ECOSSE: Estimating Carbon in Organic Soils - Sequestration and Emissions: Final Report

Background Climate change, caused by greenhouse gas ( GHG) emissions, is one of the most serious threats facing our planet, and is of concern at both UK and devolved administration levels. Accurate predictions for the effects of changes in climate and land use on GHG emissions are vital for informing land use policy. Models which are currently used to predict differences in soil carbon (C) and nitrogen (N) caused by these changes, have been derived from those based on mineral soils or deep peat. None of these models is entirely satisfactory for describing what happens to organic soils following land-use change. Reports of Scottish GHG emissions have revealed that approximately 15% of Scotland's total emissions come from land use changes on Scotland's high carbon soils; the figure is much lower for Wales. It is therefore important to reduce the major uncertainty in assessing the carbon store and flux from land use change on organic soils, especially those which are too shallow to be deep peats but still contain a large reserve of C. In order to predict the response of organic soils to external change we need to develop a model that reflects more accurately the conditions of these soils. The development of a model for organic soils will help to provide more accurate values of net change to soil C and N in response to changes in land use and climate and may be used to inform reporting to UKGHG inventories. Whilst a few models have been developed to describe deep peat formation and turnover, none have so far been developed suitable for examining the impacts of land-use and climate change on the types of organic soils often subject to land-use change in Scotland and Wales. Organic soils subject to land-use change are often (but not exclusively) characterised by a shallower organic horizon than deep peats (e.g. organo-mineral soils such as peaty podzols and peaty gleys). The main aim of the model developed in this project was to simulate the impacts of land-use and climate change in these types of soils. The model is, a) be driven by commonly available meteorological data and soil descriptions, b) able to simulate and predict C and N turnover in organic soils, c) able to predict the impacts of land-use change and climate change on C and N stores in organic soils in Scotland and Wales. In addition to developing the model, we have undertaken a number of other modelling exercises, literature searches, desk studies, data base exercises, and experimentation to answer a range of other questions associated with the responses of organic soils in Scotland and Wales to climate and land-use change. Aims of the ECOSSE project The aims of the study were: To develop a new model of C and N dynamics that reflects conditions in organic soils in Scotland and Wales and predicts their likely responses to external factors To identify the extent of soils that can be considered organic in Scotland and Wales and provide an estimate of the carbon contained within them To predict the contribution of CO 2, nitrous oxide and methane emissions from organic soils in Scotland and Wales, and provide advice on how changes in land use and climate will affect the C and N balance In order to fulfil these aims, the project was broken down into modules based on these objectives and the report uses that structure. The first aim is covered by module 2, the second aim by module 1, and the third aim by modules 3 to 8. Many of the modules are inter-linked. Objectives of the ECOSSE project The main objectives of the project were to: Describe the distribution of organic soils in Scotland and Wales and provide an estimate of the C contained in them Develop a model to simulate C and N cycling in organic soils and provide predictions as to how they will respond to land-use, management and climate change using elements of existing peat, mineral and forest soil models Provide predictive statements on the effects of land-use and climate change on organic soils and the relationships to GHG emissions, including CO 2, nitrous oxide and methane. Provide predictions on the effects of land use change and climate change on the release of Dissolved Organic Matter from organic soils Provide estimates of C loss from scenarios of accelerated erosion of organic soils Suggest best options for mitigating C and N loss from organic soils Provide guidelines on the likely effects of changing land-use from grazing or semi-natural vegetation to forestry on C and N in organic soils Use the land-use change data derived from the Countryside Surveys of Scotland and Wales to provide predictive estimates for changes to C and N balance in organic soils over time

Mycorrhizas and biomass crops: opportunities for future sustainable development

Central to soil health and plant productivity in natural ecosystems are in situ soil microbial communities, of which mycorrhizal fungi are an integral component, regulating nutrient transfer between plants and the surrounding soil via extensive mycelial networks. Such networks are supported by plant-derived carbon and are likely to be enhanced under coppiced biomass plantations, a forestry practice that has been highlighted recently as a viable means of providing an alternative source of energy to fossil fuels, with potentially favourable consequences for carbon mitigation. Here, we explore ways in which biomass forestry, in conjunction with mycorrhizal fungi, can offer a more holistic approach to addressing several topical environmental issues, including ‘carbon-neutral’ energy, ecologically sustainable land management and CO2 sequestration

Mycorrhizal fungal abundance is affected by long-term climatic manipulations in the field

Climate change treatments - winter warming, summer drought and increased summer precipitation - have been imposed on an upland grassland continuously for 7 years. The vegetation was surveyed yearly. In the seventh year, soil samples were collected on four occasions through the growing season in order to assess mycorrhizal fungal abundance. Mycorrhizal fungal colonisation of roots and extraradical mycorrhizal hyphal (EMH) density in the soil were both affected by the climatic manipulations, especially by summer drought. Both winter warming and summer drought increased the proportion of root length colonised (RLC) and decreased the density of external mycorrhizal hyphal. Much of the response of mycorrhizal fungi to climate change could be attributed to climate-induced changes in the vegetation, especially plant species relative abundance. However, it is possible that some of the mycorrhizal response to the climatic manipulations was direct - for example, the response of the EMH density to the drought treatment. Future work should address the likely change in mycorrhizal functioning under warmer and drier conditions

BIOAUGMENTATION OF PCP IN TWO DIFFERENT SOILS BY Sphingomonas chlorophenolica ATCC 39723

The objective of this paper was study the Pentachlorophenol (PCP) degradation by Sphingomonas chlorophenolica in two different types of soils: a loamy and a sandy soil in the presence and absence of plants (Winter wheat). Measurements of PCP concentrations were carried out in a laboratory basis using High performance liquid chromatography (HPLC). The toxic effect of PCP on plants was studied through the monitoring of plant weight and root length. The biodegradation of PCP by S. chlorophenolica in two different kinds of soil was assessed with a bioluminescence assay of Escherichia coli HB101 pUCD607. Bacterial analyses were carried out by plating on three culture media: MSM (Mineral Salt Medium) for Sphingomonas chlorophenolica, MSM for PCP_degrading/tolerant organisms and Trypticase Soy Broth Agar (TSBA,) for heterotrophic organisms. The introduction of S. chlorophenolica into the loamy soil with plants showed a faster degradation when compared to the inoculated soil without plants. The monitoring of the plant growth showed a protective role of S. chlorophenolica against the toxicity of PCP in the loamy soil. The bioassay confirmed that initial toxicity was lower while degradation progressed. In the sandy soil, there was no significant degradation of PCP and HPLC determination suggested that more than 75 % of PCP was sorbed into the soil. The presence of the inoculum did not significantly enhance the degradation of PCP. There was no  deleterious effect of PCP to the growth of winter wheat in this type of soil when plant weight and root length were measured. In both soils there was a significant increase of S. chlorophenolica, heterotrophic and PCPdegrading/ tolerant organisms in the roots when compared to those in the soil. This study showed that the presence of the inoculum S. chlorophenolica enhanced the PCP degradation in a loamy soil and also it has a protective role to prevent phytotoxic effects of PCP on plant growth. The combined use of bioaugmentation and plants suggest that the rhizosphere of certain plant species may be important for facilitating microbial degradation of pesticides in soil with important implications for using vegetation to stabilize and remediate surface soils.O objetivo deste trabalho foi estudar a degradação de pentaclorophenol (PCP) por S. chlorophenolica em dois diferentes tipos de solo (arenoso e argiloso) na presença e ausência de plantas (trigo - Triticum aestivum). As concentrações de PCP foram determinadas mediante Cromatografia a Líquido de Alta Eficiência (CLAE). Os efeitos tóxicos de PCP foram estudados pelo monitoramento do crescimento das plantas (em peso, g) e medidas das raízes (cm). A biodegradação de PCP por S. chlorophenolica  nos dois tipos de solo foi acompanhada por análises de bioluminescência de Escherichia coli HB101 pUCD607. Contagens bacterianas foram realizadas em três meios de cultura: meio mineral para S. chlorophenolica, meio mineral para organismos degradadores/tolerantes ao PCP e ágar triptose caldo de soja para organismos heterotróficos. No solo argiloso com vegetação, a degradação de PCP ocorreu de forma mais rápida após a introdução de S. chlorophenolica que no solo sem plantas. O monitoramento do crescimento da planta mostrou o papel protetivo exercido pela S.chlorophenolica contra a toxicidade do PCP. O bioensaio confirmou que a toxicidade inicial causada pelo PCP diminuiu conforme o prosseguimento da degradação. No solo arenoso não houve degradação significativa. As determinações cromatográficas sugerem que mais de 75% do PCP estava adsorvido ao solo (não-disponível aos organismos degradadores). Não houve efeito deletério de PCP sobre o crescimento da planta nem sobre as raízes. Em ambos os solos houve aumento significativo nas populações bacterianas de Sphingomonas chlorophenolica, organismos PCP-degradadores/tolerantes e heterotróficos quando comparadas com as populações presentes nas raízes. Este estudo mostrou que a presença do inóculo Sphingomonas chlorophenolica melhorou a degradação de PCP em solo argiloso e seu papel protetor contra o efeito fitotóxico do PCP sobre plantas. A rizosfera de certas plantas pode ser importante para facilitar a degradação microbiana de pesticidas em solos com importantes implicações ao se utilizar a vegetação para estabilizar e remediar solos superficiais

Potential use of DNA adducts to detect mutagenic compounds in soil

In this study, three different soils with contrasting features, spiked with 300 mg benzo[a]pyrene (BaP)/kg dry soil, were incubated at 20 °C and 60% water holding capacity for 540 days. At different time points, BaP and {DNA} were extracted and quantified, and {DNA} adducts were quantified by 32P-postlabelling. After 540 days incubation, 69.3, 81.6 and 83.2% of initial BaP added remained in Cruden Bay, Boyndie and Insch soils, respectively. Meanwhile, a significantly different amount of DNA–BaP adducts were found in the three soils exposed to BaP over time. The work demonstrates the concept that {DNA} adducts can be detected on {DNA} extracted from soil. Results suggest the technique is not able to directly reflect bioavailability of BaP transformation products. However, this new method provides a potential way to detect mutagenic compounds in contaminated soil and to assess the outcomes of soil remediation