Displays

80% of peatlands in Indonesia and Malaysia (15% of Earth's soil carbon) are now drained for production of pulp wood and palm oil. Associated increased peat decomposition and large-scale forest fires are now significant contributors to global greenhouse gas emissions. However, carbon losses from these processes and the impact of peatland drainage remain poorly quantified across SE Asia because of the challenging scale and inaccessibility of dense tropical peatland forests.

Space-based platforms offer the opportunity for regular and efficient pan-regional monitoring and overcome inaccessibility of tropical peatland environments. A development in satellite interferometric synthetic aperture radar (InSAR) in monitoring surface motion has the potential to solve this problem. A new ‘intermittent small baseline subset’ (ISBAS) modelling technique provides excellent coverage across almost all land surfaces irrespective of ground cover, enabling long-term measurement of peatland surface motion across whole catchments, regions and countries. Importantly, the ISBAS technique is able to determine surface deformation under tropical forest canopy using C-band InSAR, enabling continuous monitoring of surface motion ranging from 0.1–40cm/yr at spatial scales ≥90x90m.

This project aims to determine whether rate of subsidence of the peat surface measured by ISBAS-InSAR is a proxy for rate of carbon loss in tropical peatlands in SE Asia. ISBAS-InSAR time series and field measurements of subsidence will be used to monitor and characterise seasonal tropical peat surface oscillations over time and field radar experiments will investigate C-band radar signal attenuation with the peat surface at different moisture contents.

How to cite: Ledger, M., Sjögersten, S., Sowter, A., Large, D., Evans, C., and Morrison, K.: Determining regional scale carbon losses from tropical peatlands using ISBAS-InSAR, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4715, https://doi.org/10.5194/egusphere-egu2020-4715, 2020.

Global peatlands store >600 Gt of Carbon (C) but are highly vulnerable to degradation following drainage for agriculture. The extensively drained East Anglian Fens include half of England’s most productive agricultural land, produce ~33% of England’s vegetables and support a food production industry worth approximately £3 billion GBP.  However under arable management, these fen peat soils produce ~37.5 t CO₂ eq ha^-1 of total greenhouse gas (GHG) emissions annually. This is likely to be the largest source of land use GHG emissions in the UK per unit area and there is interest in developing responsible management approaches to reduce emissions whilst maintaining economically productive systems. Lettuce (Lactuca sativa) is amongst the UK’s most valuable crops and a substantial proportion of UK production occurs in the Fens. We undertook a life cycle assessment to compare the carbon footprint of UK Fen lettuce with alternative sources of lettuce for the UK market. We also examined the potential for responsible peat management strategies and more efficient production to reduce the carbon footprint of Fen lettuce. It is hoped this study will help to inform land use decision making and encourage responsible management of UK lowland peat resources.

How to cite: Freeman, B., Styles, D., Evans, C., Chadwick, D., and Jones, D.: Life cycle assessment of horticultural production on UK lowland peat soils., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9662, https://doi.org/10.5194/egusphere-egu2020-9662, 2020.

Peatlands cover three percent of the global land surface. However, they store significant amounts of carbon (C), approximately 30%. Peatlands are drained to support agricultural production. It’s estimated that agriculture exploits approximately 20% of peatlands worldwide. The exploited peatlands are significant emitters of carbon dioxide (CO₂) and nitrous oxide (N₂O). In Europe, agriculture is the second largest contributor of greenhouse gas (GHG) emissions. In addition to GHG emissions, we are fast losing productive peatlands; it’s estimated by 2050, a third of productive peatlands will be lost. Loss of productive peatlands will affect productivity and food security.

To prolong use of peatlands, ploughing in of crop residue, either from the previous season or specially grown crop, is often considered a mitigation option. Nevertheless, there is concern that fresh organic matter (FOM) might accelerate decomposition of existing organic. This study assesses effects of FOM on the emissions of CO₂, methane (CH₄) and N₂O in a cultivated peatland. A mesocosm experiment was carried out using intact cores with added FOM and manipulated water table (WT), -20 and -50 cm.

The results show there is an effect of both WT and FOM on emissions. CO₂, CH₄, and N₂O emissions differ in the different WT treatments. The -20 cm cores produced more methane than the -50 cm.  It is evident that leaving crop residue and then ploughing it in does not have the desired effect as it led to increased emissions.

How to cite: Musarika, S., Jones, D., Chadwick, D., McNamara, N., and Evans, C.: Effects of crop residue on carbon dioxide, methane and nitrous oxide emissions on cultivated peat soils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11148, https://doi.org/10.5194/egusphere-egu2020-11148, 2020.

Viruses play a crucial and underexplored role in soil microbial ecosystems, but soil viral ecology has focused exclusively on DNA viruses. The role of RNA viruses in soil ecosystems has therefore been largely overlooked, despite their significant impact on public health and food security. Here, we report the first ever study to apply viromics to survey soil RNA viral communities from five sites along an altitudinal primary productivity gradient in the UK. We identified over 3,000 viral sequences, of which over half were unclassified, and newly identified viruses were placed in a global context by the phylogenetic comparison of their RNA-dependent RNA polymerase genes. Unlike DNA viral communities, the RNA viromes were heavily dominated by viruses of eukaryotes, including pathogens of plants, fungi, vertebrates and invertebrates. Sampling sites showed minimal similarity in viral community composition, suggesting that we have just scratched the surface of soil RNA viral diversity. Wider sequencing efforts and method development are required to further explore soil RNA viromes and understand their ecological function; however, this study represents an important step towards the characterisation of soil viral communities and interactions with their microbial hosts, which will provide a more holistic view of the biology of economically and ecologically important soils.

How to cite: Hillary, L., Adriaenssens, E., Jones, D., and McDonald, J.: Life, but not as we know it: exploring RNA viral diversity in soils through viromics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19732, https://doi.org/10.5194/egusphere-egu2020-19732, 2020.

The configuration of a biologically active and fertile substrate consisting mainly of Martian regolith to facilitate the growth of edible plants during long-term manned missions to Mars constitutes one of the main challenges in spatial research. Regolith amendment with compost derived from recycled crew effluent crop waste generated by bioregenerative life support systems constitutes a substrate that may contribute to upgrade crew autonomy and long-term survival in space. In this context, the present work aimed to: i) study the geochemical and mineralogical composition of MMS-1 Mars simulant and the physicochemical and hydraulic properties of mixtures obtained by mixing MMS-1 and green compost at varying rates (0:100, 30:70, 70:30, 100:0; v:v); ii) evaluate the potential use of MMS-1 as growing medium of two lettuce cultivars; iii) assess how compost addition may impact on sustainability of space agriculture exploiting local resources. MMS-1 is a coarse-textured alkaline substrate consisting mostly of plagioclase, amorphous material and, to a lesser extent, zeolite, hematite and smectites. Although it can be source of nutrients, it lacks of organic matter, nitrogen (N), phosphorus (P) and sulphur (S), which may be supplied by compost. Both lettuce (Lactuca sativa L.) cultivars were able to grow on all mixtures for 19 days under fertigation. Red Salanova lettuce produced a statistically-greater dry biomass, leaf area and number than green Salanova. Leaf area and plant dry biomass were higher on 30:70 simulant/compost mixture. The shoot/root ratio of plants decreased as simulant in growth substrate increased. Lack of biological fertility and possible salt stress negatively impacted on plants grown in non-amended simulant. Our results show that it is possible to grow crops in Martian simulants adequately amended and fertilized. However, many remaining issue warrant further investigation concerning the dynamics of compost production, standardization of supply during long-term manned missions and representativeness of simulants to real Martian regolith.

How to cite: Adamo, P., Vingiani, S., Palladino, M., El-Nakhel, C., Duri, L. G., Pannico, A., Rouphael, Y., De Pascale, S., and Caporale, A. G.: Characterisation of Martian soil simulant MMS-1 in mixture with green compost for future sustainable space agriculture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6098, https://doi.org/10.5194/egusphere-egu2020-6098, 2020.

In recent years deforestation of the Gran Chaco of Argentina has increased dramatically to make way for agricultural expansion.  Extensive cattle ranching in particular is widespread across the country, and in the Chaco region of the north west much of the natural vegetation has been cleared for beef and crop production.  The effects of forest clearance and grazing over time on soil carbon dynamics are unclear, with some evidence suggesting that soil carbon can to some extent recover under low intensity grazing practices, whilst others find that conversion to pasture followed by years of grazing consistently decreases soil carbon stocks.  This study investigates the effects of land use change from forest to pasture over time on soil carbon stocks in the dry Chaco of north western Argentina, through the measurement of biological, physical and chemical variables within the soil.  The hypothesis leading to this work is the key idea that livestock grazing can promote the accumulation of carbon in the soil over time through processes such as the stimulation of root growth of pasture grasses.  In turn, increased carbon inputs can lead to net carbon sequestration, with great potential to mitigate the greenhouse gas emissions of the livestock sector.  Using a chronosequence experimental design, destructive soil samples were taken from reference forest patches and pastures of 0-5, 10-15 and >20 years since deforestation and were tested for carbon, nitrogen, and phosphorus contents, root biomass, pH, electrical conductivity and texture. The research aims to investigate and explain the carbon dynamics of pastures in the years following deforestation, identify potential biotic and abiotic drivers of such dynamics, and predict potential future changes in soil carbon stocks.

How to cite: Durcan, R., Rufino, M., Ostle, N., Banegas, N., and Viruel, E.: Effects of land use change and grazing on soil carbon dynamics in the semi arid Chaco, Argentina, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20607, https://doi.org/10.5194/egusphere-egu2020-20607, 2020.

LA Kemp, Supervisors: A. Karley, A. Bennett, A. Taylor, N. McNamara, E.J Sayer

Short – rotation woody perennials such as Populus and Salix are often selected for bioenergy crops in temperate climates. In conjunction with providing a renewable crop, bioenergy crops can improve carbon storage in previously degraded soils and associate with beneficial mycorrhizal fungi. Applying nitrogen fertilizers to bioenergy crops can increase yield and carbon sink but may also increase CO2 emissions through increased soil respiration and N2O through increased microbial activity which alter population and community dynamics.

Changing environmental conditions due to climate change such as prolonged droughting and increasing intensity of rewetting are also impacting plant-soil interactions. However, there are gaps in the understanding of the mechanisms responsible for plant responses to changing abiotic conditions. Therefore, the scale of future carbon cycling, CH4 and N2O emissions by temperate tree species are still very unclear.

To address this my experiment, focuses on two temperate tree species used in bioenergy production known to associate with mycorrhizal fungi. The study will run over two growing seasons, using a randomized block design with four fungal treatments, four nutrient treatments and then implementing two abiotic treatments during the second growing season. I aim to determine how soil nutrient availability influences: i) plant – mycorrhiza associations, ii) plant carbon cycling and storage, iii) soil respiration rates, iv) plant and soil GHG emission rates. v) carbon cycling and GHG emissions under different climate controls.

How to cite: Kemp, L.-A.: The influence of soil fertility on carbon cycling and storage in temperate tree bioenergy crops , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3686, https://doi.org/10.5194/egusphere-egu2020-3686, 2020.

The application of digestate from anaerobic digestion to grassland soils is of growing interest as an agricultural practice. However, significant uncertainties surrounding the potential impacts of digestate application on processes associated with the soil microbial community remain, particularly for processes governing Carbon Use Efficiency (CUE) and the broader soil C cycle. In this research, we examined how the C:N stoichiometry of digestate and the nutrient status of soil influenced the impact of digestate application on the soil C cycle.  

Three fractions of digestate (whole [WD], solid [SD] and liquid [LD]), spanning a range of C:N, were each applied to two soils of contrasting starting nutrient status (high and low) and compared to unamended controls (Ctr). Two short-term incubations, each lasting seven days, were undertaken. In the first, applications of WD, SD and LD each achieved the same total N input to soils. In the second, digestate applications were adjusted to provide consistent total C input to soils. In each incubation, CO₂-C efflux, microbial biomass C (C_micro) and pH were determined.  

In each of the two incubations, the application of digestate significantly increased cumulative CO₂-C efflux compared to control soils. However, the precise effect of digestate application varied between the two incubations and with both soil nutrient status and digestate fraction. Microbial biomass C was largely unchanged by the treatments in both incubations. During the first incubation, soil pH decreased substantially following each digestate treatment in both soil types. A similar pattern was observed within the second incubation in the high nutrient soil. However, in contrast, soil pH increased substantially following LD and WD application to the low nutrient soil in the second incubation. Varying CUE responses are likely to be observed following the application of digestate to agricultural soils, dependent on digestate fraction, C:N ratio of the digestate, and the initial soil nutrient status. Therefore, digestate application rates and soil management must be carefully planned in order to avoid adverse impacts of digestate application to land. 

How to cite: Cattin, M., Stutter, M., Lag-Brotons, A., Wadley, P., Semple, K. T., Parry, C., and Surridge, B. W. J.: Anaerobic Digestate Fraction and Nutrient Stoichiometry Significantly Influence the Carbon Cycle in Grassland Soils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19459, https://doi.org/10.5194/egusphere-egu2020-19459, 2020.

Our global climate continues to change, and with that comes the change of our soil climate. Reports by the IPCC indicate annual increases in prolonged rainfall events within temperate climates; thus exacerbating widespread autumn/winter waterlogged conditions within in the years to come. For our soils, this means the development of anaerobic systems as wetland areas and frequent flooding become more common. Reducing systems like these are capable of facilitating conditions in which alternative oxidation states of the vital elements needed for soil health present themselves. The change of our soil climate is rarely considered when attempting to understand how phosphorus is cycled and how it might be affected in an alternative environment. Existing knowledge from the marine sector demonstrates that a low oxidation state group of compounds known as phosphonates (+3) are successfully utilised by micro-organisms instead of phosphate (+5) as their phosphorus source; thus demonstrating that the phosphorus biogeochemical cycle is much more complex than previously regarded. In the case of the soil environment, there is a large quantity of inaccessible phosphorus present that might be utilised through similar microbial mechanisms when considering a reducing system. The aim of this research is to alter the understanding of global phosphorus cycling and additionally of ecosystem phosphorus limitation. This is done by assessing the capabilities of certain biological species to process phosphorus in alternative oxidation states, highlighting the importance of reduced phosphorus compounds on the global redox cycle.

How to cite: Kehler, A., Blackwell, M., Haygarth, P., and Tamburini, F.: The utilisation of Amino methyl phosphonic acid by soil micro-organisms as a phosphorus nutrient source , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2212, https://doi.org/10.5194/egusphere-egu2020-2212, 2020.

The UK has a legacy of onshore oil and gas wells. Aging extraction wells, with deteriorating cap engineering, may act as preferential pathways for gas seepage from the sub-surface. Seeps from hydrocarbon reservoirs are predominately composed of potent greenhouse gases, such as methane and carbon dioxide. Shifts in the soil microbial community are potential indicators of alkane gases rising from the sub-surface. Therefore, soil microbial community change could be used as a tool for monitoring aging, legacy wells, for gas seepage. An increased abundance in bacteria that metabolise methane (methanotrophs), or, C3-C4 alkanes (propanotrophs/butanotrophs) should be correlated with an increased flux of those gases, thereby indicating the presence of a seep.

In the South-East of the Auvergne-Rhône-Alpes region of France, there are several natural-gas analogue macro-seeps where the soil microbial community is potentially interacting with increased alkane fluxes. A well characterised natural gas seepage site was visited, and soil samples were collected for DNA analysis. Surface gas flux measurements and soil-pore gas concentrations (at 1 metre depth) were collected at the same sampling locations by BGRM involved in the ERA-ACT funded Subsurface Evaluation of Carbon capture and storage and Unconventional Risk (SECURe) project. The abundance of alkanotrophs within the bacterial community was explored using quantitative-PCR assays of the key genes used in alkane metabolism. DNA was used in qPCR assays to estimate the proportion of methane monooxygenase and butane/propane oxidising genes within the total bacterial community (using 16S as a proxy). The in-field measurements of gases were contrasted with the relative abundance of methanotrophs and propanotrophs/butanotrophs.

Preliminary results suggest an increased abundance of methanotrophs above soils with higher pore gas concentrations of methane. These methanotrophs have oxidised the rising methane producing small isolated anomalies of increased methane flux at the surface. This suggests that methanotrophs might be a tool for locating soils with an increased methane concentration.

How to cite: Bott, T., Gregory, S., Shaw, G., and Palumbo-Roe, B.: Soil Microbial Indicators of Alkane Flux around a Natural Gas Seep , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18572, https://doi.org/10.5194/egusphere-egu2020-18572, 2020.

The use of phosphorus (P) fertilizer has been one of the defining contributors to productive agriculture since the green revolution during the middle of the last century. However, these increased yields have come at the cost of dependency upon the declining resources of P rock reserves and eutrophication of water bodies downstream. In this context, it is important to understand the long-term effects of these P fertilizer additions on soil chemistry over ~50 years in order explain past and current patterns in fertilizer usage and so to better inform future soil management.

We tested the hypothesis that phosphorus forms and availability in mixed use (arable and grazed) agricultural soil have changed over a period of 50 to 80 years of agricultural intensification. Spatially matched samples of soil from 34 agricultural sites in North East (NE) Scotland were collected at two timepoints. The first samples were taken between 1951 and 1981 and in all cases the resampling took place in the autumn of 2017. The soils sampled were representative of agricultural soils in NE Scotland.

The hypothesis was tested by employing a range of soil tests on the ‘old’ and ‘new’ time points.  These included water extraction for inorganic and organic P, nitrate and ammonium and dissolved organic carbon, acid ammonium oxalate extraction to investigate the soil P exchange complex and NaOH-EDTA extraction as a strong alkaline extractant which preserves organic P forms. Analysis by ³¹P NMR was conducted on the NaOH-EDTA extracts from 5 pairs of samples, to investigate the organic P chemistry of in greater detail.

Phosphorus concentrations for stronger extractants (NaOH-EDTA, acid ammonium oxalate) did not increase significantly (P<0.05) over time. However, water extraction results showed increases in total P (P<0.01) and inorganic P but decreases in organic P. Additionally, analysis by ³¹P NMR detected changes between timepoints in α-glycero-phosphate and pyrophosphate.

These results indicate that differences in the various chemical forms of P present in soil between the timepoints can be detected many decades apart. This indicates changes in the functioning of the P cycle in these soils under intensive agricultural land use over time. Knowledge of the P-cycling response of soils under agricultural land-use over decades provides an opportunity to understand changes in soil nutrient concentrations, balances and availability and inform studies seeking to improve the sustainable management of soil fertility.

How to cite: Tweedie, A., Haygarth, P. M., Edwards, A., Lilly, A., Baggaley, N., and Stutter, M.: Phosphorus chemical changes under soils over a period of agricultural intensification, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18579, https://doi.org/10.5194/egusphere-egu2020-18579, 2020.

Urine patches in grassland ecosystems present unique environments where extreme nitrogen (N) loading occurs. This results in N losses into the atmosphere or leaching from soil. N losses vary due to climate conditions, soil conditions, and management practices. However, we do not fully understand how these factors influence N cycling and nitrous oxide (N₂O) emissions from urine patches. Much of the current literature on urine patch N cycling has focused on typical lowland agricultural systems. Very little work has explored other grazing systems, such as upland farming which is conducted across much of Wales. We have investigated this by using a catena sequence crossing both upland and lowland agricultural grazing systems. The range of soil types allowed us to explore how N₂O emissions and N losses vary under different conditions. Here we report on both a laboratory incubation and a mesocosm experiment examining these issues. This work should help to fill the knowledge gap around how emissions from urine patches could vary between UK uplands and lowlands. We hope to improve understanding of N losses and provide more realistic, regional, and accurate emission factors for upland farming systems.

How to cite: Hunt, D., Jones, D., Cardenas, L., and Chadwick, D.: Exploring nitrogen losses from urine patches between upland and lowland grazing systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9843, https://doi.org/10.5194/egusphere-egu2020-9843, 2020.

Food habits or more generally food consumption, especially agro-food products, have always been linked to the territory of production. The Sorrento lemon (Citrus limon (L.) Burm. f. cv. Ovale di Sorrento), is known for its characteristic cultivation on terraces in Sorrento peninsula of Campania (south Italy). In this environment, the peculiar soil and climatic features and the traditional cultivation on terraces have contributed not only to high-quality lemon productions but also to protect the landscape. Indeed, in terms of soil and climatic features, the Sorrento peninsula is very heterogeneous. The geographical conformation of the territory, along with the rainfall increase with elevation and in more inland areas, leads to different microclimates and habitats, even at a very small scale.  Main aim of this work was to develop a chemometric discriminant model to authenticate and track Sorrento lemons at a small geographical scale by multi-element fingerprinting and Linear Discriminant Analysis (LDA) in order to protect the PGI lemon from lemons of other geographical origins. The variability of the total and bioavailable mineral contents in soil (top and subsoil) and their relationship with lemon juices were analysed. The multi-element fingerprinting of different areas are different for mineralogical and geochemical composition. The array of inorganic elements of agrofoods is greatly affected by the soil features, such as mineralogy, pH, moisture, and organic constituents. The LDA model was developed and cross-validated with the cultivar “Ovale di Sorrento”. External validation with other cultivars (Femminello Zagara Bianca, Femminello Siracusano 2KR, Femminello Sfusato Amalfitano, Femminello Adamo, and Femminello Cerza), grown in the same areas, was carried out. The LDA model was applied to 102 samples of “Ovale di Sorrento” lemons, cross-validated (96.08% of correct classification) and validated with external validation of 67 lemons juices from other cultivars (94.03% of correct classification) according to geographical origins. Pearson correlation analysis of the total and bioavailable element content of cultivation soils (top and subsoil) and lemons juices was performed.

How to cite: Ruggiero, L., Fontanella, M. C., Amalfitano, C., Beone, G. M., Di Vaio, C., and Adamo, P.: Geochemical fingerprinting of lemon juices and cultivation soils for authentication and traceability of geographical provenience, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20947, https://doi.org/10.5194/egusphere-egu2020-20947, 2020.

Although fine-grained sediment (FGS) is a natural component of river systems, increased fluxes can impact FGS levels to such an extent they cause detrimental, irreversible changes in the way rivers function intensifying flood risk and negatively affecting water quality.

Previous catchment scale studies indicate there is no simple link between areas of sediment loss and the organic carbon (OC) load in waterways; areas with a high soil loss rate may not contribute most sediment to the rivers and areas that contribute the most sediment may not contribute the most OC. Anthropogenic and climate changes can accelerate soil erosion and the role of soil OC transported by erosional processes in the fluxes of C between land, water and atmosphere is still debated. Tracing sediment pathways, likely depositional areas and connections to streams leads to better assumptions about control processes and better estimation of OC fluxes.

In this innovative study OC fingerprinting of sediment reaching a catchment’s waterbodies is combined with OC stock and erosion modelling of the terrestrial catchment. Initial results show disconnect between catchment OC loss erosion modelling and fingerprinting results, which could be due to failure to model connectivity between the land and river channel. The current soil erosion model RUSLE (Revised Universal Soil Loss Equation) calculates only the spatial pattern of mean annual soil erosion rates. Using the WaTEM SEDEM model, which in includes routing (and possible en route deposition) of eroded sediments to river channels, we aim to determine the dominant source of OC within catchment streams by identification of both the land-use specific areas with the highest OC loss and the transport pathways between the sources and river channel.

How to cite: Wiltshire, K., Waine, T., Grabowski, B., Glendell, M., Addy, S., Baggaley, N., Thornton, B., Meersmans, J., and Napier, F.: Sediment origins across the terrestrial-aquatic continuum: climate threat mitigation and promotion of water quality, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2637, https://doi.org/10.5194/egusphere-egu2020-2637, 2020.