland utilization area distribution (World Energy Council 2013; Clarke and Rieley 2010)
For many purposes, rapidly renewable peat from the less decomposed surface layer is used (Arvola 2015). In Finland, approximately 1.5 to 3 million cubic meters of peat are used for these purposes annually (Bioenergia ry 2024). In Finland and the Nordic countries, peatlands have been extensively utilized for energy production and forestry. Nevertheless, this is not significantly reflected in Fig. 2, as the peatland area in these countries is relatively small compared to the global total peatland area. Surface peat can be used as a growing medium, for absorbing urine and manure, for absorbing solvents and oil in both land and water areas; at a certain moisture content, peat becomes hydrophobic and begins to repel water. It can also be used as an oil spill adsorbent, a composting aid, for the purification of liquids and gases, in landfill capping, as a filler and reinforcing material, as a raw material for textiles (spun or felted into wool or silk) as well as for spa and therapeutic peat (Leinonen 2010; Perdana et al. 2017; Bioenergia ry 2024). In Finland, the main applications of peat are as bedding material in livestock farming, as a growing medium, and in landscaping and green area maintenance, and relatively small amounts are used for other purposes (Bioenergia ry 2024).
In addition, separating peat into fractions and using them can be a viable solution, for example, in the production of plastic composites. Favorable properties of peat in terms of mechanical processing are: fibrous, easy to grind, hydrophobic, antiseptic, adsorption/absorption capacity, cheap (Arvola 2015). Various possibilities for peat usage have been presented in Fig. 3. Some of the peat applications presented in Fig. 3 are in real-world use, while others are still more on the level of ideas and need more research to support the feasibility of producing/using them in the given application. According to Arvola (2015), peat composites have great potential, and peat products such as insulation and acoustic boards are already produced. Environmental peat, such as growing media and bedding materials, are also well-known products, as discussed earlier. To the best of our knowledge, chemical modification, thermochemical processing and chemical fractionation products with peat remain mainly of academic interest and have been studied less, mostly because of constraints in technical (e.g. high moisture content) and economic feasibility of such products, also as indicated by Arvola (2015). Combustion is the main utilization method for peat.
Fig. 3. Refining of peat and bog biomass. Adapted from Arvola (2015).
On the whole, to enhance real-world usability of peat refining pathways presented in Fig. 3, further investigation and new innovations are encouraged. When exploring new possibilities for peat valorization, it is important to consider what can be produced, at what cost, and its value to the user. Existing alternatives and what the new product would replace should be assessed, along with technological readiness, potential need for new technology, and related development and investment costs. Previous studies and their outcomes should be reviewed, key stakeholders identified, and the idea evaluated for political, economic, social, technological, environmental, and legal feasibility (Arvola 2015). The use of finely ground peat and Sphagnum moss would be technically (and likely also economically) feasible in polymer composites, particularly in polyurethanes, as functional filler materials (Koivuranta et al. 2017; Ämmälä and Piltonen 2019). However, further research on the subject is warranted.
A recent review discussed the varying lignocellulosic biomass valorisation pathways currently utilized or under development. These include variations in biomass composition, possible end-products, pretreatments, and conversion methods. Each valorisation pathway was found to have its own implications and potential. The process was found to be complex due to high multi-factor dependency. Optimal routes were not identified for linking biomass sources to end-products (Segers et al. 2024).
Many other biomasses are often considered rather homogenous compared to peat. Humic materials and inorganic substances contained in peat complicate direct industrial refining and value-adding chemical production. This makes the value-creation processes for other lignocellulosic biomasses more efficient and easier to optimize than for peat.
Use as Bedding Material and Nutritional Supplement
Certain properties of peat moss advocate its potential suitability for use in the poultry industry. Its efficient moisture management abilities (quick absorption and release of excess moisture) are beneficial in poultry houses. The natural pH value of peat is low (3.0 to 4.0) (Lee et al. 2021). Peat is beneficial in controlling ammonia and reducing bacterial populations in the bedding material. Peat moss can absorb water almost 8 times its own weight, while chopped wheat straw can absorb about 7 times its own weight (Shepherd et al. 2017). Peat can also absorb about 30 g NH3/[kg dry peat] (Abbès et al. 1993). One study evaluated four different bedding types for cattle (long straw, chopped straw or without additives, and chopped straw/peat mix), and according to the report, emissions were lowest with the chopped straw/peat mix (Misselbrook and Powell 2005). The poultry industry uses bedding materials such as sawdust, rice husks, sugarcane pulp, bagasse, chopped straw, paper mill by-products, sand, wood shavings, corn cobs, oat hulls, dried leaves, and coffee bean husks (Toghyani et al. 2010; Ramadan et al. 2013).
In one of the few studies comparing peat to wood shavings, peat bedding was found to be healthier for broiler footpads (de Baere et al. 2009). A large Danish study (Kyvsgaard et al. 2013), on the other hand, found that differences in footpad condition didn’t differ much when using wood shavings and peat. However, footpad condition was found worse when straw litter was used.
The stable’s air quality, as well as management and composting of manure, may be enhanced with proper selection of bedding material with specific beneficial qualities. In a comparative study of bedding materials, wood chips, straw, peat, hemp, flax, sawdust, shredded newspaper, and various mixtures—peat/wood chips, peat/sawdust, and peat/straw—were used. Peat and peat-based mixtures showed the best performance in absorbing ammonia, water holding capacity (retention), and fertilizing ability of manure. Straw, flax, hemp, and peat were found to contain higher amount of fungi and bacteria than newspaper and wood-based materials (Airaksinen et al. 2001).
Poultry house litter contains nutrients, which are essential for plant growth (N, P, K, S, Ca, Mg, B, Cu, Fe, Mn, Mo, and Zn), proposing its use as an excellent fertilizer (Subramanian and Gupta 2006). Using peat as a feed supplement has increased, and peat products are commercially available. This is particularly due to peat’s growth-stimulating ability in piglets and sows, as wells as its ability to prevent enteric diseases in them. Indeed, because peat contains biologically active substances and is readily available, in addition to agriculture, it has also been used in human and animal medicine (Trckova et al. 2005).
Combustion and Use as a Chemical Precursor
Prior to combustion, peat must be dried. This may be done either by solar drying on the open fields of bogs, or by using various industrial drying methods. Before drying, peat may contain up to 95% water, whereas typically drained bogs have a moisture content of 89 to 91%. Three commercial peat types are commonly presented: milled peat (moisture content of 40 to 50 percent), air-dried sod peat (moisture content of 30 to 40 percent) and artificially dried compressed peat briquettes (moisture content of 10 to 20 percent). Large-scale mechanized extractions of dried peat are typically used to produce milled peat. The effective calorific value of milled peat at operating moisture content is about 10,5 MJ/kg. Sod peat and peat briquettes are produced on a smaller scale, applying either dry or wet conditions and manual, semi-mechanical, or mechanical methods. (Andriesse 1988).
Wood material contains more potassium and sodium than peat. Soluble alkaline substances are released into the gas phase during combustion, causing corrosion of the combustion pipes. Chlorine-containing ash causes hot corrosion of heat transfer surfaces. Peat can be used for co-combustion with wood at a ratio of about 10 to 20%. If these combustible wood materials mainly consist of logging residues, a higher proportion (30 to 40%) of peat is recommended (Orjala et al. 2004). Peat, coal, and municipal wastewater sludge are suitable for co-combustion with biomass, because they help prevent corrosion (Kassman et al. 2011). The protective effect of peat is primarily due to sulfur and, to some extent, aluminosilicates – both can remove alkaline chlorides (mainly KCl) (Aho 2012):
SO3 +2 KCl + H2O → K2SO4 + 2 HCl (1)
Al2O3 * 2 SiO2 + 2 KCl + H2O → K2O * Al2O3 *2 SiO2 + 2 HCl (2)
Lundholm et al. (2005) demonstrated that all peat fuels prevented agglomeration in the studied range of 760 to 1020 °C, and even with 5% peat fuel, significant effects were observed. The results also indicated that the mechanism for preventing agglomeration of bed material varies between different peat fuels. Possible mechanisms include peat minerals trapping alkalis, e.g., calcium raising the melting temperature, and sulfur reacting with alkali metals to prevent agglomeration by increasing the melting point and reducing viscosity.
Peat ash contains plant nutrients, e.g., phosphorus, making it a potential fertilizer in forestry. For example, previously, Finland’s energy production generated 300,000 to 400,000 tonnes of peat and mixed peat-wood ash annually (Moilanen et al. 2012). However, peat energy use in Finland has halved from about 16 terawatt h (TWh) in the last decade, also reducing peat ash production (Bioenergia ry 2024). Compared to wood ash, nutrient concentrations and liming capacity of peat ash are low; nitrogen is mostly lost during combustion and nearly absent in well-burned ash (Hytönen 1998).
Fischer-Tropsch (F-T) diesel is produced from the syngas generated by peat gasification using the F-T synthesis to produce hydrocarbons for combustion. The production chain involves several stages that must be considered: peat extraction, production, transportation, gasification, refining into F-T diesel, storage and distribution, and conversion into mechanical work (Kirkinen et al. 2007b).
In the F-T process, which is a catalytic chemical reaction, gasification-derived syngas (containing carbon monoxide (CO) and hydrogen (H2)) is converted into various hydrocarbons with different molecular weights, according to the following equation (Darmawan and Aziz 2022).
(2n+1) H2 + n CO → Cn H(2n+2) + n H2O (3)
In addition to F-T diesel production, peat can be chemically or thermochemically refined into various other products (Arvola 2015). A conceptual diagram of various known chemical engineering processes that can be used to refine peat into new products is presented in Fig. 4.
Fig. 4. Various chemical processes for refining peat into new products. Adapted from Arvola (2015)
Greenhouse Effects
Combustion of peat produces carbon dioxide. Along with CO2, peat production and harvesting also produces methane and other greenhouse gases (GHGs). On the other hand, in the course of photosynthesis, plants produce sugar and oxygen from water and carbon dioxide, using sunlight for carbon-capturing from the atmosphere. The carbon-compounds formed this way are mostly stored in the soil. When discussing peat utilization, it should be taken into account that peat’s biodegradation releases methane on-site (Kirkinen et al. 2007a). This biodegradation is anaerobic, as discussed earlier. The production of biofuels can also alter the ecosystem’s long-term carbon storage, thus impacting the carbon footprint of energy production (Kirkinen et al. 2008). The extraction of peat for combustion affects GHG emissions from peatlands, especially methane emissions (Kirkinen et al. 2007a).
Recent studies show that approximately 1100 to 1500 Pg of organic carbon is contained in the northern permafrost regions, of which about 500 Pg is seasonally thawed, while approximately 800 Pg remains permanently frozen (Hugelius et al. 2014). Around 20 to 60% of the organic carbon in permafrost is stored in peat (Schuur et al. 2008). In the laboratory incubation studies of Turetsky (2004), it was found that peat from thawing permafrost regions emitted substantially more GHGs than peat from frozen permafrost under similar conditions. This indicated that permafrost-driven changes in peat quality have an impact on its decomposition rate (Turetsky 2004). Approximately 15% of peatlands have been drained and deforested worldwide, with the main reason being commercial agricultural use, resulting in 1.3 Gt CO2/yr emissions, not considering the significant emissions originating from peat fires (Mishra et al. 2016). However, a general estimate of global annual anthropogenic CO2 emissions is 40 Gt. Turetsky (2004) suggested that permafrost patterning (including the thaw of permafrost decades or centuries in the past) has important influences on soil chemistry, with feedbacks to ecosystem processes such as decomposition.
As a consequence of climate change, a potential future risk in need of more discussion and research is the increasing vulnerability of some peat bogs to fires, which will be hard to put out. Such fires ignite more easily than flaming combustion. They are dominated by smoldering combustion, which may also persist in wet conditions. Climate change and human-induced drying are lowering the water table in peatlands and increasing the frequency and severity of peat fires. Burning of deep peat layers affects older soil carbon that has not participated in the active carbon cycle for centuries or even millennia, and thus determines the importance of peat fire-induced emissions to the carbon cycle and climate feedbacks (Turetsky et al. 2015). Lin et al. (2021) estimated that at a boreal region warming rate of 0.44°C/decade, the amount of carbon lost due to boreal peat fires in warmer soil could increase from 143 Mt (in 2015) to 544 Mt (in 2100), reaching a total of 28 Gt in the next century.
Peatland Climate Modelling
Peatlands have played an important role in the GHG composition in the atmosphere for most of the Holocene, leading to an estimated net cooling of ∼0.5 W/m2 (Frolking and Roulet 2007). Northern peatlands began developing ∼16.5 thousand years ago, expanded rapidly between 12 and 8 thousand years ago due to high summer sunlight and rising temperatures, and contributed to early Holocene CH₄ peaks and modest CO₂ declines. They also likely influenced CH₄ and CO₂ fluctuations during earlier warm and cool periods (MacDonald et al. 2006). Even though peatlands have likely influenced Holocene climate, their role has only recently been included in climate assessments (Frolking et al. 2010). Earlier on, only a few studies had incorporated peatland carbon sinks into Holocene climate models, with limited or no climate-peatland feedbacks. However, many recent studies (Zhuang et al. 2020; Zhao and Zhuang 2023; Zhu et al. 2025) have added these feedbacks into the models applied in them.
Current policies make overshooting (climate change pathways where global temperatures temporarily exceed a target) the 1.5 °C temperature goal of the Paris agreement likely. Since northern peatlands are vast carbon storages and are warming faster than the global average, there is a risk for them to accelerate climate change by releasing more carbon into the atmosphere. Global warming causes peatlands’ net carbon uptake to increase, but higher methane emissions largely offset this. Peatlands have been found to decrease the remaining carbon budget by 40 GtCO2 (16 to 60 GtCO2), or 8.6%, if the 1.5°C temperature goal is exceeded. Thus, this emphasizes the importance of better incorporating peatlands into climate models (particularly those concerning overshoot scenarios) to assist improving future political decisions (Zhu et al. 2025).
The future of northern peatlands as carbon sinks is uncertain. In a recent study (Zhao and Zhuang 2023), northern peatlands were predicted to turn from sinks to sources around 2050, sooner than previously estimated (after year 2100), highlighting their vulnerability to climate change. Furthermore, according to Zhuang et al. (2020), permafrost degradation and other disturbances may increase peat decomposition and alter peatland areas, complicating sink–source assessments, despite earlier research indicating northern peatlands will remain carbon sinks this century. On the whole, the models applied in these studies need to be developed further to reduce the uncertainties related to the question of peatlands function as carbon sinks.
Peatland Restoration and Management for Greenhouse Gas Mitigation
Northern peatlands are a major but highly variable source of atmospheric methane (CH₄), and both management and restoration strongly affect CH₄ exchange with the atmosphere. A systematic review and meta-analysis (87 studies, 186 sites across northern peatlands) showed that CH₄ emissions are mainly controlled by water table depth, plant community composition, and soil pH, with the highest emissions occurring in fens. Natural northern peatlands were found to emit CH4 highly variably, with a 95% confidence interval of 7.6 to 15.7 g C m−2 year−1 for the mean and 3.3 to 6.3 g C m−2 year−1 for the median. The overall annual average was found to be (mean ± standard deviation) 12 ± 21 g C m−2 year−1. Temperature alone is a weak predictor, but its interaction with hydrology, vegetation, and soil properties is critical. Drainage significantly reduces CH₄ emissions (on average by 84%), whereas restoration through rewetting or vegetation recovery increases CH₄ emissions by about 46% compared to pre-management levels. To assess the overall climate impact of peatland management, both net ecosystem exchange and carbon exports must be considered (Abdalla et al. 2016).
A search conducted by Haddaway et al. (2014) identified over 26,000 articles, and screening of available full texts yielded 93 relevant articles (110 independent studies). 39 studies were excluded from the critical review, leaving 71 for synthesis. The results show that in boreo-temperate lowland peatland systems drainage increases N2O emissions and ecosystem CO2 respiration, but reduces CH4 emissions. Second, naturally drier peatlands emit more N2O than wetter ones. Finally, restoration was found to increase CH4 emissions.
A review paper by Kumar et al. (2020) discussed fundamentals of mitigating the major GHG emissions (CO2, CH4, and N2O) from tropical peatlands in Southeast Asia and their impact on global climate change. Also, in their study it was found that rewetting peatland may increase CH4 emissions, however stating that more research is needed to determine whether peatlands act as GHG net sinks or net sources. Only a few studies were found to have examined the effectiveness of liming in reducing peat soil acidity. Furthermore, there is a shortage of data on CO2 concentrations in drainage and forest fire areas, N2O fluxes in agricultural areas, as well as the contribution and reduction of CH4 in tropical peatlands. It was concluded that these topics warrant further research to help develop a framework for GHG emission measurements and mitigation in tropical peatland regions.
Waddington and Day (2007) observed that seasonal CH4 emissions did not differ before and immediately after peatland restoration. However, three years after restoration, seasonal CH4 emissions at the restored site were 4.6 times higher than at the peatlands prior to restoration. Ponds and ditches at the restored site were seasonal hotspots for CH4 emissions. However, the emissions from grass vegetation were the dominant source of CH4 from the restored peatland due to its large area. The CH4 fluxes from the studied peatland represented 14% of the area’s CO2 equivalent losses. This study highlights the significance of vegetation succession in the CH4 flux from peatlands.
Fertilizing low-yield wetlands can mitigate climate change over decades. The productivity gains from fertilization lead to increased forest CO2 sinks, which significantly outweigh soil CO2 net emissions. Previous research also has not found short-term rise in GHG emissions from soils in drained peatlands under forestry (Ojanen et al. 2019).
Decommissioned peatlands could be used for forestry, serving as effective carbon sinks. GHG emissions can also be diminished after production by cultivating plants like hemp on peatlands, which sequester carbon throughout the growing season. In Fig. 5, ongoing small-scale cultivation testing in former peatland in Halsua, Finland, is presented. Hemp’s growing season lasts from spring to late autumn, allowing it to be harvested and take full advantage of the entire thawed ground period. Crop rotation with hemp improves soil health and reduces pests. This is an interesting topic, demanding more research, especially related to its sosio-economic impacts as well as its application on varying locations globally.
Fig. 5. Cultivation of hemp in a former peatland (photo taken in October 2024).
Paludiculture for Greenhouse Gas Mitigation
Paludiculture, which means wetland farming where crops are grown on rewetted peatlands, is a rather new idea related to climate warming countermeasures and has recently gained global interest. According to Tan et al. (2021), the long-term effects of paludiculture should be carbon-neutral or carbon-negative. They also noted that paludiculture development is based on northern peatland research, and the subject has scarcely been researched in tropical peatlands. Thus, more research on tropical paludiculture is warranted.
Native species should be selected as vegetation sources for paludiculture (Tan et al. 2021). Various crops can be cultivated. For example, in a Latvian study (Ozola et al. 2023), paludiculture of Sphagnum spp., black alder (Alnus glutinosa), common reed (Phragmites australis), reed canary grass (Phalaris arundinacea), cattail (Typha latifolia/angustifolia), and sweet flag (Acorus calamus) were assessed and found to have promising results for upcoming large-scale implementation by private enterprises. As noted by Gaudig et al. (2014), large-scale implementation of Sphagnum farming requires extensive know-how, from initial species selection up to the final production as well as using growing media derived from Sphagnum biomass in horticulture.
An Indonesian study (Uda et al. 2020) found that among the studied crops, sago (Metroxylon sagu), banana (Musa paradisiaca), pineapple (Ananas comosus), water spinach/kangkong (Ipomoea aquatica), kelakai/edible fern (Stenochlaena palustris), illipe nut/tengkawang (Shorea spp.), dragon fruit (Hylocereus undatus), mangosteen (Garcinia mangostana), and sweet melon/melon (Cucumis melo) were found as the most suitable alternatives for local paludiculture. However, it was stated that precaution is necessary when planting crops requiring low drainage.
Myllyviita et al. (2024) studied climate change mitigation potential of paludiculture in Finland. They found that rewetting reduces emissions from drained peatlands, and paludiculture can provide renewable raw materials as an alternative to peat. Paludicrops were used instead of peat for animal bedding and growing media. Results indicated that compared to current peat use, paludiculture could save 352,000 t CO2-eq by 2050, mainly through reduced land-use emissions. Most of the paludiculture emissions came from crop cultivation (300,000 t CO2-eq), with a carbon sink of 48,000 t CO2-eq. It was suggested that paludiculture is unlikely to exceed peat-related emissions but that it does not fully offset abandoned cropland emissions, and that afforestation or restoration could yield greater savings.
A four-year experiment conducted in Finland, in which the groundwater level was raised gradually and CO₂, CH₄, and N₂O (nitrous oxide) emissions were measured. The results showed, among other things, that a 10 cm increase in water level reduced CO₂ emissions by ~0.87 Mg CO₂-C ha⁻¹ per year. CH₄ fluxes varied from uptake to emission as the water table rose. Nitrous oxide emissions ranged between 2 to 33 kg N2O-N ha−1 yr−1; emissions were initially high on bare soil but declined by the end of the experiment, likely due to more plant cover and higher water table limiting aerobic soil conditions. Overall, the area remained a net carbon source, highlighting the emission-related challenges of highly decomposed peatlands (Lång et al. 2024).
In Denmark, Nielsen et al. (2024) found that in nutrient-rich peatlands, paludicultivation can be a carbon sink right from the start, but in nutrient-poor bogs the result was the opposite. Since the results on paludiculture for GHG mitigation still seem to be variable and unclear, more research is needed on the subject. Furthermore, the effect of paludiculture on peat water quality should be studied in future, also in conjunction with novel peat water treatment technologies.
REHABILITATION OF DECOMMISSIONED PEATLANDS
Decommissioned peatlands may be rehabilitated (or restored) and used for various purposes as well as to mitigate their detrimental environmental impacts, including reducing GHG production and biodiversity promotion, or for paludiculture. Furthermore, peatland rehabilitation may help to restore ecosystems and improve water quality, leading to e.g. decreases in soil erosion. Soil amendments used for the reclamation of decommissioned peatlands generally aim to improve soil structure and optimize nutrient availability. However, these areas, where peat extraction has ceased, can be challenging for farming due to poor aeration, compaction, and weak nutrient cycling (Kuokkanen et al. 2019). Peat itself can also be used for soil improvement and cultivation.
Soil Improvers for Peatland Rehabilitation
Certain soil properties can be influenced by adding various soil amendments. These properties include water retention, aeration, temperature, nutrient retention and availability, cation exchange capacity (CEC), structure and pore stability, as well as microorganisms, insects, and pests (Shinde et al. 2019). Biochar, made from various organic materials can improve soil structure by enhancing aeration, water retention, and nutrient availability. It can also have a variable effect on the GHGs emitted by the soil (He et al. 2017). Compost and other sources of organics, e.g. manure compost, can be used to amend peat soils, resulting in an improved soil structure and increased organic matter content, acting as an enhanced basis for microbial activity as well as promoting nutrient cycling. Sand or clay can also be added to decommissioned peatlands to improve water-physical properties of the peat soil, with sand enhancing, e.g., aeration and nutrient retention, and clay improving the growing media rewetting ability (Michel 2009; Zakharova et al. 2020).
Tailored peatland fertilizers are beneficial for peatland reclamation, since they contain essential nutrients such as nitrogen (N), phosphorus (P), and potassium (K). Thus, soil growing-conditions will improve, supporting plant growth. Adding organic matter and microorganisms can enhance biological activity and promote nutrient recycling (Deru et al. 2023). Schulte and Kelling (1998) studied various soil amendments, including crop residue, manure, compost, peat, sawdust, sewage sludge, green manure, cover crops, and topsoil. Organic matter content of the soil was increased by all of the soil amendments studied. Materials with low C:N ratio (< 28:1) release nitrogen upon decomposition, while materials with high C:N ratio bind nitrogen. Plants can utilize nutrients once they are converted into inorganic forms. Additionally, soil amendments influence the soil microbial balance. Babla et al. (2022) investigated the addition of carbon to soil mixed with organic materials and found that soil amendments made from waste materials can be pelletized, allowing organic matter and nutrients such as N and K to slowly dissolve into the soil. Therefore, the physical, chemical, and biological characteristics of the soil are improved, contributing to sustainable agriculture.
A new innovation, presented in Fig. 6, suggests utilizing valuable biomasses from industrial side streams as fertilizers and soil improvers on peatlands converted to carbon sinks. Kuokkanen et al. (2019) studied the use of soil amendments in non-food potato production.
Industrial side streams and by-products can serve multiple purposes in non-food potato production. However, the common practice of monoculture in potato cultivation creates significant challenges, such as soil compaction, depletion of humic substances, and a decline in the soil’s nutrient retention capacity. These changes, in turn, lead to increased nutrient leaching, which not only reduces nutrient availability for crops but also results in economic losses and imposes additional burdens on the environment (Hansen 1996). Environmental impacts of peatland non-food potato cultivation can be minimized by using suitable soil amendments, which offer a promising solution due to their chemical purity. Soil particle bonds help plants access water and nutrients, with medium-sized pores retaining water and larger pores allowing root growth.
Coarse soils with large pores are preferred for potato cultivation, and adding biotechnologically modified fiber sludge enriched with nutrients can improve soil health and act as fertilizer (Kuokkanen et al. 2019). Biotechnologically modified fiber sludge decomposes at a slow rate and serves as a substrate (Kuokkanen et al. 2018). Previous studies have successfully tested five industrial by-products as soil amendments for decommissioned peatlands: fiber sludge, biocarbon, hygienic biodigestate, paper mill sludge and gypsum waste (Kuokkanen et al. 2019).
Fig. 6. The circular economy cycle of non-food potato production in decommissioned peatlands (Kuokkanen et al. 2019)
In the future, it would be valuable to further investigate the long-term functionality of the soil amendments described above. For example, gypsum waste takes many years to fully dissolve in the soil, whereas the properties of fiber sludge can be enhanced through enzymatic treatment and should be tested under a variety of soil conditions. In such studies, economic aspects should also be scrutinized in detail, since this kind of analysis is still lacking.
Stabilizing peatlands for construction or road building is crucial and has been highlighted in recent studies. For instance, Affam et al. (2023) studied adding of sodium, calcium and zinc compounds along with biochar to peat soil to increase its strength and stabilize the soil, finding them effective. Similarly, Vincevica-Gaile et al. (2021) suggested that the addition of limestone could improve peatland stabilization, and they also proposed the use of ash from various sources. Untreated waste, products made from recycled materials, and waste from biological treatment of municipal waste, landfills, and industrial processes can also be utilized as raw materials. Additionally, composite materials are useful for soil reinforcement, especially for road or building construction. Bamboo has also been studied for peatland improvement for similar purposes (Talib et al. 2021), while Jumien et al. (2023) examined the use of cement and quarry dust as additives, finding them effective as well. Altogether, more research is needed on the subject areas presented in this chapter.
Costs of Peatland Restoration Projects
It is important to assess peatland conditions before and after restoration projects to evaluate both economic and ecological outcomes. Such studies are lacking (although on the rise), especially concerning long-term effects/results, and should be carried out more in the future. The models used in these studies should be developed further. According to an earlier paper on the subject (Moxey and Moran 2014), capital costs of peat land restoration were assumed to fall in an illustrative range of 250 to 12,500 €/ha (indicated in the literature). The large variation in estimates is due to the differences in the prices of restoration methods and the measures that have to be resorted to. This is influenced not only by the methods used, but also by the site (e.g. remoteness) to be restored and the objectives of the project. Some projects have clearly cheaper solutions, for example, only blocking grip drains. Other projects have to resort to more expensive solutions, such as vegetation restoration and, in addition, lost agricultural income.
In a Finnish study (Rehell et al. 2014), restoration measures of a wet, swampy mire were found to cost about 800 €/ha on the treated area, but when impacts over the wider affected area are considered, the cost dropped to roughly 90 €/ha. These calculations excluded planning and supervision costs. According to a study reviewing peatland restoration costs in Lithuania and other countries, restoring 1 ha of peatlands in Lithuania (including works such as dam installation, vegetation removal, and drainage destruction) costs about 800 €/ha, while in some countries, such as Germany, costs may reach 3,000 €/ha (Greifswald Mire Centre 2020).
Glenk et al. (2022) analysed a database of peatland restoration activities from 142 projects and 323 sites in Scotland, of which 300 were suitable for analysis. Data came from two types of forms completed by applicants and grantees: application forms and final reporting forms. Restoration costs varied widely by activity type and initial peatland condition. Based on reported actual costs, the mean restoration cost was 2000 €/ha (median 1200 €); excluding outliers, the mean decreased to 1400 €/ha. On average, project management accounted for about 10% and non-monetary contributions for about 8% of total costs. Forest-to-bog restoration roughly doubled per-hectare costs compared to other activities.
Use of Peat for Soil Improvement and Cultivation
Peat itself can be used for soil improvement. It is important in commercial horticulture, as it supports plant growth, helping plants to trap CO2 from ambient air and return it to the soil. The carbon is then stored to the soil due to its high content of organic matter. The part of peat used for soil improvement and as a growing medium comes from the surface layers of peatlands, not from the deeper layers suitable for combustion. This material can be used for soil amendment, as a sorbent or bedding material or as compost (Järvinen and Hänninen 1992). The use of peat as a growing medium is being replaced. Several organic materials, such as wood bark, wood fibers, coconut fiber, other coconut-based products, and green compost, are suitable alternatives to peat (Gruda et al. 2024).
Ma et al. (2022) demonstrated that a BHA (bentonite-humic acid) addition improved and better-preserved soil ecosystem balance and agricultural crop yield. This was reached by effective soil hydrological regulation, soil enzyme functioning, as well as nutrient exchange in surface and subsoil, leading to efficient water and nutrients usage by oat crops, and a corresponding increase in grain protein, crop yield, efficiency of water use, and overall productivity response per unit of nitrogen applied (nitrogen partial factor productivity). Liu et al. (2022) investigated the effect of peat and bentonite additions on substrate-less remediation in heavy metal-contaminated areas. They found that the additions improved plant growth and reduced the bioavailability of heavy metals. Cao (2019) noted in his study that adding peat significantly altered the physico-chemical properties of sandy soil.
Peat is uniform in quality, porous, and resistant to compaction, making it a durable substrate, especially in dry soils. Compost, though variable in composition and prone to compaction, is more nutrient-rich and biologically active. Peat has low nutrient content but enhances soil CEC and suits acidophilic plants, whereas compost is generally neutral to slightly alkaline. Peat is difficult to re-wet once dry and typically free of weed seeds; well-processed compost can be similar. Compost is commonly used as a top dressing, while peat is less ideal due to surface drying and moisture absorption. Despite its lower cost, peat use raises environmental concerns due to its slow regeneration, carbon emissions, and peatland degradation, potentially delaying the shift to sustainable alternatives (Government of Ireland 2019).
TREATMENT OF PEAT BOG DRAINAGE WATER
Regarding negative aspects of peat production, peat bog drainage water (PBDW) generation is one of the main issues mentioned due to its potentially adverse environmental effects. The humic substances (HS) content in water bodies varies seasonally and annually, mainly influenced by rainfall. In one study (Tuukkanen et al. 2017), water quality data were gathered and analyzed from 15 peat extraction sites in Finland (located in different parts of the country) during years 2011 to 2012 (336 total samples were taken). Table 2 was compiled based on the data presented in the article.
Table 2. Peat Extraction Runoff Water Quality Data Variation
The fluctuation in PBDW pollutant concentrations and load has been associated with the intensity of drainage, soil geochemical properties, and the rate of runoff. Due to the wide variations in PBDW quality, selection of suitable water treatment methods is challenging. Thus, different treatment methods designed to comply with the requirements of the peat production process, local hydrology and geology, the sensitivity of the receiving water bodies and current legal standards are necessary at different sites. This is the situation at least in Finland, where regulatory authorities determine purification requirements for each case separately (Heiderscheidt 2016). PBDW is derived from extraction of peat and is typically mildly acidic and colored. It contains the nutrients phosphorus (P) and nitrogen (N), in addition to HS and total solids (TS) (Kuokkanen et al. 2015). Excessive nutrient inputs into aquatic systems cause oversaturation, triggering algal blooms, which in turn leads to eutrophication (Zhao and Sengupta 1998; Bektaş et al. 2004; Alvarez-Vázquez et al. 2014). This will lead to the oxygen level of water being depleted and water light penetration being hindered, thus being detrimental to the organisms present in the aquatic environment as well as causing biodiversity decrease (Bektaş et al. 2004; Alvarez-Vazquez et al. 2014). HS are residues of biological substances (by microbial activity), of which the organics contained in natural waters are mostly comprised of (Jones and Bryan 1998; Seida and Nakano 2000; Yildiz et al. 2007; Ghernaout et al. 2009).
The main components of HS in water are humic acids (HA), fulvic acids and humins. HA are weakly acidic aliphatic and aromatic compounds, which contain various functional groups (e.g., -COOH and phenolic -OH groups), and their presence in natural water causes the water color to become darker (O’Melia et al. 1999; Motheo and Pinhedo 2000; Prado and Airoldi 2003; Seredynska-Sobecka et al. 2006; Naddeo et al. 2007).
In addition to esthetic problems, this will further prevent light from reaching deeper parts of the water body. Overall, HS are non-homogenous and have very complex chemical structures and a high molecular weight (several hundreds g/mol or larger), and their physicochemical properties are not clearly defined (Hesse et al. 1999; Motheo and Pinhedo 2000). Because of their high stability, HS are also resistant to microbial attack (Motheo and Pinhedo 2000). HS are the end-product of nature’s biodegradative and oxidative processes, making them essentially non-biodegradable; however, their high aromatic and aliphatic residue content allows them to be readily aggregated and precipitated by charge neutralization (Jones and Bryan 1998; Ødegaard et al. 1999; Yildiz et al. 2007; Yildiz et al. 2008). Water containing HS may also be treated using other potential methods, such as physicochemical, biological, and membrane processes, etc. Usage of peatland buffer areas and/or wetlands are examples of classical methods that are of particular interest in HS removal. Traditional PBDW treatment methods have often limited effectiveness. Therefore, new methods are needed. For example, electrocoagulation (EC) has also been suggested to be an effective new method to treat PBDW (Kuokkanen et al. 2015; Postila 2016). While theoretically possible, capturing methane from peat water would require precise control and closed systems, which is currently impractical. In addition to treatment technologies, spatial planning tools have also been developed to support water protection in peatland forestry. Niemi et al. (2022) introduced a GIS-based method for identifying suitable locations for water protection structures, such as overland flow fields and uncleaned ditch sections. Using high-resolution lidar data, the method enabled detailed terrain analysis and was tested in the Kovesjärvi catchment area (Parkano, Western Finland). Field evaluations confirmed most suggested sites as suitable, highlighting the method’s applicability in forest management planning.
Basic and Enhanced Methods
Numerous water purification methods have been developed or modified for use in the conditions found at peat extraction sites, aiming to reduce the load of pollutants caused by this type of land use (Kløve 2001; Heiderscheidt 2016).