Johnstown Castle is Ireland’s leading research centre for soils and the rural environment. The centre conducts research on soils; nutrient efficiency; recovery and losses; air and water quality; the agricultural environment and agro-ecology. The research results generated are used widely by advisors, farmers, scientists and policy makers.

Recent Submissions

  • Higher species richness enhances yield stability in intensively managed grasslands with experimental disturbance

    Haughey, Eamon; Suter, Matthias; Hofer, Daniel; Hoekstra, Nyncke J.; McElwain, Jennifer C.; Lüscher, Andreas; Finn, John A. (Springer Science and Business Media LLC, 2018-10-09)
    Climate models predict increased frequency and severity of drought events. At an Irish and Swiss site, experimental summer droughts were applied over two successive years to grassland plots sown with one, two or four grassland species with contrasting functional traits. Mean yield and plot-to-plot variance of yield were measured across harvests during drought and after a subsequent post-drought recovery period. At both sites, there was a positive relationship between species richness and yield. Under rainfed control conditions, mean yields of four-species communities were 32% (Wexford, Ireland) and 51% (Zürich, Switzerland) higher than in monocultures. This positive relationship was also evident under drought, despite signifcant average yield reductions (−27% at Wexford; −21% at Zürich). Fourspecies communities had lower plot-to-plot variance of yield compared to monoculture or two-species communities under both rainfed and drought conditions, which demonstrates higher yield stability in four-species communities. At the Swiss but not the Irish site, a high degree of species asynchrony could be identifed as a mechanism underlying increased temporal stability in four-species communities. These results indicate the high potential of multi-species grasslands as an adaptation strategy against drought events and help achieve sustainable intensifcation under both unperturbed and perturbed environmental conditions.
  • Assessment of Benefits of Conservation Agriculture on Soil Functions in Arable Production Systems in Europe

    Ghaley, Bhim; Rusu, Teodor; Sandén, Taru; Spiegel, Heide; Menta, Cristina; Visioli, Giovanna; O’Sullivan, Lilian; Gattin, Isabelle; Delgado, Antonio; Liebig, Mark; et al. (Multidisciplinary Digital Publishing Institute, 2018-03-13)
    Conventional farming (CONV) is the norm in European farming, causing adverse effects on some of the five major soil functions, viz. primary productivity, carbon sequestration and regulation, nutrient cycling and provision, water regulation and purification, and habitat for functional and intrinsic biodiversity. Conservation agriculture (CA) is an alternative to enhance soil functions. However, there is no analysis of CA benefits on the five soil functions as most studies addressed individual soil functions. The objective was to compare effects of CA and CONV practices on the five soil functions in four major environmental zones (Atlantic North, Pannonian, Continental and Mediterranean North) in Europe by applying expert scoring based on synthesis of existing literature. In each environmental zone, a team of experts scored the five soil functions due to CA and CONV treatments and median scores indicated the overall effects on five soil functions. Across the environmental zones, CONV had overall negative effects on soil functions with a median score of 0.50 whereas CA had overall positive effects with median score ranging from 0.80 to 0.83. The study proposes the need for field-based investigations, policies and subsidy support to benefit from CA adoption to enhance the five soil functions.
  • Weed suppression greatly increased by plant diversity in intensively managed grasslands: A continental-scale experiment

    Connolly, John; Sebastià, Maria-Teresa; Kirwan, Laura; Finn, John Anthony; Llurba, Rosa; Suter, Matthias; Collins, Rosemary P.; Porqueddu, Claudio; Helgadóttir, Áslaug; Baadshaug, Ole H.; et al. (Wiley, 2017-09-27)
    Grassland diversity can support sustainable intensification of grassland production through increased yields, reduced inputs and limited weed invasion. We report the effects of diversity on weed suppression from 3 years of a 31-site continental-scale field experiment.At each site, 15 grassland communities comprising four monocultures and 11 four-species mixtures based on a wide range of species' proportions were sown at two densities and managed by cutting. Forage species were selected according to two crossed functional traits, "method of nitrogen acquisition" and "pattern of temporal development".Across sites, years and sown densities, annual weed biomass in mixtures and monocultures was 0.5 and 2.0 t DM ha-1 (7% and 33% of total biomass respectively). Over 95% of mixtures had weed biomass lower than the average of monocultures, and in two-thirds of cases, lower than in the most suppressive monoculture (transgressive suppression). Suppression was significantly transgressive for 58% of site-years. Transgressive suppression by mixtures was maintained across years, independent of site productivity.Based on models, average weed biomass in mixture over the whole experiment was 52% less (95% confidence interval: 30%-75%) than in the most suppressive monoculture. Transgressive suppression of weed biomass was significant at each year across all mixtures and for each mixture.Weed biomass was consistently low across all mixtures and years and was in some cases significantly but not largely different from that in the equiproportional mixture. The average variability (standard deviation) of annual weed biomass within a site was much lower for mixtures (0.42) than for monocultures (1.77). Synthesis and applications. Weed invasion can be diminished through a combination of forage species selected for complementarity and persistence traits in systems designed to reduce reliance on fertiliser nitrogen. In this study, effects of diversity on weed suppression were consistently strong across mixtures varying widely in species' proportions and over time. The level of weed biomass did not vary greatly across mixtures varying widely in proportions of sown species. These diversity benefits in intensively managed grasslands are relevant for the sustainable intensification of agriculture and, importantly, are achievable through practical farm-scale actions.
  • Distinct responses of soil respiration to experimental litter manipulation in temperate woodland and tropical forest

    Bréchet, Laëtitia M.; Lopez-Sangil, Luis; George, Charles; Birkett, Ali J.; Baxendale, Catherine; Castro Trujillo, Biancolini; Sayer, Emma J.; European Research Council; ERC/307888 (Wiley, 2018-03-13)
    Global change is affecting primary productivity in forests worldwide, and this, in turn, will alter long-term carbon (C) sequestration in wooded ecosystems. On one hand, increased primary productivity, for example, in response to elevated atmospheric carbon dioxide (CO2), can result in greater inputs of organic matter to the soil, which could increase C sequestration belowground. On other hand, many of the interactions between plants and microorganisms that determine soil C dynamics are poorly characterized, and additional inputs of plant material, such as leaf litter, can result in the mineralization of soil organic matter, and the release of soil C as CO2 during so-called “priming effects”. Until now, very few studies made direct comparison of changes in soil C dynamics in response to altered plant inputs in different wooded ecosystems. We addressed this with a cross-continental study with litter removal and addition treatments in a temperate woodland (Wytham Woods) and lowland tropical forest (Gigante forest) to compare the consequences of increased litterfall on soil respiration in two distinct wooded ecosystems. Mean soil respiration was almost twice as high at Gigante (5.0 μmol CO2 m−2 s−1) than at Wytham (2.7 μmol CO2 m−2 s−1) but surprisingly, litter manipulation treatments had a greater and more immediate effect on soil respiration at Wytham. We measured a 30% increase in soil respiration in response to litter addition treatments at Wytham, compared to a 10% increase at Gigante. Importantly, despite higher soil respiration rates at Gigante, priming effects were stronger and more consistent at Wytham. Our results suggest that in situ priming effects in wooded ecosystems track seasonality in litterfall and soil respiration but the amount of soil C released by priming is not proportional to rates of soil respiration. Instead, priming effects may be promoted by larger inputs of organic matter combined with slower turnover rates.
  • A novel hybrid coagulation-constructed wetland system for the treatment of dairy wastewater

    Mohamed, A.Y.A.; Siggins, A.; Healy, M.G.; Ó hUallacháin, Daire; Fenton, Owen; Tuohy, P.; Teagasc Walsh Fellowship; RMIS-0386 (Elsevier, 2022-07-29)
    Constructed wetlands (CWs) are a cost-effective and sustainable treatment technology that may be used on farms to treat dairy wastewater (DWW). However, CWs require a large area for optimal treatment and have poor long-term phosphorus removal. To overcome these limitations, this study uses a novel, pilot-scale coagulation-sedimentation process prior to loading CWs with DWW. This hybrid system, which was operated on an Irish farm over an entire milking season, performed well at higher hydraulic loading rates than conventional CWs, and obtained removal efficiencies ≥99 % for all measured water quality parameters (chemical oxygen demand, total nitrogen and phosphorus, total suspended solids and turbidity), which complied with EU directives concerning urban wastewater treatment. Overall, the hybrid coagulation-CW is a promising technology that requires a smaller area than conventional CWs and minimal operator input, and produces high effluent quality.
  • Grassland legacy effects on yield of a follow-on crop in rotation strongly influenced by legume proportion and moderately by drought

    Grange, Guylain; Brophy, Caroline; Finn, John; Science Foundation Ireland; Teagasc Walsh Scholarship; 19/FFP/6888 (Elsevier, 2022-08-31)
    We investigated the degree to which plant species diversity, drought and fertiliser level in a grassland ley can affect performance of a follow-on crop in a rotation. Grassland species and functional group diversity (grasses, legumes and herbs) were manipulated from monocultures to six-species mixtures in the grassland ley phase. A simulated two-month summer drought treatment was compared to a ‘rainfed’ control. Plots received 150 kg ha−1 yr−1 of nitrogen (N) fertiliser; additional replicates of L. perenne monoculture received 300 kg ha−1 yr−1 of N fertiliser. After two years, grassland communities were terminated, and each plot reseeded with an Italian ryegrass (Lolium multiflorum) model crop; its yield indicated the relative legacy effect of the preceding treatments (plant diversity, drought, N input). There was a modest but constant negative effect of drought on dry matter (−0.36 ± 0.091 t ha−1) and nitrogen yield (DMY and NY respectively) of the subsequent crop of L. multiflorum, across all plant communities. There were strong differences among the identity effects of the six former grassland species on DMY and NY of L. multiflorum. Legume species had the strongest effects on DMY of L. multiflorum (6.09 t ha−1 for the former T. pratense monoculture and 6.54 t ha−1 for T. repens). The lowest crop yield was from the former low-diversity high-input replicates (4.16 t ha−1 for former L. perenne monoculture with 300 kg ha−1 yr−1). There was no evidence that interspecific interactions in the grassland phase affected yield of the follow-on crop. Thus, the legacy effect of grassland mixtures was estimated by the identities and proportions of the species sown in the mixture. Similar patterns were obtained for NY. High-diversity, low-input grassland yielded more DMY and NY than low-diversity, high-input grassland (across both ley and follow-on crop phases). However, a legume proportion in the grassland ley of at least 33% is required to achieve high forage and crop performance in a grassland-crop rotation.
  • Biomass and nutrient dynamics of major green tides in Ireland: Implications for biomonitoring

    Bermejo, Ricardo; Golden, Nessa; Schrofner, Elena; Knöller, Kay; Fenton, Owen; Serrão, Ester; Morrison, Liam; Environmental Protection Agency, Ireland; Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia; 2014-2020 ERDF Operational Programme; et al. (Elsevier, 2022-02-28)
    The control of macroalgal bloom development is central for protecting estuarine ecosystems. The identification of the nutrients limiting the development of macroalgal blooms, and their most likely sources is crucial for management strategies. Three Irish estuaries (Argideen, Clonakilty and Tolka) affected by green tides were monitored from June 2016 to August 2017. During each sampling occasion, biomass abundances, tissue N and P contents, and δ15N were determined for tubular and laminar morphologies of Ulva. All estuaries showed maximum biomass during summer and minimum during winter. Tissue nutrient contents revealed P rather than N limitation. The δ15N during the peak bloom indicated agriculture as the most likely source of nitrogen in the Argideen and Clonakilty, and urban wastewaters in the Tolka. No differences in the δ15N, and the tissue nutrients content were observed between morphologies. The period between May and July is most suitable for bioassessment of green tides.
  • Using a multi-dimensional approach for catchment scale herbicide pollution assessments.

    Khan, Majid Ali; Costa, Fabiola Barros; Fenton, Owen; Jordan, Phil; Fennell, Chris; Mellander, Per-Erik; European Union; 727450 (Elsevier, 2020-07-25)
    Worldwide herbicide use in agriculture, whilst safeguarding yields also presents water quality issues. Controlling factors in agricultural catchments include both static and dynamic parameters. The present study investigated the occurrence of herbicides in streams and groundwater in two meso-scale catchments with contrasting flow controls and agricultural landuse (grassland and arable land). Using a multi-dimensional approach, streams were monitored from November 2018 to November 2019 using Chemcatcher® passive sampling devices and groundwater was sampled in 95 private drinking water wells. The concentrations of herbicides were larger in the stream of the Grassland catchment (8.9-472.6 ng L-1) dominated by poorly drained soils than in the Arable catchment (0.9-169.1 ng L-1) dominated by well-drained soils. Incidental losses of herbicides during time of application and low flows in summer caused concentrations of MCPA, Fluroxypyr, Trichlorpyr, Clopyralid and Mecoprop to exceeded the European Union (EU) drinking water standard due to a lack of dilution. Herbicides were present in the stream throughout the year and the total mass load was higher in winter flows, suggesting a persistence of primary chemical residues in soil and sub-surface environments and restricted degradation. Losses of herbicides to the streams were source limited and influenced by hydrological conditions. Herbicides were detected in 38% of surveyed drinking water wells. While most areas had concentrations below the EU drinking water standard some areas with well-drained soils in the Grassland catchment, had concentrations exceeding recommendations. Individual wells had concentrations of Clopyralid (619 ng L-1) and Trichlorpyr (650 ng L-1). Despite the study areas not usually associated with herbicide pollution, and annual mass loads being comparatively low, many herbicides were present in both surface and groundwater, sometimes above the recommendations for drinking water. This whole catchment assessment provides a basis to develop collaborative measures to mitigate pollution of water by herbicides.
  • An investigation of anticoccidial veterinary drugs as emerging organic contaminants in groundwater

    Mooney, D.; Richards, K.G.; Danaher, M.; Grant, J.; Gill, L.; Mellander, P.-E.; Coxon, C.E.; Science Foundation Ireland; European Regional Development Fund; Teagasc Walsh Scholarship Programme; et al. (Elsevier BV, 2020-12)
    Intensification of the food production system to meet increased global demand for food has led to veterinary pharmaceuticals becoming a critical component in animal husbandry. Anticoccidials are a group of veterinary products used to control coccidiosis in food-producing animals, with primary prophylactic use in poultry production. Excretion in manure and subsequent land-spreading provides a potential pathway to groundwater. Information on the fate and occurrence of these compounds in groundwater is scant, therefore these substances are potential emerging organic contaminants of concern. A study was carried out to investigate the occurrence of anticoccidial compounds in groundwater throughout the Republic of Ireland. Twenty-six anticoccidials (6 ionophores and 20 synthetic anticoccidials) were analysed at 109 sites (63 boreholes and 46 springs) during November and December 2018. Sites were categorised and selected based on the following source and pathway factors: (a) the presence/absence of poultry activity (b) predominant aquifer category and (c) predominant groundwater vulnerability, within the zone of contribution (ZOC) for each site. Seven anticoccidials, including four ionophores (lasalocid, monensin, narasin and salinomycin) and three synthetic anticoccidials (amprolium, diclazuril and nicarbazin), were detected at 24% of sites at concentrations ranging from 1 to 386 ng L−1. Monensin and amprolium were the two most frequently detected compounds, detected at 15% and 7% of sites, respectively. Multivariate statistical analysis has shown that source factors are the most significant drivers of the occurrence of anticoccidials, with no definitive relationships between occurrence and pathway factors. The study found that the detection of anticoccidial compounds is 6.5 times more likely when poultry activity is present within the ZOC of a sampling point, compared to the absence of poultry activity. This work presents the first detections of these contaminants in Irish groundwater and it contributes to broadening our understanding of the environmental occurrence and fate of anticoccidial veterinary products.
  • The distribution, type, popularity, size and availability of river-run gravel and crushed stone for use in land drainage systems and their suitability for mineral soils in Ireland

    Byrne, I.; Healy, M. G.; Fenton, Owen; Tuohy, P. (Teagasc, 2022-06-24)
    The performance of land drainage systems installed in mineral soils in Ireland is highly variable, and is dependent on, amongst other factors, the quality and suitability of the aggregate used. In Ireland, aggregate for land drainage systems is usually river-run gravel and crushed stone. This study classified the distribution, type, popularity, size and availability of aggregates for land drainage systems throughout Ireland and quantified their suitability for use in mineral soils. Eighty-six quarries were surveyed. Limestone and river-run gravel (80% of lithologies) are widespread throughout the country. The quarry aggregate sizes (“Q sizes”), reported by the quarries as either a single size, that is, “50 mm”, or a graded size, that is, 20–40 mm, were variable, changed across lithology and region and were, in most cases, larger than what is currently recommended. A particle size distribution analysis of 74 samples from 62 quarries showed that individual Q sizes increased in variability with increasing aggregate size. In some regions, the aggregate sold does not meet current national regulations, which specify an aggregate size ranging from 10 to 40 mm. The suitability of these aggregates for drainage in five soils of different textures was compared using three established design criteria. It was found that the aggregate in use is too large for heavy soil textures and is therefore unsuitable as drainage envelope material. Guidance for contractors, farmers and quarry owners will be required, and investment may be needed by quarries to produce aggregate that satisfies design criteria. An aggregate size, based on one or a combination of established aggregate design criteria, where an analysis of the soil texture is conducted and an appropriate aggregate is chosen based off its 15% passing size, is required.
  • Datafile: Grassland legacy effects on yield of a follow-on crop in rotation strongly influenced by legume proportion and moderately by drought

    Grange, Guylain; Brophy, Caroline; Finn, John (2022)
    Dataset contains the dry matter and nitrogen yield responses of a Lolium multiflorum crop (summed across harvests). The L. multiflorum crop was sown on plots comprising grassland communities of one to six species (and one to three functional groups) that were growing for the previous two years. An experimental summer drought was implemented on half of each plot during the grassland phase but not the crop phase. Data were collected in Wexford, Republic of Ireland (52.299584, -6.506458) in 2020.
  • Data file: A landscape classification map of Ireland and its potential use in national land use monitoring.

    Carlier, J.; Doyle, M.; Finn, John; Ó hUallacháin, D.; Moran, J.; Department of Agriculture, Food and the Marine; 2019R425 (Elsevier, 2021)
    This data file provides the map (png file) and GIS data associated with a publication in the Journal of Environmental Management titled 'A landscape classification map of Ireland and its potential use in national land use monitoring.'
  • A landscape classification map of Ireland and its potential use in national land use monitoring

    Carlier, J.; Doyle, M.; Finn, John; O hUallachain, Daire; Moran, J.; Department of Agriculture, Food and the Marine; 2019R425 (Elsevier BV, 2021-07)
    This study presents a novel landscape classification map of the Republic of Ireland and is the first to identify broad landscape classes by incorporating physiographic and land cover data. The landscape classification responds to commitments to identify and classify the Irish landscape as a signatory to the European Landscape Convention. The methodology applied a series of clustering iterations to determine an objective multivariate classification of physiographic landscape units and land cover datasets. The classification results determined nine statistically significant landscape classes and the development of a landscape classification map at a national scale. A statistical breakdown of land cover area and diversity of each class was interpreted, and a comparison was extended using independent descriptive variables including farmland use intensity, elevation, and dominant soil type. Each class depicts unique spatial and composition characteristics, from coastal, lowland and elevated, to distinct and dominating land cover types, further explained by the descriptive variables. The significance of individual classes and success of the classification is discussed with particular reference to the wider applicability of the map. The transferability of the methodology to other existing physiographic maps and environmental datasets to generate new landscape classifications is also considered. This novel work facilitates the development of a strategic framework to efficiently monitor, compare and analyse ecological and other land use data that is spatially representative of the distribution and extent of land cover in the Irish countryside.
  • Benchmarking a decade of holistic agro-environmental studies within the Agricultural Catchments Programme

    Mellander, Per-Erik; Lynch, M.B.; Galloway, J.; Žurovec, O.; McCormack, Michele; O’Neill, M.; Hawtree, D.; Burgess, E.; Department of Agriculture, Food and the Marine (Teagasc, 2022-02-26)
    Meeting sustainable food production challenges requires efficient ways to manage nutrients and mitigate the losses of nitrogen (N) and phosphorus (P) to water. Future nutrient management therefore requires a clearer understanding of the relative influence of soils, geology, farm practice, landscape and weather on the propensity for nutrients to be lost to water. Within the Agricultural Catchments Programme (ACP), environmental, agronomic and socioeconomic data have been gathered since 2009, using the same experimental methodology in five meso-scale river catchments, and one karst spring zone, covering a range of soils, landscapes and farming systems. The ACP has contributed to a better understanding of nutrient mobilisation and transfer pathways and highlighted the influence of the physical and chemical environment as well as agricultural and meteorological drivers on diffuse nutrient loss to ground and surface waters. The environmental quality standards were breached for N and/or P in some of the catchments, but for different reasons and not always clearly linked to the source pressures within the catchment. There are clearly no one-size-fits-all solutions for mitigation of nutrient losses to water. A better understanding of the underlying processes is required to identify critical source areas, to select mitigation strategies, when to implement them and to build realistic expectations of their impact. Sustainability in an agricultural setting is not confined to environmental issues, but also includes social, economic and innovative aspects. To maximise farmers’ uptake of environmental measures, the actions should encompass all these aspects of sustainability. Integrated knowledge transfer is key.
  • Scenarios to limit environmental nitrogen losses from dairy expansion

    Hoekstra, N.J.; Schulte, R.P.O.; Forrestal, P.J.; Hennessy, Deirdre; Krol, Dominika; Lanigan, Gary J.; Müller, C.; Shalloo, Laurence; Wall, David P.; Richards, Karl G.; et al. (Elsevier, 2020-03-10)
    Increased global demand for dairy produce and the abolition of EU milk quotas have resulted in expansion in dairy production across Europe and particularly in Ireland. Simultaneously, there is increasing pressure to reduce the impact of nitrogen (N) losses to air and groundwater on the environment. In order to develop grassland management strategies for grazing systems that meet environmental targets and are economically sustainable, it is imperative that individual mitigation measures for N efficiency are assessed at farm system level. To this end, we developed an excel-based N flow model simulating an Irish grass-based dairy farm, to evaluate the effect of farm management on N efficiency, N losses, production and economic performance. The model was applied to assess the effect of different strategies to achieve the increased production goals on N utilization, N loss pathways and economic performance at farm level. The three strategies investigated included increased milk production through increased grass production, through increased concentrate feeding and by applying a high profit grass-based system. Additionally, three mitigation measures; low ammonia emission slurry application, the use of urease and nitrification inhibitors and the combination of both were applied to the three strategies. Absolute N emissions were higher for all intensification scenarios (up to 124 kg N ha−1) compared to the baseline (80 kg N ha−1) due to increased animal numbers and higher feed and/or fertiliser inputs. However, some intensification strategies showed the potential to reduce the emissions per ton milk produced for some of the N-loss pathways. The model showed that the assessed mitigation measures can play an important role in ameliorating the increased emissions associated with intensification, but may not be adequate to entirely offset absolute increases. Further improvements in farm N use efficiency and alternatives to mineral fertilisers will be required to decouple production from reactive N emissions.
  • Development of a defined compost system for the study of plant-microbe interactions

    Masters-Clark, E.; Shone, E.; Paradelo, M.; Hirsch, P. R.; Clark, I. M.; Otten, W.; Brennan, Fiona; Mauchline, T. H.; Teagasc Walsh Fellowship Programme; Natural Environment Research Council; et al. (Springer Science and Business Media LLC, 2020-05-05)
    Plant growth promoting rhizobacteria can improve plant health by providing enhanced nutrition, disease suppression and abiotic stress resistance, and have potential to contribute to sustainable agriculture. We have developed a sphagnum peat-based compost platform for investigating plantmicrobe interactions. The chemical, physical and biological status of the system can be manipulated to understand the relative importance of these factors for plant health, demonstrated using three case studies: 1. Nutrient depleted compost retained its structure, but plants grown in this medium were severely stunted in growth due to removal of essential soluble nutrients - particularly, nitrogen, phosphorus and potassium. Compost nutrient status was replenished with the addition of selected soluble nutrients, validated by plant biomass; 2. When comparing milled and unmilled compost, we found nutrient status to be more important than matrix structure for plant growth; 3. In compost defcient in soluble P, supplemented with an insoluble inorganic form of P (Ca3(PO4)2), application of a phosphate solubilising Pseudomonas strain to plant roots provides a signifcant growth boost when compared with a Pseudomonas strain incapable of solubilising Ca3(PO4)2. Our fndings show that the compost system can be manipulated to impose biotic and abiotic stresses for testing how microbial inoculants infuence plant growth.
  • Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs

    Sayer, Emma J.; Lopez-Sangil, Luis; Crawford, John A.; Bréchet, Laëtitia M.; Birkett, Ali J.; Baxendale, Catherine; Castro, Biancolini; Rodtassana, Chadtip; Garnett, Mark H.; Weiss, Lena; et al. (Springer Science and Business Media LLC, 2020-07-23)
    Soil organic carbon (SOC) dynamics represent a persisting uncertainty in our understanding of the global carbon cycle. SOC storage is strongly linked to plant inputs via the formation of soil organic matter, but soil geochemistry also plays a critical role. In tropical soils with rapid SOC turnover, the association of organic matter with soil minerals is particularly important for stabilising SOC but projected increases in tropical forest productivity could trigger feedbacks that stimulate the release of stored SOC. Here, we demonstrate limited additional SOC storage after 13–15 years of experimentally doubled aboveground litter inputs in a lowland tropical forest. We combined biological, physical, and chemical methods to characterise SOC along a gradient of bioavailability. After 13 years of monthly litter addition treatments, most of the additional SOC was readily bioavailable and we observed no increase in mineral-associated SOC. Importantly, SOC with weak association to soil minerals declined in response to long-term litter addition, suggesting that increased plant inputs could modify the formation of organo-mineral complexes in tropical soils. Hence, we demonstrate the limited capacity of tropical soils to sequester additional C inputs and provide insights into potential underlying mechanisms.
  • Impact of nitrogen compounds on fungal and bacterial contributions to codenitrification in a pasture soil

    Rex, David; Clough, Timothy J.; Richards, Karl G.; Condron, Leo M.; de Klein, Cecile A. M.; Morales, Sergio E.; Lanigan, Gary J.; New Zealand Government; Teagasc Walsh Fellowship Programme; 16084 (Springer Science and Business Media LLC, 2019-09-16)
    Ruminant urine patches on grazed grassland are a signifcant source of agricultural nitrous oxide (N2O) emissions. Of the many biotic and abiotic N2O production mechanisms initiated following urine-urea deposition, codenitrifcation resulting in the formation of hybrid N2O, is one of the least understood. Codenitrifcation forms hybrid N2O via biotic N-nitrosation, co-metabolising organic and inorganic N compounds (N substrates) to produce N2O. The objective of this study was to assess the relative signifcance of diferent N substrates on codenitrifcation and to determine the contributions of fungi and bacteria to codenitrifcation. 15N-labelled ammonium, hydroxylamine (NH2OH) and two amino acids (phenylalanine or glycine) were applied, separately, to sieved soil mesocosms eight days after a simulated urine event, in the absence or presence of bacterial and fungal inhibitors. Soil chemical variables and N2O fuxes were monitored and the codenitrifed N2O fuxes determined. Fungal inhibition decreased N2O fuxes by ca. 40% for both amino acid treatments, while bacterial inhibition only decreased the N2O fux of the glycine treatment, by 14%. Hydroxylamine (NH2OH) generated the highest N2O fuxes which declined with either fungal or bacterial inhibition alone, while combined inhibition resulted in a 60% decrease in the N2O fux. All the N substrates examined participated to some extent in codenitrifcation. Trends for codenitrifcation under the NH2OH substrate treatment followed those of total N2O fuxes (85.7% of total N2O fux). Codenitrifcation fuxes under non-NH2OH substrate treatments (0.7–1.2% of total N2O fux) were two orders of magnitude lower, and signifcant decreases in these treatments only occurred with fungal inhibition in the amino acid substrate treatments. These results demonstrate that in situ studies are required to better understand the dynamics of codenitrifcation substrates in grazed pasture soils and the associated role that fungi have with respect to codenitrifcation.
  • Roadmap for the European Joint Program SOIL: Towards Climate-Smart Sustainable Management of Agricultural Soils

    Saskia, Visser; Saskia, Keesstra; Órlaith, Ní Choncubhair; Titia, Mulder; Edoardo, Costantini; Francois, Sousanna Jean; Claire, Chenu; Peter, Kuikman; Jennie, Barron; Niels, Halberg; et al. (MDPI AG, 2020-06-23)
    Our planet suffers from humankind’s impact on natural resources, biogeochemical cycles and ecosystems. Intensive modern agriculture with inappropriate inputs of fertilisers, pesticides and fossil fuel –based energy has increasingly added to human pressure on the environment. As a key element of our natural capital, soils are also under threat, despite being essential to provide food, feed, fibre and fuel for an increasing global population. Moreover, soils play a key role in carbon, water and energy cycles, highlighting their importance for biomass provision and the circular bioeconomy. Evidently, these new and complex challenges cannot be resolved effectively with existing knowledge and experience alone. These challenges require scientific research, interdisciplinary collaboration and networking to find context-specific and tailored solutions addressing societal issues of our time and facilitating the adoption of these solutions. The most effective approaches are based on the involvement of multiple actors from science, policy, economy, civil society and farming that have the same goal, work on the same societal issue, but have complementing backgrounds, expertise and perceptions. The European Joint Programme (EJP) SOIL is a European network of research institutes in the field of soil science and agricultural soil management that will provide science-based advice to practitioners and policymakers, at local, national and European level. The EJP SOIL aims to align and boost research, training and capacity building through joint programming activities co-funded by the European Commission and national research programs. This will reduce current fragmentation and help to find synergies in order to make a leapfrog in research on good agricultural soil management in three main areas: climate change mitigation and adaptation, production capacity in healthy food systems, and environmental sustainability. By joint programming, training and capacity building, EJP SOIL will also take into account the need for effective policy solutions, as well as the socio-economic conditions of all stakeholders in the agricultural value chain. Thus, a key focus of the EJP SOIL is to build and strengthen a framework for an integrated community of research groups working on related aspects of agricultural soil management. As part of this effort, EJP SOIL will co-construct with stakeholders a roadmap for agricultural soil research. To develop a structured roadmap, EJP SOIL works with a version of the knowledge management framework of Dalkir (2005). The EJP version uses four compartments: (i) Knowledge development, (ii) knowledge harmonisation, organisation and storage (iii) knowledge sharing and transfer, and (iv) knowledge application. The four segments are part of a cyclic process to enhance the development and use of knowledge on agricultural soils. Knowledge development comprises assessing new knowledge needs to achieve the expected impacts of EJP SOIL. Therefore, by involving multiple stakeholders, knowledge gaps across Europe will be identified to work towards the adoption of Climate-Smart Sustainable Agricultural Soil Management (CSSASM). Within the knowledge sharing and transfer compartment, the capacity of scientists, advisors, policy makers, farmers and other stakeholders will be strengthened. EJP SOIL will work to support networks and co-creation of new knowledge with stakeholder groups, stimulating innovation in CSSASM. The knowledge harmonization, organization and storage compartment of the knowledge framework ensures linkages with all stakeholders to guarantee data harmonization and standardization. The last compartment, application of knowledge, will be facilitated by creating better guidelines, awareness and capacity for Climate-Smart Sustainable Agricultural Soil Management adoption and by strengthening science-to-policy processes at EU and Member State level.
  • An Analysis of the Cost of the Abatement of Ammonia Emissions in Irish Agriculture to 2030

    Buckley, Cathal; Krol, Dominika; Lanigan, Gary J.; Donnellan, Trevor; Spink, John; Hanrahan, Kevin; Boland, Andy; Forrestal, Patrick; Humphreys, James; Murphy, Pat; et al. (Teagasc, 2020-09)
    This analysis quantifies the potential to abate national ammonia (NH3) emissions up to 2030. This report is an updated marginal abatement cost curve (MACC) analysis where Teagasc has quantified the abatement potential of a range of ammonia mitigation measures, as well as their associated costs/benefits (see Lanigan et al. 2015 for previous analysis). The objective of this analysis is to quantify the extent and costs associated with meeting future ammonia emission targets that were negotiated as part of the amended Clean Air Policy Package. The requirement to reduce ammonia emissions is urgent, both in terms of compliance with the National Emissions Ceilings Directive (NECD), and as a principal loss pathway for agricultural nitrogen (N). Improvement of N efficiency is a key focus for improving farm efficiency and sustainability as well as reducing the ammonia, nitrate and greenhouse gas (GHG) footprint of agriculture. This is particularly relevant in the context of the national strategies on the development of the agri-food sector: Food Wise 2025, Ag-food strategy 2030 and Ag-Climatise (currently under development) and the newly unveiled EU Farm to Fork Strategy, which is a part of the European Green Deal. Under the baseline scenario (S1), agricultural ammonia emissions are projected to increase by 9% (without any mitigation) by 2030 relative to 2005 levels. While these increases are small in comparison to the targeted increase in agricultural output, they will provide a major challenge to meeting emissions targets, particularly as agriculture comprises over 99% of national emissions. The analysis presented in this report seeks to quantify the ammonia mitigation potential under likely uptake pathways. This is not an exhaustive analysis of all mitigation measures, but represents an assessment of best available techniques, based on scientific, peer-reviewed research carried out by Teagasc and associated national and international research partners. Indeed, any future changes in the sector or in the national emission inventory calculations will require further analysis of the applicability of ammonia mitigation techniques, particularly in terms of housing and storage but also in the context of other reactive N1 emissions. It should also be noted that some mitigation measures, particularly those related to nitrogen application to soils, could result in either higher greenhouse gas emissions or higher nitrate leaching. Compared to a future where no mitigation measures are deployed to address emissions, by 2030 the average technical abatement2 potential was estimated to be approximately 15.26 kt NH3 at a net cost of €10.86 million per annum. However, it should be noted that the net cost (€10.86 million) is comprised of 6 measures that are cost negative (-€22.21 million) and 7 measures that are cost positive (€33.07) and that some of the cost negative measures are predicated on efficiency gains driven by best management practice adoption (e.g. liming and clover measures with associate chemical N reductions). Amongst the thirteen mitigation measures selected for this analysis, 80% of the mitigation potential can be achieved by the full implementation of the mitigation pathways for protected urea and low emission slurry spreading (LESS) techniques for bovines. It should be stressed that this is an assessment of the maximum abatement potential and realising this level of abatement in practice will be extremely challenging. Any increase in agricultural activity beyond the baseline scenario will increase absolute emissions. The level of mitigation achievable is based on the draft AgClimatise measures any delay or reduction in the uptake of these measures will reduce the mitigation achieved. It must also be ensured that all mitigation measures should, where possible, be synergistic with reductions in greenhouse gas emissions and N loss to water.

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