Erik Karltun

• PhD
• Swedish University of Agricultural Sciences

The long-term persistence of biochar in soil is often predicted by extrapolating mineralization data from short-term laboratory incubations. Single first-order, double first-order, triple first-order and power models have been employed for this purpose, all of which have an inherent assumption that biochar is biodegradable. However, recent insights...

Tree biomass is a key variable for estimating the carbon stock potential of the forest. This study aimed to quantify the belowground biomass (BGB), aboveground biomass (AGB), and carbon stock of Acacia decurrens across stand ages. The study was conducted at four different stand ages (three, four, five, and six year old stands), and it was replicate...

Correct estimation of tree biomass is important when calculating uptake or emission of CO2 in relation to land-use and land-use change. The objectives of this study were (1) to estimate the root/shoot ratio for the estimation of root biomass based on the above-ground biomass (AGB) of Acacia mearnsii, and (2) to develop allometric equations for the...

The climate change mitigation benefits of biochar systems arise largely from carbon storage in biochar. However, while biochar is increasingly recognized as a carbon dioxide removal technology, there are on-going scientific discussions on how to estimate the persistence of biochar carbon when biochar is used in soils. Estimates vary from decades to...

The biochar-agriculture nexus can potentially generate several benefits ranging from soil carbon sequestration to the reduction in nutrient leaching from arable soils. However, leveraging these benefits requires spatially-explicit information on suitable locations for biochar application. This study provides a flexible multicriteria framework that...

Biochar is a material derived from biomass pyrolysis that is used in urban applications. The environmental impacts of new biochar products have however not been assessed. Here, the life cycle assessments of 5 biochar products (tree planting, green roofs, landscaping soil, charcrete, and biofilm carrier) were performed for 7 biochar supply-chains in...

Despite efforts to increase agricultural production sustainably in sub-Saharan Africa, large gaps remain between actual and potential yield of food crops. Adding biochar to degraded cropland soils in the African tropics has significant potential to enhance crop productivity. Biochar-based farming can also mitigate climate change, through soil carbo...

The biochar-agriculture nexus can potentially generate several benefits ranging from soil carbon sequestration to reduction in nutrient leaching from arable soils. However, leveraging these benefits for a particular objective requires spatially-explicit information on suitable locations for biochar application. This study provides a flexible multi-...

A short-term field trial was carried out with the purpose to examine the impact of 2 different biochar fertilizer blends (BFB) on soil fertility and crop yield for a crop with a high revenue per hectare. The biochar field trial with 5 different treatments was conducted in a 2-year-old asparagus plantation on postglacial sand soil on Gotland. Beside...

There is a growing societal demand to increase the use of forest biomass for substitution of fossil fuels. The production of this biomass must be sustainable and an indicator for critical biomass harvesting (CBH) has been suggested in order to sustain forest soil fertility and mitigate soil acidification at whole-tree harvesting. The CBH indicator...

The status of the soil organic carbon (SOC) stock at any position in the landscape is subject to a complex interplay of soil state factors operating at different scales and regulating multiple processes resulting either in soils acting as a net sink or net source of carbon. Forest landscapes are characterized by high spatial variability, and key dr...

Boreal forest soils are important global carbon sinks, with significant storage in the organic topsoil. Decomposition of these stocks requires oxidative enzymes, uniquely produced by fungi. Across Swedish boreal forests, we found that local carbon storage in the organic topsoil was 33% lower in the presence of a group of closely related species of...

Biochar has been recognised as a carbon dioxide removal (CDR) technology. Unlike other CDR technologies, biochar is expected to deliver various valuable effects in e.g. agriculture, animal husbandry, industrial processes, remediation activities and waste management. The diversity of biochar side effects to CDR makes the systematic environmental ass...

The input of acidity to Swedish forest soils through forestry between 1955 and 2010 is compared with the acid input from atmospheric deposition. Depending on region, input of acidity from forestry was the minor part (25–45%) of the study period’s accumulated acid input but is now the dominating source (140–270 mol c ha ⁻¹ year ⁻¹ ). The net uptake...

Eucalyptus saligna is one of the exotic tree species in Ethiopia. Small scale farmers in Ethiopia plants Eucalyptus saligna widely compared to other tree species. The major objective of the study was to assess the reasons for the expansion of on-farm plantation of Eucalyptus saligna and its associated nutrient export in Gambo watershed, Arsi Zone O...

The status of the SOC stock at any position in the landscape is subject to a complex interplay of soil-state factors operating at different scales and regulating multiple processes resulting either in soils acting as a net sink or net source of carbon. Forest landscapes are characterized by high spatial variability and key drivers of SOC stock migh...

Several small-scale pyrolysis plants have been installed on Swedish farms and uptake is increasing in the Nordic countries. Pyrolysis plants convert biomass to biochar for agricultural applications and syngas for heating applications. These projects are driven by ambitions of achieving carbon dioxide removal, reducing environmental impacts, and imp...

Biochar produced in cookstoves has the potential to contribute to negative carbon emissions through sequestration of biomass carbon while also providing other benefits for sustainable development, including provision of clean renewable energy and increased yields in tropical agriculture. The aim of the reported research was to estimate effects on f...

Majority of households in sub-Saharan Africa (SSA) cook with charcoal and/or firewood using inefficient stoves. This leads to high consumption of wood fuel as well as exposure to the negative effects of indoor air pollution, which disproportionately affects women and children. Concurrently, the rural population in SSA depends on agriculture, which...

Several cities in Sweden are aiming for climate neutrality within a few decades and for negative emissions thereafter. Combined biochar, heat and power production is an option to achieve carbon sequestration for cities relying on biomass-fuelled district heating, while biochar use could mitigate environmental pollution and greenhouse gas emissions...

Application of biochar has been shown to increase soil fertility and enable soil carbon sequestration, indicating potential for agricultural and environmental benefits from using locally produced biochar on African smallholder farms. However, previous studies have been rather short-term and little is known about the longer-term effects of biochar a...

This study investigated the variation of soil organic carbon in four land cover types: natural and mixed forest, cultivated land, Eucalyptus plantation and open bush land. The study was conducted in the Birr watershed of the upper Blue Nile (‘Abbay’) river basin. The data was subjected to a two-way of ANOVA analysis using the general linear model (...

Boreal forest soils retain significant amounts of carbon (C) and nitrogen (N) in purely organic layers, but the regulation of organic matter turnover and the relative importance of leaf litter and root‐derived inputs are not well understood. We combined bomb ¹⁴C dating of organic matter with stable isotope profiling for Bayesian parameterization of...

Total ecosystem carbon (C) stocks in tree biomass (aboveground and belowground), litter layer and soil (0–50 cm depth) were quantified in mountain miombo woodland and in 34-year-old first-rotation plantations of Pinus taeda and Eucalyptus grandis. The study was performed at three sites (Penhalonga, Rotanda and Inhamacari) in the western highlands o...

Plant–soil interactions link ecosystem fertility and organic matter accumulation below ground. Soil microorganisms play a central role as mediators of these interactions, but mechanistic understanding is still largely lacking. Correlative data from a coniferous forest ecosystem support the hypothesis that interactions between fungal guilds play a c...