Saran Sohi

The University of Edinburgh | UoE · School of GeoSciences

Studying the changes and linkages between dissolved organic matter (DOM) and microorganisms in soils during vegetation restoration will help to understand the role of vegetation restoration in soil carbon sequestration and thus improve the understanding of the global soil carbon cycle. Soil DOM molecules were characterized by Fourier-transform ion...

Purpose Phosphorus (P) is a limiting nutrient in many managed forests. To further understand the risks and benefits of biochars as sustainable P source in forest management, an improved mechanistic understanding of its interactions in root systems is required. Methods A rhizobox experiment was conducted to observe root response of P. sylvestris (S...

Purpose Phosphorus (P) is a limiting nutrient in many managed forests. To further understand the risks and benefits of biochar as a sustainable P source in forest management, an improved mechanistic understanding of its interactions in root systems is required. Methods A rhizobox experiment was conducted to observe root response of P. sylvestris (S...

The long-term stability of biochar in soil is key for carbon capture and storage and soil amelioration. Yet, its assessment is hampered by the long time-horizons needed to actually probe biochar’s stability. Therefore, quick and reliable estimation methods are sought. Analytical pyrolysis (Py-GC-MS) offers a quick tool to predict biochar’s stabilit...

Greenhouse gas removal technologies are needed to reach the targets of the UNFCCC Paris Agreement. Among existing technologies, the use of biochar is considered promising, particularly biochar derived from the large quantities of sugarcane residues available in South America and elsewhere. However, the net greenhouse gas removal potential of sugarc...

Peat remains the primary constituent of horticultural growing media in professional use. However, use of peat in horticultural growing media results in greenhouse gas emissions and biodiversity loss due to excavation of natural peatlands. Biochar is gaining attention as a sustainable alternative to peat use in horticulture. This study examined the...

The charosphere, the interface microzone between biochar and soil, plays a vital role in biochemical processes following biochar application to soil. However, the development of the charosphere over time, and the pH dynamics within and around it, remain poorly understood as biochar ages. In this study, two kinds of biochars with distinct characteri...

Sugarcane (Saccharum officinarum L.) cultivation leaves behind around 20 t ha−1 of biomass residue after harvest and processing. We investigated the potential for sequestering carbon (C) in soil with these residues by partially converting them into biochar (recalcitrant carbon-rich material). First, we modified the RothC model to allow changes in s...

Besides the feedstock composition, the highest treatment temperature (HTT) in pyrolysis is one of the key production parameters. The latter determines the feedstock’s carbonization extent, which influences physicochemical properties of the resulting biochar, and in consequence its performance in industrial and agricultural applications. The actual...

With the advent of mechanized sugarcane harvesting in Brazil around 70 Mt of straw each year is left on the field, and ∼70% of its carbon (C) is decomposed and returned to the atmosphere on the same timeframe. The adoption of a stabilised C product such as biochar as a vehicle for nutrient delivery might address two ends of a problem: to increase n...

Management of urban brownfield land can contribute to significant removal of atmospheric CO2 through the development of soil carbonate minerals. However, the potential magnitude and stability of this carbon sink is poorly quantified as previous studies address a limited range of conditions and short durations. Furthermore, the suitability of carbon...

To limit warming to well below 2°C, most scenario projections rely on greenhouse gas removal technologies (GGRTs); one such GGRT uses soil carbon sequestration (SCS) in agricultural land. In addition to their role in mitigating climate change, SCS practices play a role in delivering agroecosystem resilience, climate change adaptability, and food se...

Biochar is being examined as a potential sorbent for organic pollutants in the environment including phthalate esters (PAEs). It has been noted that nano-scale biochar particles displayed stronger migration potential than other particles, which poses the potential risk of pollutant transfer through the environment. In this present study, we examine...

Biochar still lacks widespread and large-scale applications. Past concepts have failed to define systems that are economically attractive, new ways to deliver biochar's environmental benefits are needed. This chapter starts by evaluating the original idea of biochar as a simple soil amendment and the implications of depending on a price for carbon...

To address inorganic and organic contaminants in the environment, economic new adsorbents are required. Here we test magnetic biochar for efficient capture of the typical pollutants Cr(VI) and trichloroethylene (TCE) from solution. We used a simple synthesis using 2M FeCl3 solution and peanut hull biomass to prepare magnetic ZVI biochar at alternat...

The removal of phosphorus (P) from sewage effluents is necessary to control eutrophication in receiving waters. Biochar has been proposed and is investigated for the capture and reuse of P, however the forces driving and limiting P adsorption are still largely unclear. To identify the forces governing P uptake by biochar, biochars with markedly dif...

Rapid formation of stable soil carbonates offers a potential biologically-mediated strategy for removing atmospheric CO2 and forms a part of the negative emissions debate in a bid to maintain global temperatures of 1.5 °C. Microbial respiration in soil and respiration by plant roots leads to high partial pressure of CO2 below ground. Given adequate...

Our results show clear changes in the dominant mechanism of atrazine sorption by biochar and hydrochar and their surface functionality resulting from ageing.

Aside from its use for improving soil properties, biochar is increasingly promoted as a direct nutrient provider for sustainable recycling of waste materials. However, incomplete understanding of the interacting factors that determine P release from biochar may limit the efficiency of P recycling from biochar to soil. In particular, the contrasting...

The editorial “Sifting Through the Embers”1 is topical and nicely identifies some key needs in biochar research. The common issue of insufficient information on biochar production and characteristics to allow for replication of research or to benchmark findings of other researchers is also clearly highlighted. The development of standardised refere...

Food insecurity and declining soil fertility across much of sub-Saharan Africa in recent decades have led to pursuit of alternative nutrient management strategies for both improving crop yields and the restoration of degraded soils. In this respect, a 3-year field based studies involving two sites (Ayuom and Kwadaso) of contrasting soils (Suko and...

The effects of different biochars on in vitro rumen gas production and fermentation characteristics were investigated using a two (biochar inclusion level, 10 and 100 g biochar/kg substrate) x two (process temperature, 550 or 700 °C) × five (biomass source, Miscanthus straw, oil seed rape straw, rice husk, soft wood pellets or wheat straw) factoria...

Users of biochar in the field require this product to reliably meet its declared specifications. For the first time, this work investigated, whether these specifications could be reproducibly obtained as a sole function of the thermal history of the biomass feedstock during slow pyrolysis, irrespective of the type and scale of the production unit....

Human activities have massively altered the global nitrogen (N) cycle, doubling annual production of reactive N (Nr) compounds from atmospheric dinitrogen (N2). The use of 120 Mt year⁻¹ fertilizer N, with a global terrestrial/atmospheric N fixation of 285Mtyear⁻¹, has provided huge benefits for global food production. However, nitrogen use efficien...

Addressing food security issues arising from phosphorus (P) scarcity is described as one of the greatest global challenges of the 21st Century. Dependence on inorganic phosphate fertilisers derived from limited geological sources of P creates an urgent need to recover P from wastes and treated waters, in safe forms that are also effective agricultu...

Roadside verges in Britain support 238,000 hectares of vegetated land and approximately 10 hectares of vegetated central reserves. These areas have the potential to be engineered in such a way that they deliver a range of ecosystem services including flood regulation and biodiversity conservation in addition to their primary functions such as comfo...

Peat is used as a high quality substrate for growing media in horticulture. However, unsustainable peat extraction damages peatland ecosystems, which disappeared to a large extent in Central and South Europe. Furthermore, disturbed peatlands are becoming a source of greenhouse gases due to drainage and excavation. This study is the result of a work...

AbstractAlthough increasing numbers of research papers regarding biochar are being published worldwide, in some countries growing interest in biochar has only recently been observed; this is true of Poland. We analysed information on biochar research in Poland alongside lessons learned elsewhere in order to identify the significant opportunities an...

A multi-technique analysis was performed on a range of biochar materials derived from secondary organic resources and aimed at sustainable recovery and re-use of wastewater phosphorus (P). Our purpose was to identify mechanisms of P capture in biochar and thereby inform its future optimisation as a sustainable P fertiliser. The biochar feedstock co...

Biochars produced from marginal biomass feedstocks are a potential source of recycled nutrients for agriculture, but may also contain potentially toxic elements (PTEs) which can cause phytotoxicity. We assessed the potential for nutrient recycling from such materials against potential environmental risks in 17 biochars containing high concentration...

Recent research has demonstrated considerable potential for artificial soils to be designed for carbon capture. The incorporation of quarry fines enables the accumulation of atmospheric CO 2 in newly formed carbonate minerals. However, the rate and trajectory of carbon accumulation has been little studied. The relative contribution of biotic (e.g....

Climate change poses a fundamental threat to humanity, and thus solutions for both mitigation and adaptation strategies are becoming increasingly necessary. Biochar can offer a range of environmental services, such as reclamation of degraded land, improvement of soil fertility and carbon sequestration. However, it also raises questions, regarding s...

Roadside verges in Britain support 238,000 hectares of vegetated land and approximately 10 hectares of vegetated central reserves. These areas have the potential to be engineered in such a way that they deliver a range of ecosystem services such as flood regulation and biodiversity conservation in addition to their primary functions such as comfort...

Following the introduction, Chapter 2 provides an overview of mitigation in the forest sector, addressing the handling of forests under UNFCCC. Chapters 3 to 5 focus on forest-based mitigation options – afforestation, reforestation, REDD+ and forest management – and Chapters 6 and 7 focus on wood-product based options – wood energy and green buildi...

There is a lack of models to predict soil inorganic carbon (SIC) which are not only multipurpose, but can predict SIC in a variety of soils and materials. The importance of estimating SIC stocks is due to the large contribution they make towards total carbon in some soils. This paper proposes such a model which aims to account for the variance and...

Recovery and re-use of phosphorus (P) from wastewater treatment systems as agricultural fertiliser presents an important and viable target for P waste reduction and recycling. In this study novel biochar materials for P filtration of wastewater were designed and produced using waste feedstocks, with consideration of the plant accessibility of the P...

Biochar is a product with multiple functions and a range of uses, and which could be manufactured from a range of biomass types, including wood and forest residues. Economic production and use of biochar may take place within spatial boundaries that contrast greatly in total area and patchiness. At the moment, however, biochar is generally consider...

Grassland soils play a key role in climate change and food security, and carbon (C) and nitrogen (N) mineralization is central to this. Although there are a number of mathematical models available to estimate C and N mineralization, they do not encompass the variability of the process and there is uncertainty in their predictions. The input paramet...

Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, the COST Action TD1107 conducted an inter-laboratory comparison, in whi...

Land-use change (LUC) is a major influence on soil organic carbon (SOC) stocks and the global carbon cycle. LUC from conventional agricultural to biomass crops has increased in Britain but there is limited understanding of the effects on SOC stocks. Results from paired plot studies investigating site-specific effects document both increasing and de...

Urban soils that contain materials derived from demolition undergo carbonation as a consequence of a reaction between Ca derived from cement and concrete, and carbonate ultimately derived from the atmosphere. Estimated rates of CaCO 3 accumulation are equivalent to the removal of 150T CO 2 ha-1 yr-1. Although this process has benefits for carbon ca...

The increase in global temperature and the continuing threat of climate change has occurred due to rapid escalation of atmospheric greenhouse gas concentrations, especially CO2. This is directly related to human activity and comparatively recent combustion of fossil fuels. To compensate for the anthropogenic emissions of CO2, it is essential to opt...

The increase in global temperature and the continuing threat of climate change has occurred due to rapid escalation of atmospheric greenhouse gas concentrations, especially CO2. This is directly related to human activity and comparatively recent combustion of fossil fuels. To compensate for the anthropogenic emissions of CO2, it is essential to opt...

The increase in global temperature and the continuing threat of climate change has occurred due to rapid escalation of atmospheric greenhouse gas concentrations, especially CO2. This is directly related to human activity and comparatively recent combustion of fossil fuels. To compensate for the anthropogenic emissions of CO2, it is essential to opt...

Brownfield ecosystem multifunctionality: Engineering carbon capture and other ecosystem services in the urban environment

Recent research into soil engineering indicates that increased carbon sequestration through the conversion of atmospheric CO 2 to a pedogenic carbonate mineral (calcite, CaCO 3) may help mitigate global warming through artificially engineering a variety of soils with selected materials and vegetation so that they have a photosynthesis-driven carbon...

Since land-use change (LUC) to lignocellulosic biomass crops often causes a loss of soil organic carbon (SOC), at least in the short term, this study investigated the potential for pyrogenic carbon (PyC) to ameliorate this effect. Although negative priming has been observed in many studies, most of these are long term incubation experiments which d...

Second-generation bioenergy crops, including Short Rotation Forestry (SRF), have the potential to contribute to greenhouse gas (GHG) emissions savings through reduced soil GHG fluxes and greater soil C sequestration. If we are to predict the magnitude of any such GHG benefits a better understanding is needed of the effect of land use change (LUC) o...

The characterisation of biochar has been predominantly focused around determining physicochemical properties including chemical composition, porosity, and volatile content. To date, little systematic research has been done into assessing the properties of biochar that directly relate to its function in soil and how production conditions could impac...

There is increasing interest in the use of nonfood second-generation lignocellulosic feedstocks and a move away from food crops for bioenergy applications, but questions still remain on sustainability. Empirical data are needed to quantify the GHG balance of land-use transition to lignocellulosic bioenergy cropping systems, to inform lifecycle anal...

Biochar application to soil is currently widely advocated for a variety of reasons related to sustainability. Typically, soil amelioration with biochar is presented as a multiple-‘win’ strategy, although it is also associated with potential risks such as environmental contamination. The most often claimed benefits of biochar (i.e. the ‘wins’) inclu...

Although biochar is often regarded as inert, it can be oxidized, and finally mineralized into carbon dioxide. However, it is unclear how much of this material is rapidly oxidized, that is, how much remain in the soil for longer periods. Efforts have been undertaken to develop methodologies to quantify the stable fraction present in biochar, quickly...

Twenty seven methods currently used to characterize biochar were assessed in terms of their usefulness to determine the stability of biochar carbon in the environment. The International Biochar Initiative (IBI), which led the effort, gathered fourteen world-class experts in different fields of biochar relevant to stability, who guided the process f...

Roots are the first point of contact between biochar particles and growing plants, yet detailed studies of biochar–root interactions are few. Biochar may affect root growth, and therefore plant performance, through two mechanisms: (i) as a direct nutrient source and (ii) through impacts on nutrient availability. To test the hypothesis that biochar–...

Soil physical fractionation techniques may provide indicators of changing soil organic carbon (SOC) content; however, they have not been widely tested on volcanic soils (Andisols). In this study, we assessed two fractions as potential indicators in volcanic soils, using two sites in Chile converted from natural grassland to arable and mixed crop ro...

The effect of rice-husk char (potentially biochar) application on the growth of transplanted lettuce (Lactuca sativa) and Chinese cabbage (Brassica chinensis) was assessed in a pot experiment over a three crop (lettuce-cabbage-lettuce) cycle in Cambodia. The biochar was the by-product of a rice-husk gasification unit and consisted of 28.7% carbon (...

Manure generated by intensive livestock operations poses potential ecological risk in the form of water pollution and greenhouse gas emission. To assess the impact of biochar on coarse-textured soils under contrasting nutrient management regimes, a 55-d incubation was conducted using unplanted soil columns amended with manure, slurry, or fertilizer...

The greatest contributors to global greenhouse gases (GHG's) are CO2 emissions from fossil fuel use and following land use change (LUC). Globally, soils contain three times more carbon than the atmosphere and have the potential to act as GHG sources or sinks. A significant amount of land may be converted to bioenergy production to help meet UK 2050...

Climate change impacts resulting from fossil fuel combustion and concerns about the diversity of energy supply are driving interest to find low-carbon energy alternatives. As a result bioenergy is receiving widespread scientific, political and media attention for its potential role in both supplying energy and mitigating greenhouse (GHG) emissions....

We recently established a procedure that imposes oxidatiave ageing to biochar and charcoal samples over a short time-frame, that provided carbon mass loss in the range projected for wild-fire charcoal in soil over a period of approximately 100 years. The stability of biochar samples in soil (relative to charcoal) range from 45-98% could be determin...

Biochar is the solid, carbon rich product of heating biomass with the exclusion of air (pyrolysis). Whereas charcoal is derived from wood, biochar is a co-product of energy capture and can derive from waste or non-waste, virgin or non-virgin biomass resources. But also, biochar is not a fuel - rather it is intended for the beneficial amendment of s...

To assess the value of biochar to direct supply of crop nutrients we considered the release of phosphorus, magnesium and potassium from a hardwood biochar in a sequential leaching experiment with deionized water. Cumulative P release was proportionally large despite being quantitatively small, and the sixth extraction yielded 44–73% of the first, i...