Browsing by Author "Girkin, Nicholas T."

Now showing 1 - 20 of 26
  • Thumbnail Image
    ItemOpen Access
    Assessing the impact of voluntary certification schemes on future sustainable coffee production
    (MDPI, 2024-07-03) Jones, Katharine; Njeru, Ezekiel Mugendi; Garnett, Kenisha; Girkin, Nicholas T.; This research was supported by the Natural Environmental Research Council (NE/X001687/1 and NE/X001679/1).; Natural Environmental Research Council
    Coffee production faces major sustainability issues and consumers increasingly look to choose certified coffee as awareness grows. While consumers’ understanding of sustainability issues is limited, independent voluntary certification schemes such as Fairtrade, Rainforest Alliance, and certified organic—three high-profile schemes—can play a role in future-proofing coffee production through standard-setting. These schemes can also inform consumers about sustainability issues from economic, environmental, and social perspectives, thus driving up demand for sustainably grown coffee, and supporting an enabling environment for farmers and coffee-producing countries to improve the status quo. Sustainably grown coffee ensures that farmers sustain production while protecting the environment and the income that farmers rely on to maintain their livelihood. Based on a thematic analysis and synthesis of previous studies, this paper examines the social, economic, and environmental effects of voluntary certification schemes for coffee production. It evaluates the current state of coffee production and explores how certification schemes can be effective in encouraging more sustainable practices among producers. Three major voluntary certification schemes are evaluated to identify the impacts on producers, including key barriers and enablers to comply with sustainability standards and to determine how fit-for-purpose certification schemes are in assuring future sustainable coffee production.
  • Thumbnail Image
    ItemOpen Access
    The contribution of natural burials to soil ecosystem services: review and emergent research questions
    (Elsevier, 2023-11-22) Pawlett, Mark; Girkin, Nicholas T.; Deeks, Lynda K.; Evans, Daniel L.; Sakrabani, Ruben; Masters, Peter; Garnett, Kenisha; Marquez-Grant, Nicholas
    The modern funeral industry faces many environmental risks and challenges, such as the use of sustainable materials for coffins, the release of potentially damaging materials and organisms to the soil and groundwater, and reduced space available for cemeteries. “Natural burial” proposes an alternative and more sustainable funeral practice, omitting the use of preservatives that inhibit body decomposition, thus proposing to reduce environmental degradation and benefit soil ecosystem services. This study conducted a literature review to identify proposed risks and benefits of “natural” compared to “traditional” burial practices, identifies knowledge gaps, and proposes further research questions. The approach was multidisciplinary, including literature from soil, environmental, forensic, and archaeological sciences, and the Humanities. Results identified that here are some clear environmental benefits to natural burial, such as habitat creation and aboveground biodiversity. However, there is a substantial deficit of research that compares the unseen risks and benefits of natural burial practice. Multiple potential risk factors include: (i) groundwater contaminated with biochemical products of decomposition, pathogens, and pharmaceutical products, (ii) atmospheric emissions, including greenhouse gases (CO2, CH4, N2O). There is also a deficit of information related to the release of cadaver decomposition products to soil ecological processes. More detailed scientific research is required to identify the risks and benefits of funeral options, thus develop fit for purpose regulations and legislation and to describe the cultural incentives for natural burial. This paper identifies key areas of research required to understand and mitigate the potential environmental and cultural implications of human burial practices.
  • Thumbnail Image
    ItemOpen Access
    Current knowledge on the Cuvette Centrale peatland complex and future research directions
    (C I R A D, 2021-12-01) Biddulph, George Elliot; Bocko, Yannick Enock; Bola, Pierre; Crezee, Bart; Dargie, Greta C.; Emba, Ovide; Georgiou, Selena; Girkin, Nicholas T.; Hawthorne, Donna; Jovani-Sancho, A. Jonay; Kanyama, Joseph; Mampouya, Wenina Emmanuel; Mbemba, Mackline; Sciumbata, Matteo; Tyrrell, Genevieve
    The Cuvette Centrale is the largest tropical peatland complex in the world, covering approximately 145,000 km2 across the Republic of Congo and the Democratic Republic of Congo. It stores ca. 30.6 Pg C, the equivalent of three years of global carbon dioxide emissions and is now the first trans-national Ramsar site. Despite its size and importance as a global carbon store, relatively little is known about key aspects of its ecology and history, including its formation, the scale of greenhouse gas flows, its biodiversity and its history of human activity. Here, we synthesise available knowledge on the Cuvette Centrale, identifying key areas for further research. Finally, we review the potential of mathematical models to assess future trajectories for the peatlands in terms of the potential impacts of resource extraction or climate change.
  • Thumbnail Image
    ItemOpen Access
    Evaluating agroecological farming practices
    (DEFRA, 2023-02-20) Burgess, Paul J.; Redhead, John; Girkin, Nicholas T.; Deeks, Lynda K.; Harris, Jim A.; Staley, Joanna T.
    There are a range of definitions for agroecologically-related farming systems and practices. In brief, organic farming places strong restrictions on inputs, agroecological analyses often focus on principles, and regenerative farming typically emphasises the enhancement of soil health and the diversity of agricultural and wild species at a farm-scale. Perhaps surprisingly the role of agroecological systems in reducing net greenhouse gas emissions from food and farming is implicit rather than explicit. Despite some literature contrasting agroecological and technical approaches, many authors indicate that the desirability of farming practices should be determined by their impact at the appropriate scale. Sustainable intensification has been defined as maintaining or enhancing agricultural production while enhancing or maintaining the delivery of other ecosystem services. Approaches such as the Global Farm Metric and LEAF Marque Certification can support the integrated assessment of 12 groupings of attributes at a farm-scale covering inputs and outputs, and environmental and social impacts. In this report we reviewed the following 16 practices: crop rotations, conservation agriculture, cover crops, organic crop production, integrated pest management, the integration of livestock to crop systems, the integration of crops to livestock systems, field margin practices, pasture-fed livestock systems, multi-paddock grazing, organic livestock systems, tree crops, tree-intercropping, multistrata agroforestry and permaculture, silvopasture, and rewilding.
  • Thumbnail Image
    ItemOpen Access
    Evidence Project Final Report: Evaluating the productivity, environmental sustainability and wider impacts of agroecological compared to conventional farming systems
    (DEFRA, 2023-12-31) Burgess, Paul J.; Staley, Joanna T.; Hurley, Paul D.; Rose, David Christian; Redhead, John R.; McCracken, Morag E.; Girkin, Nicholas T.; Deeks, Lynda K.; Harris, Jim A.
    Agriculture is a major cause of greenhouse gas (GHG) emissions, biodiversity loss, and pollution. Agroecological and regenerative farming have been advocated as alternative approaches that may have fewer negative (or even net positive) environmental impacts than conventional agriculture at farm- and landscape-scales, leading to considerable interest in these approaches (Newton et al. 2020; Bohan et al. 2022; Prost et al. 2023). This report forms the third part of a Defra-funded project Evaluating the productivity, environmental sustainability and wider impacts of agroecological and regenerative farming systems compared to conventional systems. The first part of this project was a rapid evidence review of agroecological and regenerative farming systems and their impacts (Burgess et al. 2023), and the second reported interview findings to examine farmer and stakeholder perspectives on barriers and enablers in agroecological and regenerative farming (Hurley et al. 2023). This third part of the project characterised the current research capability in agroecology and regenerative farming, and explored the potential role of a new ‘living lab’ trial network.
  • Thumbnail Image
    ItemOpen Access
    Examination of prolonged dry cold storage and hydration lengths during the process stage on cut roses vase life
    (Cranfield University, 2024-03) Hosseini, Sara; Girkin, Nicholas T.; Alamar, MariCarmen; Veheecke-Vaessen, Carol
    Cut flowers have found an important role in human life, so market demand and cultivation are increasing. As cut flowers are highly perishable, it is important to extend their vase life to address sustainability challenges, avoid waste of natural resources, reduce carbon footprint and gain customer satisfaction. In the UK approximately 90% of cut flowers are imported (ca. 30% represent cut roses) and kept under dry cold conditions. During periods of high consumer demand, flowers may experience prolonged dry storage time compared to the rest of the year; this can affect vase life negatively. There are few studies mimicking real supply chain scenarios and, therefore, we simulate it for cut roses in the UK to examine the impacts of prolonged dry cold storage and hydration lengths on rose vase life in two separate experiments. The first study investigated drying lengths (24, 48, 72, and 96 hours at 5ºC) on vase life of two varieties: ‘Revival Sweet’ and ‘Golden Smile’. Interaction between drying (96 and 168 hours) and hydration solution usage time (0, 12, 24 and 48 hours) on ‘Revival Sweet’ was examined in the second experiment. In general, shorter drying times resulted in the longest vase life with fewer signs of physical damage (bent neck and damaged flower). In colour examination, no clear relationship between L*, C* h°, drying and hydration lengths was seen which may be because of the pink colour of ‘Revival Sweet’. Expanding hydration length improved solution uptake, reduced the pH, eliminated bacterial growth in vase water, preserved the sugar source and postponed senescence. When flowers were kept dry for 168 hours, hydration for 48 hours helped them show less than 50% damaged flowers and just approximately 30% bent necks after 18 days. In conclusion, during peak period, hydration for more than 24 hours is suggested to eliminate the negative impacts of prolonged dry storage.
  • Thumbnail Image
    ItemOpen Access
    Expert assessment of future vulnerability of the global peatland carbon sink
    (Nature Publishing Group, 2020-12-07) Loisel, J.; Gallego-Sala, A. V.; Amesbury, M. J.; Magnan, G.; Girkin, Nicholas T.
    The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert elicitation, we define and quantify the leading drivers of change that have impacted peatland carbon stocks during the Holocene and predict their effect during this century and in the far future. We also identify uncertainties and knowledge gaps in the scientific community and provide insight towards better integration of peatlands into modelling frameworks. Given the importance of the contribution by peatlands to the global carbon cycle, this study shows that peatland science is a critical research area and that we still have a long way to go to fully understand the peatland–carbon–climate nexus
  • Thumbnail Image
    ItemOpen Access
    Hydroclimatic vulnerability of peat carbon in the central Congo Basin
    (Springer, 2022-11-02) Garcin, Yannick; Schefuß, Enno; Dargie, Greta C.; Girkin, Nicholas T.
    The forested swamps of the central Congo Basin store approximately 30 billion metric tonnes of carbon in peat1,2. Little is known about the vulnerability of these carbon stocks. Here we investigate this vulnerability using peat cores from a large interfluvial basin in the Republic of the Congo and palaeoenvironmental methods. We find that peat accumulation began at least at 17,500 calibrated years before present (cal. yr BP; taken as AD 1950). Our data show that the peat that accumulated between around 7,500 to around 2,000 cal. yr BP is much more decomposed compared with older and younger peat. Hydrogen isotopes of plant waxes indicate a drying trend, starting at approximately 5,000 cal. yr BP and culminating at approximately 2,000 cal. yr BP, coeval with a decline in dominant swamp forest taxa. The data imply that the drying climate probably resulted in a regional drop in the water table, which triggered peat decomposition, including the loss of peat carbon accumulated prior to the onset of the drier conditions. After approximately 2,000 cal. yr BP, our data show that the drying trend ceased, hydrologic conditions stabilized and peat accumulation resumed. This reversible accumulation–loss–accumulation pattern is consistent with other peat cores across the region, indicating that the carbon stocks of the central Congo peatlands may lie close to a climatically driven drought threshold. Further research should quantify the combination of peatland threshold behaviour and droughts driven by anthropogenic carbon emissions that may trigger this positive carbon cycle feedback in the Earth system.
  • Thumbnail Image
    ItemOpen Access
    Identifying sustainable nitrogen management practices for tea plantations
    (MDPI, 2022-01-14) Rebello, Rhys; Burgess, Paul J.; Girkin, Nicholas T.
    Tea (Camellia sinensis L.) is the most widely consumed beverage in the world. It is mostly grown in the tropics with a heavy dependence on mineral nitrogen (N) fertilisers to maintain high yields while minimising the areas under cultivation. However, N is often applied in excess of crop requirements, resulting in substantial adverse environmental impacts. We conducted a systematic literature review, synthesising the findings from 48 studies to assess the impacts of excessive N application on soil health, and identify sustainable, alternative forms of N management. High N applications lead to soil acidification, N leaching to surface and groundwater, and the emission of greenhouse gases including nitrous oxide (N2O). We identified a range of alternative N management practices, the use of organic fertilisers, a mixture of organic and inorganic fertilisers, controlled release fertilisers, nitrification inhibitors and soil amendments including biochar. While many practices result in reduced N loading or mitigate some adverse impacts, major trade-offs include lower yields, and in some instances increased N2O emissions. Practices are also frequently trialled in isolation, meaning there may be a missed opportunity from assessing synergistic effects. Moreover, adoption rates of alternatives are low due to a lack of knowledge amongst farmers, and/or financial barriers. The use of site-specific management practices which incorporate local factors (for example climate, tea variety, irrigation requirements, site slope, and fertiliser type) are therefore recommended to improve sustainable N management practices in the long term.
  • Thumbnail Image
    ItemOpen Access
    Immediate environmental impacts of transformation of an oil palm intercropping to a monocropping system in a tropical peatland
    (International Mire Conservation Group, International Peat Society, 2022-04-14) Dhandapani, Selva; Girkin, Nicholas T.; Evers, Stephanie; Ritz, Karl; Sjögersten, Sofie
    The expansion of oil palm plantations is one of the greatest threats to carbon-rich tropical peatlands in Southeast Asia. More than half of the oil palm plantations on tropical peatlands of Peninsular Malaysia are smallholder-based, which typically follow varied cropping systems, such as intercropping. In this case study, we compare the immediate biogeochemical impacts of conversion of an oil palm and pineapple intercropping to an oil palm monocropping system. We also assess how these changes affect the subsequent temperature sensitivity of greenhouse gas (GHG) production. We found that peat bulk density is unchanged, while organic matter content, pH and temperature is slightly yet significantly altered after conversion from oil palm intercropping to monocropping. Both in-situ and ex-situ CO2 emissions and temperature sensitivity of CO2 and CH4 production did not significantly vary between conversion stages; however, in-situ CO2 emissions in monocropping system exhibited a unique positive correlation with moisture. The findings show that some of the defining peat properties, such as bulk density and organic matter content, were mostly conserved immediately after conversion from intercropping to oil palm monocropping. However, there were signs of deterioration in other functional relationships, such as significantly greater CO2 emissions observed in the wet season to that of the dry season, showing moisture limitation to CO2 emissions in monocropping, postconversion. Nevertheless, there is a need for further research to identify the long-term impacts, and also the sustainability of intercropping practices in mature oil palm plantations for the benefit of these peat properties.
  • Thumbnail Image
    ItemOpen Access
    Linking long‑term soil phosphorus management to microbial communities involved in nitrogen reactions
    (Springer, 2022-02-24) O'neill, R. M.; Duff, A. M.; Brennan, Feargal Peter; Gebremichael, A. W.; Girkin, Nicholas T.; Lanigan, G. J.; Krol, D. J.; Wall, D. P.; Renou‑Wilson, F.; Müller, C.; Richards, K. G.; Deveautour, C.
    The influence of soil phosphorous (P) content on the N-cycling communities and subsequent effects on N2O emissions remains unclear. Two laboratory incubation experiments were conducted on soils collected from a long-term (est. 1995) P-addition field trial sampled in summer 2018 and winter 2019. Incubations were treated with a typical field amendment rate of N as well as a C-amendment to stimulate microbial activity. Throughout both incubations, soil subsamples were collected prior to fertiliser amendment and then throughout the incubations, to quantify the abundance of bacteria (16S rRNA), fungi (ITS) and Thaumarcheota (16S rRNA) as well as functional guilds of genes involved in nitrification (bacterial and archaeal amoA, and comammox) and denitrification (nirS, nirK, nosZ clade I and II) using quantitative PCR (qPCR). We also evaluated the correlations between each gene abundance and the associated N2O emissions depending on P-treatments. Our results show that long-term P-application influenced N-cycling genes abundance differently. Except for comammox, overall nitrifiers’ genes were most abundant in low P while the opposite trend was found for denitrifiers’ genes. C and N-amendments strongly influenced the abundance of most genes with changes observed as soon as 24 h after application. ITS was the only gene correlated to N2O emissions in the low P-soils while microbes were mostly correlated to emissions in high P, suggesting possible changes in the organisms involved in N2O production depending on soil P-content. This study highlights the importance of long-term P addition on shaping the microbial community function which in turn stimulates a direct impact on the subsequent N emissions.
  • Thumbnail Image
    ItemOpen Access
    Long-term zero-tillage enhances the protection of soil carbon in tropical agriculture
    (Wiley, 2021-03-27) Cooper, Hannah V.; Sjögersten, Sofie; Lark, Richard M.; Girkin, Nicholas T.; Vane, Christopher H.; Calonego, Juliano C.; Rosolem, Ciro; Mooney, Sacha J.
    Contrasting tillage strategies not only affect the stability and formation of soil aggregates but also modify the concentration and thermostability of soil organic matter associated with soil aggregates. Understanding the thermostability and carbon retention ability of aggregates under different tillage systems is essential to ascertain potential terrestrial carbon storage. We characterised the concentration and thermostability of soil organic carbon (SOC) within various aggregate size classes under both zero and conventional tillage using novel Rock‐Eval pyrolysis. The nature of the pore systems was visualised and quantified by X‐ray Computed Tomography to link soil structure to organic carbon preservation and thermostability. Soil samples were collected from experimental fields in Botucatu, Brazil, which had been under zero‐tillage for 2, 15 and 31 years, along with adjacent fields under conventional tillage. Soils under zero‐tillage significantly increased pore connectivity whilst simultaneously decreasing inter‐aggregate porosity, providing a potential physical mechanism for protection of soil organic carbon in the 0‐20 cm soil layer. Changes in the soil physical characteristics associated with the adoption of zero‐tillage resulted in improved aggregate formation compared to conventionally tilled soils, especially when implemented for at least 15 years. In addition, we identified a chemical change in composition of organic carbon to a more recalcitrant fraction following conversion to zero‐tillage, suggesting aggregates were accumulating rather than mineralising soil organic carbon. These data reveal profound effects of different tillage systems upon soil structural modification, with important implications for the potential of zero‐tillage to increase carbon sequestration compared to conventional tillage.
  • Thumbnail Image
    ItemOpen Access
    Mapping peat thickness and carbon stocks of the central Congo Basin using field data
    (Springer Nature, 2022-07-21) Crezee , Bart; Dargie, Greta C.; Ewango, Corneille E. N.; Mitchard , Edward T. A.; Emba B, Ovide; Kanyama T, Joseph; Bola, Pierre; Ndjango, Jean-Bosco N.; Girkin, Nicholas T.; Bocko, Yannick E.; Ifo, Suspense A.; Hubau , Wannes; Seidensticker , Dirk; Batumike, Rodrigue; Imani , Gérard; Cuní-Sanchez, Aida; Kiahtipes , Christopher A.; Lebamba, Judicaël; Wotzka, Hans-Peter; Bean, Hollie; Baker , Timothy R.; Baird , Andy J.; Boom, Arnoud; Morris , Paul J.; Page, Susan E.; Lawson, Ian T.; Lewis , Simon L.
    The world’s largest tropical peatland complex is found in the central Congo Basin. However, there is a lack of in situ measurements to understand the peatland’s distribution and the amount of carbon stored in it. So far, peat in this region has been sampled only in largely rain-fed interfluvial basins in the north of the Republic of the Congo. Here we present the first extensive field surveys of peat in the Democratic Republic of the Congo, which covers two-thirds of the estimated peatland area, including from previously undocumented river-influenced settings. We use field data from both countries to compute the first spatial models of peat thickness (mean 1.7 ± 0.9 m; maximum 5.6 m) and peat carbon density (mean 1,712 ± 634 MgC ha−1; maximum 3,970 MgC ha−1) for the central Congo Basin. We show that the peatland complex covers 167,600 km2, 36% of the world’s tropical peatland area, and that 29.0 PgC is stored below ground in peat across the region (95% confidence interval, 26.3–32.2 PgC). Our measurement-based constraints give high confidence of globally significant peat carbon stocks in the central Congo Basin, totalling approximately 28% of the world’s tropical peat carbon. Only 8% of this peat carbon lies within nationally protected areas, suggesting its vulnerability to future land-use change.
  • Thumbnail Image
    ItemOpen Access
    Mapping water levels across a region of the Cuvette Centrale peatland complex
    (MDPI, 2023-06-13) Georgiou, Selena; Mitchard, Edward T. A.; Crezee, Bart; Dargie, Greta C.; Young, Dylan M.; Jovani-Sancho, Antonio J.; Kitambo, Benjamin; Papa, Fabrice; Bocko, Yannick E.; Bola, Pierre; Crabtree, Dafydd E.; Emba, Ovide B.; Ewango, Corneille E. N.; Girkin, Nicholas T.; Ifo, Suspense A.; Kanyama, Joseph T.; Mampouya, Yeto Emmanuel Wenina; Mbemba, Mackline; Ndjango, Jean-Bosco N.; Palmer, Paul I.; Sjögersten, Sofie; Lewis, Simon L.
    Inundation dynamics are the primary control on greenhouse gas emissions from peatlands. Situated in the central Congo Basin, the Cuvette Centrale is the largest tropical peatland complex. However, our knowledge of the spatial and temporal variations in its water levels is limited. By addressing this gap, we can quantify the relationship between the Cuvette Centrale’s water levels and greenhouse gas emissions, and further provide a baseline from which deviations caused by climate or land-use change can be observed, and their impacts understood. We present here a novel approach that combines satellite-derived rainfall, evapotranspiration and L-band Synthetic Aperture Radar (SAR) data to estimate spatial and temporal changes in water level across a sub-region of the Cuvette Centrale. Our key outputs are a map showing the spatial distribution of rainfed and flood-prone locations and a daily, 100 m resolution map of peatland water levels. This map is validated using satellite altimetry data and in situ water table data from water loggers. We determine that 50% of peatlands within our study area are largely rainfed, and a further 22.5% are somewhat rainfed, receiving hydrological input mostly from rainfall (directly and via surface/sub-surface inputs in sloped areas). The remaining 27.5% of peatlands are mainly situated in riverine floodplain areas to the east of the Congo River and between the Ubangui and Congo rivers. The mean amplitude of the water level across our study area and over a 20-month period is 22.8 ± 10.1 cm to 1 standard deviation. Maximum temporal variations in water levels occur in the riverine floodplain areas and in the inter-fluvial region between the Ubangui and Congo rivers. Our results show that spatial and temporal changes in water levels can be successfully mapped over tropical peatlands using the pattern of net water input (rainfall minus evapotranspiration, not accounting for run-off) and L-band SAR data.
  • Thumbnail Image
    ItemOpen Access
    Opportunities for enhancing the climate resilience of coffee production through improved crop, soil and water management
    (Taylor and Francis, 2023-06-27) Bracken, Phoebe; Burgess, Paul J.; Girkin, Nicholas T.
    Climate change is adversely affecting coffee production, impacting both yields and quality. Coffee production is dominated by the cultivation of Arabica and Robusta coffee, species that represent 99% of production, but both will be affected by climate change. Sustainable management practices that can enhance the resilience of production and livelihoods to climate change are urgently needed as production supports the livelihoods of over 25 million people globally, the majority of whom are smallholder farmers located in the coffee belt spanning the tropics. These communities are already experiencing the impacts of climate change. We conducted a systematic review, identifying 80 studies that describe the direct and indirect impacts of climate change on coffee agroecosystems, or that identify agroecological practices with the potential to enhance climate resilience. Adverse environmental impacts include a reduction in area suitable for production, lower yields, increased intensity and frequency of extreme climate events, and greater incidence of pests and diseases. Potential environmental solutions include altitudinal shifts, new, resilient cultivars, altering agrochemical inputs, and agroforestry. However, financial, environmental and technical constraints limit the availability of many of these approaches to farmers, particularly smallholder producers. There is therefore an urgent need to address these barriers through policy and market mechanisms, and stakeholder engagement to continue meeting the growing demand for coffee.
  • Thumbnail Image
    ItemOpen Access
    Organic management in coffee: a systematic review of the environmental, economic and social benefits and trade-offs for farmers
    (Taylor and Francis, 2025-05-29) Jones, Katharine; Njeru, Ezekiel Mugendi; Garnett, Kenisha; Girkin, Nicholas T.
    Global coffee production is expanding, contributing to environmental degradation, notably through extensive use of inorganic fertilizers. Volatile prices, climate change, rising input costs, and pressure to decrease carbon footprints represent key challenges for farmers. Regenerative soil management and the use of organic management as an alternative to conventional mineral fertilizers offer one potential solution to address these challenges. However, information is limited regarding the potential options available for farmers, and their potential environmental, economic, and social impacts. We undertook a systematic review of the literature to assess the benefits and trade-offs from adopting different organic management approaches following PRISMA guidelines. We identified 43 peer-reviewed articles, predominantly focusing on agroforestry, plant-derived additions, soil management or animal manure to improve livelihoods and environment. Research priorities differ by region and there is a skew toward researching the environmental impacts of regenerative techniques. Our synthesis demonstrates multiple potential environmental benefits to organic management, but increasing economic risks and trade-offs for farmers, particularly in transitioning to organic management. We also highlight the social barriers facing farmers, from education to access to knowledge networks to support implementation. These challenges must be addressed to support any future sustainable transitions to organic management in coffee.
  • Thumbnail Image
    ItemOpen Access
    Root oxygen mitigates methane fluxes in tropical peatlands
    (IOP, 2020-05-27) Girkin, Nicholas T.; Vane, Christopher H.; Turner, Benjamin L.; Ostle, Nicholas J.; Sjögersten, Sofie
    Tropical peatlands are a globally important source of methane, a potent greenhouse gas. Vegetation is critical in regulating fluxes, providing a conduit for emissions and regular carbon inputs. However, plant roots also release oxygen, which might mitigate methane efflux through oxidation prior to emission from the peat surface. Here we show, using in situ mesocosms, that root exclusion can reduce methane fluxes by a maximum of 92% depending on species, likely driven by the significant decrease in root inputs of oxygen and changes in the balance of methane transport pathways. Methanotroph abundance decreased with reduced oxygen input, demonstrating a likely mechanism for the observed response. These first methane oxidation estimates for a tropical peatland demonstrate that although plants provide an important pathway for methane loss, this can be balanced by the influence of root oxygen inputs that mitigate peat surface methane emissions.
  • No Thumbnail Available
    ItemOpen Access
    Root oxygen mitigates methane fluxes in tropical peatlands: data
    (Cranfield University, 2021-06-21 13:47) Girkin, Nicholas T.; Vane, Christopher H.; Turner, Benjamin L.; Ostle, Nicholas J.; Sjagersten, Sofie
    Tropical peatlands are a globally important source of methane, a potent greenhouse gas. Vegetation is critical in regulating fluxes, providing a conduit for emissions and regular carbon inputs. However, plant roots also release oxygen, which might mitigate methane efflux through oxidation prior to emission from the peat surface. Here we show, using in situ mesocosms, that root exclusion can reduce methane fluxes by a maximum of 92% depending on species, likely driven by the significant decrease in root inputs of oxygen and changes in the balance of methane transport pathways. Methanotroph abundance decreased with reduced oxygen input, demonstrating a likely mechanism for the observed response. These first methane oxidation estimates for a tropical peatland demonstrate that although plants provide an important pathway for methane loss, this can be balanced by the influence of root oxygen inputs that mitigate peat surface methane emissions. This data includes measurements of methane fluxes, peat organic matter properties as assessed by Rock-Eval pyrolysis, bulk peat properties, and microbial community structure as assessed by phospholipid fatty acid (PLFA) analysis.
  • Thumbnail Image
    ItemOpen Access
    Simulating carbon accumulation and loss in the central Congo peatlands
    (Wiley, 2023-10-10) Young, Dylan M.; Baird, Andy J.; Morris, Paul J.; Dargie, Greta C.; Mampouya Wenina, Y. Emmanuel; Mbemba, Mackline; Boom, Arnoud; Cook, Peter; Betts, Richard; Burke, Eleanor; Bocko, Yannick E.; Chadburn, Sarah; Crabtree, Dafydd E.; Crezee, Bart; Ewango, Corneille E. N.; Garcin, Yannick; Georgiou, Selena; Girkin, Nicholas T.; Gulliver, Pauline; Jovani-Sancho, A. Jonay; Schefuß, Enno; Sciumbata, Matteo; Sjögersten, Sofie; Lewis, Simon L.
    Peatlands of the central Congo Basin have accumulated carbon over millennia. They currently store some 29 billion tonnes of carbon in peat. However, our understanding of the controls on peat carbon accumulation and loss and the vulnerability of this stored carbon to climate change is in its infancy. Here we present a new model of tropical peatland development, DigiBog_Congo, that we use to simulate peat carbon accumulation and loss in a rain-fed interfluvial peatland that began forming ~20,000 calendar years Before Present (cal. yr BP, where ‘present’ is 1950 CE). Overall, the simulated age-depth curve is in good agreement with palaeoenvironmental reconstructions derived from a peat core at the same location as our model simulation. We find two key controls on long-term peat accumulation: water at the peat surface (surface wetness) and the very slow anoxic decay of recalcitrant material. Our main simulation shows that between the Late Glacial and early Holocene there were several multidecadal periods where net peat and carbon gain alternated with net loss. Later, a climatic dry phase beginning ~5200 cal. yr BP caused the peatland to become a long-term carbon source from ~3975 to 900 cal. yr BP. Peat as old as ~7000 cal. yr BP was decomposed before the peatland's surface became wetter again, suggesting that changes in rainfall alone were sufficient to cause a catastrophic loss of peat carbon lasting thousands of years. During this time, 6.4 m of the column of peat was lost, resulting in 57% of the simulated carbon stock being released. Our study provides an approach to understanding the future impact of climate change and potential land-use change on this vulnerable store of carbon.
  • Thumbnail Image
    ItemOpen Access
    Spatial variability of surface peat properties and carbon emissions in a tropical peatland oil palm monoculture during a dry season
    (Wiley, 2021-06-22) Dhandapani, Selva; Girkin, Nicholas T.; Evers, Stephanie
    The expansion of oil palm monocultures into globally important Southeast Asian tropical peatlands has caused severe environmental damage. Despite much of the current focus of environmental impacts being directed at industrial scale plantations, over half of oil palm land-use cover in Southeast Asia is from smallholder plantations. We differentiated a first generation smallholder oil palm monoculture into 8 different sampling zones, and further divided the 8 sampling zones into oil palm root influenced (Proximal) and reduced root influence (Distal) areas, to assess how peat properties regulate in situ carbon dioxide (CO2) and methane (CH4) fluxes. We found that all the physico-chemical properties and nutrient concentrations except sulphur varied significantly among heterogeneous zones. All physico-chemical properties except electrical conductivity, and all nutrient content except nitrogen and potassium varied significantly between Proximal and Distal areas. Mean CO2 fluxes (ranged between 382 and 1191 mg m-2 hr-1) varied significantly among heterogeneous zones, and between Proximal and Distal areas, with notably high emissions in Dead Wood and Path zones, and consistently higher emissions in Proximal areas compared Distal areas within almost all the zones. CH4 fluxes (ranged between -32 and 243 µg m-2 hr-1) did not significantly vary between Proximal and Distal areas, however significantly varied amongst heterogenous zones. CH4 flux were notably high in Canal Edge and Understorey Ferns zones, and negative in Dead Wood zone. The results demonstrate the high heterogeneity of peat properties within oil palm monoculture, strengthening the need for intensive sampling to characterise a land-use in the tropical peatlands.