• Clay illuviation provides a long-term sink for C sequestration in subsoils

      Torres-Sallan, Gemma; Schulte, Rogier P.; Lanigan, Gary; Byrne, Kenneth; Reidy, Brian; Simó, Iolanda; Six, Johan; Creamer, Rachel; Irish Soil Information System project; Teagasc; et al. (Springer Nature, 2017-04-06)
      Soil plays a key role in the global carbon (C) cycle. Most current assessments of SOC stocks and the guidelines given by Intergovernmental Panel on Climate Change (IPCC) focus on the top 30 cm of soil. Our research shows that, when considering only total quantities, most of the SOC stocks are found in this top layer. However, not all forms of SOC are equally valuable as long-term stable stores of carbon: the majority of SOC is available for mineralisation and can potentially be re-emitted to the atmosphere. SOC associated with micro-aggregates and silt plus clay fractions is more stable and therefore represents a long-term carbon store. Our research shows that most of this stable carbon is located at depths below 30 cm (42% of subsoil SOC is located in microaggregates and silt and clay, compared to 16% in the topsoil), specifically in soils that are subject to clay illuviation. This has implications for land management decisions in temperate grassland regions, defining the trade-offs between primary productivity and C emissions in clay-illuviated soils, as a result of drainage. Therefore, climate smart land management should consider the balance between SOC stabilisation in topsoils for productivity versus sequestration in subsoils for climate mitigation.
    • Digital Soil Information System for Ireland – Scoping Study

      Daly, Karen M.; Fealy, Reamonn; Environmental Protection Agency (Environmental Protection Agency, 01/09/2007)
      Soil is our life support system, crucial for the production of food and biomass and critical for the sustainability of an agro–environmental economy. The authors suggest that it is axiomatic that Ireland should have ready access to its soil information through the benefits of modern information technology. Soil is a multifunctional and complex natural medium that provides ecosystem services such as the production of food, fibre and fuel, the provision of habitat, nutrient cycling, contaminant transformation, water cycling and climate regulation. Reports from the European Commission indicate that many of these functions and services are under threat and soil protection is now placed on the same level as that of water and air.
    • Digital Soil Mapping in the Irish Soil Information System

      Corstanje, R.; Mayr, T.; Fealy, Reamonn; Zawadzka, Joanna; Lopapa, G.; Creamer, Rachel E.; Schulte, Rogier P.; Environmental Protection Agency (International Union of Soil Sciences, 2009-12)
      Harmonised soil data across Europe with a 1:250 000 geo-referenced soil database will allow for exchange of data across member states and the provide the information needed by the European Commission and European Environment Agency for reporting on issues relating to soil quality under a fu-ture Soil Framework Directive. Within this context, the Environmental Protection Agency of the Republic of Ireland commissioned a project run by Teagasc to produce a 1:250 000 soil map of the Republic of Ire-land. Delivery of this map and associated database is a collaborative effort between Teagasc, the National Soil Resources Institute at Cranfield in the UK and University College Dublin.
    • Effect of Agricultural Practices on Nitrate Leaching

      Ryan, Michael; McNamara, Kevin; Brophy, C.; Connolly, John; Carton, Owen T.; Richards, Karl G.; Environmental Protection Agency (Teagasc, 01/12/2005)
      A farm-scale study, carried out at Teagasc, Moorepark (Curtin’s farm), examined the effect of four managements (treatments) on nitrate-nitrogen (NO3-N) leaching over the period 2001-`05. Leaching was measured in these treatments: (T1) plots receiving dirty water and N fertilizer which were grazed; (T2) 2-cut silage and grazing plots receiving slurry and fertilizer N; (T3) grazed plots receiving fertilizer N and (T4) 1-cut silage and grazing plots receiving slurry and fertilizer N. The soil is a free-draining sandy loam overlying Karstic fissured limestone. The mean direct N inputs (kg/ha) for T1-T4 in 2001-`04 were 311, 309, 326, 331, respectively, with stocking rates (LU/ha) of 2.12 - ~2.47. Eight ceramic cups per plot, in 3 replicate plots of each treatment, were used to collect water, on a weekly basis, from 1.0 m deep using 50 kPa suction. There were 33, 37, 26 and 24 sampling dates in the 4 years, respectively. The NO3-N and NH4-N concentrations (mg/l) were determined in the water samples. The annual average and weekly concentration of these parameters was statistically analysed for all years, using a repeated measures analysis. The aggregated data were not normally distributed. There was an interaction between treatment and year (p<0.001). Significant differences (p=0.05) in NO3-N concentrations showed between the treatments in years 1, 2, 4 but not in year 3. For the NH4-N data there was no interaction between treatment and year, p=0.12, or main effect of treatment, p=0.54 but there were differences between years, p=0.01. Mean weekly concentrations were analysed separately for each year. For NO3-N, in years 1, 2 and 4 there was an interaction between treatment and week (p<0.001). With NH4-N, there was an interaction between treatment and week in all 4 years. Dirty water was significantly higher than grazed and 1 cut silage in NO3-N concentrations in year 1; in year 2, dirty water and 2 cut silage were significantly higher than the other treatments while in year 4, dirty water and grazed were significantly higher than the other two treatments. The overall four-year weighted mean NO3-N and NH4-N concentrations were 8.2 and 0.297 mg/l. The NCYCLE (UK) model was adapted for Irish conditions as NCYCLE_IRL. The NCYCLE empirical approach proved to be suitable to predict N fluxes from Irish grassland systems in most situations. Experimental data appeared to agree quite well, in most cases, with the outputs from NCYCLE_IRL. The model was not capable of predicting data from some of the leaching experiments, which suggests that the observed leaching phenomena in these experiments could be governed by non-average conditions or other parameters not accounted for in NCYCLE_IRL. An approach that took into account denitrification, leaching and herbage yield would probably explain the differences found. NCYCLE_IRL proved to be a useful tool to analyse N leaching from grazed and cut grassland systems in Ireland.
    • Good water status: The integration of sustainable grassland production and water resources in Ireland

      Richards, Karl G.; Fenton, Owen; Khalil, Mohammed I.; Haria, Atul H.; Humphreys, James; Doody, Donnacha G.; Moles, Richard; Morgan, Ger; Jordan, Philip; Department of Agriculture, Food and the Marine, Ireland; et al. (School of Agriculture, Food Science and Veterinary Medicine, University College Dublin in association with Teagasc, 2009)
      The challenge for sustainable grassland production is to integrate economically profitable farming systems with environmental protection. The Water Framework Directive aims to attain at least “good status” for all waters by 2015, to be achieved through the introduction of measures across all sectors of society. Historically, the impact of grassland agriculture on water quality was investigated in isolation. More recently it has been highlighted that water quality and other environmental impacts such as greenhouse gas emissions must be considered in an integrated manner. Catchment hydrology is critical to understanding the drivers behind nutrient transport to surface water and groundwaters. Flashy catchments are more susceptible to phosphorus, sediment and ammonium loss, whereas contrastingly baseflow dominated catchments are more susceptible to nitrate transport. Understanding catchment hydrology enables the targeting of measures for the mitigation of diffuse agricultural contaminants. This increased understanding can also be used to support extended deadlines for the achievement of good status. This paper reviews the potential effects of grassland agriculture on water quantity and the transport of pesticides and nutrients to water in the context of achieving good status for all waters by 2015 under the Water Framework Directive.
    • The impact of grazing cattle on soil physical properties and nutrient concentrations in overland flow from pasture, Part B

      Kurz, Isabelle; O’Reilly, Conor; Tunney, Hubert; Bourke, David; Environmental Protection Agency (Teagasc, 01/06/2007)
      The loss of nutrients from agricultural land to water bodies is a serious concern in many countries. To gain information on the contribution of grazing animals to diffuse nutrient losses from pasture areas to water, this study looked at the impact of cattle on nutrient concentrations in overland flow and on soil hydrology (bulk density, macroporosity and resistance to penetration). Rainfall simulations to produce overland flow were conducted and soil physical measurements were taken on experimental plots assigned to one of two treatments: 1) cattle had unrestricted access to the plot; 2) cattle could graze the plot but they could neither walk on the plot area nor deposit excrements on it. Areas to which the cattle had free access were characterised by 57%-83% lower macroporosity, by 8%-17% higher bulk density and by 27%-50% higher resistance to penetration than areas from which the cattle were excluded. The nutrients in overland flow from grassland that were affected by the presence of grazing animals were mainly the particulate nitrogen, the organic phosphorus and the potassium concentrations. Overall, the presence of cattle had a longer lasting effect on the soil hydrological parameters measured than on the nutrient concentrations in overland flow.
    • The influence of aggregate size fraction and horizon position on microbial community composition

      Fox, Aaron; Ikoyi, Israel; Torres-Sallan, Gemma; Lanigan, Gary; Schmalenberger, Achim; Wakelin, Steve; Creamer, Rachel; Teagasc Walsh Fellowship Programme; Environmental Protection Agency; Agricultural GHG Research Initiative for Ireland; et al. (Elsevier, 2018-03-09)
      The influence of horizon position and aggregate size on bacterial and fungal community composition was determined. From nine sites, soils were collected from the top three horizon positions (H1, H2 and H3). Physical fractionation separated samples into large macroaggregate (LM, >2000 μm), macroaggregate (MAC, >250 μm), microaggregate (MIC, <250 μm), and silt and clay (SC, 53 μm) fractions. In all samples, the structure of the bacterial and fungal community composition was assessed via restriction fragment length polymorphism (T-RFLP), and for the four aggregate sizes from the top two horizons positions an in-depth analysis of the bacterial community was conducted using next generation sequencing (NGS). Bacterial and fungal communities both differed between aggregate-sizes. Changes in the composition of the bacterial and fungal communities also occurred among horizon positions, with a significant interaction between aggregate size and horizon position evident for the bacterial community. Using NGS, it was shown that aggregate-size had a significant effect on the bacterial community in both horizon positions at both the phyla and family taxonomic levels. MAC and MIC significantly differed in the % relative abundance of bacterial groups, potentially indicating differing predation pressures. These results indicate that both horizon position and aggregate size support distinct microbial communities. Understanding these parameters is critical in our comprehension of the patterns of microbial diversity in soil.
    • The interactive effects of fertiliser nitrogen with dung and urine on nitrous oxide emissions in grassland

      Hyde, Bernard; Forrestal, Patrick J.; Jahangir, Mohammad M. R.; Ryan, Michael; Fanning, A.; Carton, Owen T.; Lanigan, Gary; Richards, Karl G.; Environmental Protection Agency; Department of Agriculture, Food and the Marine, Ireland; et al. (Teagasc (Agriculture and Food Development Authority), Ireland, 08/09/2016)
      Nitrous oxide (N2O) is an important and potent greenhouse gas (GHG). Although application of nitrogen (N) fertiliser is a feature of many grazing systems, limited data is available on N2O emissions in grassland as a result of the interaction between urine, dung and fertiliser N. A small plot study was conducted to identify the individual and interactive effects of calcium ammonium nitrate (CAN) fertiliser, dung and urine. Application of CAN with dung and urine significantly increased the mass of N2O-N emission. Importantly, the sum of N2O-N emitted from dung and CAN applied individually approximated the emission from dung and CAN fertiliser applied together, that is, an additive effect. However, in the case of urine and CAN applied together, the emission was more than double the sum of the emission from urine and CAN fertiliser applied individually, that is, a multiplicative effect. Nitrous oxide emissions from dung, urine and fertiliser N are typically derived individually and these individual emission estimates are aggregated to produce estimates of N2O emission. The presented findings have important implications for how individual emission factors are aggregated; they suggest that the multiplicative effect of the addition of CAN fertiliser to urine patches needs to be taken into account to refine the estimation of N2O emissions from grazing grasslands.
    • Mapping Soils in Ireland

      Simo, Iolanda; Constanje, R.; Fealy, Reamonn; Hallett, S.; Hannam, Jacqueline; Holden, Nicholas M.; Jahns, G.; Jones, B.; Massey, P.; Mayr, T.; et al. (CRC Press, 2014)
      Harmonised soil data across Europe with a 1:250 000 geo-referenced soil database will allow for exchange of data across member states and the provide the information needed for reporting on issues re-lating to soil quality under a future Soil Framework Directive. The current status of soils data available in Eu-rope is inconsistent at best. The Irish Soil Information System (ISIS) project is currently developing a national soil map of 1:250,000 and an associated digital soil information system, providing both spatial and quantita-tive information on soil types and properties across Ireland. Both the map and the information system will be freely available to the public through a designated website.
    • Modelling soil bulk density at the landscape scale and its contributions to C stock uncertainty

      Taalab, K.P.; Corstanje, R.; Creamer, Rachel E.; Whelan, M. J.; Environmental Protection Agency (European Geosciences Union, 12/07/2013)
      Soil bulk density (Db) is a major contributor to uncertainties in landscape-scale carbon and nutrient stock estimation. However, it is time consuming to measure and is, therefore, frequently predicted using surrogate variables, such as soil texture. Using this approach is of limited value for estimating landscape-scale inventories, as its accuracy beyond the sampling point at which texture is measured becomes highly uncertain. In this paper, we explore the ability of soil landscape models to predict soil Db using a suite of landscape attributes and derivatives for both topsoil and subsoil. The models were constructed using random forests and artificial neural networks. Using these statistical methods, we have produced a spatially distributed prediction of Db on a 100 m × 100 m grid, which was shown to significantly improve topsoil carbon stock estimation. In comparison to using mean values from point measurements, stratified by soil class, we found that the gridded method predicted Db more accurately, especially for higher and lower values within the range. Within our study area of the Midlands, UK, we found that the gridded prediction of Db produced a stock inventory of over 1 million tonnes of carbon greater than the stratified mean method. Furthermore, the 95% confidence interval associated with total C stock prediction was almost halved by using the gridded method. The gridded approach was particularly useful in improving organic carbon (OC) stock estimation for fine-scale landscape units at which many landscape–atmosphere interaction models operate.
    • Nitrous Oxide Emissions

      Hyde, Bernard; Ryan, Mary; Hawkins, M.; Connolly, John; Carton, Owen T.; Environmental Protection Agency (Teagasc, 01/04/2005)
      Nitrous oxide (N2O) is one of the three most important greenhouse gases (GHG). Nitrous oxide emissions currently account for approximately one third of GHG emissions from agriculture in Ireland. Emissions of N2O arise naturally from soil sources and from the application of nitrogen (N) in the form of N fertilizers and N in dung and urine deposition by grazing animals at pasture. Nitrous oxide emission measurements were conducted at three different scales. Firstly, a large-scale field experiment was undertaken to compare emission rates from a pasture receiving three different rates of N fertilizer application and to identify the effects of controlling variables over a two-year period. Variation in emission rates was large both within and between years. Two contrasting climatic years were identified. The cooler and wetter conditions in year 1 gave rise to considerably lower emission levels than the warmer and drier year 2. However, in both years, peak emissions were associated with fertilizer N applications coincident with rainfall events in the summer months. A small-plot study was conducted to identify the individual and combined effects of fertilizer, dung and urine applications to grassland. Treatment effects were however, difficult to obtain due to the overriding effects of environmental variables. Thirdly, through the use of a small-scale mini-lysimeter study, the diurnal nature of N2O emission rates was identified for two distinct periods during the year. The occurrence of a diurnal pattern has important implications for the identification of a measurement period during the day which is representative of the true daily flux. The research presented aims to identify the nature and magnitude of N2O emissions and the factors which affect emission rates from a grassland in Ireland. Further work is required to integrate the effects of different soil types and contrasting climatic regimes across soil types on N2O emissions.
    • Pedotransfer functions for Irish soils – estimation of bulk density (ρb) per horizon type

      Reidy, Brian; Simo, Iolanda; Sills, P.; Creamer, Rachel E.; Environmental Protection Agency (European Geosciences Union, 18/01/2016)
      Soil bulk density is a key property in defining soil characteristics. It describes the packing structure of the soil and is also essential for the measurement of soil carbon stock and nutrient assessment. In many older surveys this property was neglected and in many modern surveys this property is omitted due to cost both in laboratory and labour and in cases where the core method cannot be applied. To overcome these oversights pedotransfer functions are applied using other known soil properties to estimate bulk density. Pedotransfer functions have been derived from large international data sets across many studies, with their own inherent biases, many ignoring horizonation and depth variances. Initially pedotransfer functions from the literature were used to predict different horizon type bulk densities using local known bulk density data sets. Then the best performing of the pedotransfer functions were selected to recalibrate and then were validated again using the known data. The predicted co-efficient of determination was 0.5 or greater in 12 of the 17 horizon types studied. These new equations allowed gap filling where bulk density data were missing in part or whole soil profiles. This then allowed the development of an indicative soil bulk density map for Ireland at 0–30 and 30–50 cm horizon depths. In general the horizons with the largest known data sets had the best predictions, using the recalibrated and validated pedotransfer functions.
    • Real-time forecasting of pesticide concentrations in soil

      McGrath, Gavan; Rao, P. Suresh C.; Mellander, Per-Erik; Kennedy, Ivan; Rose, Michael; van Zwieten, Lukas; Grains Research and Development Corporation grant; Lee A. Reith Endowment in the Lyles School of Civil Engineering at Purdue University; Environmental Protection Agency; DAN00180; et al. (Elsevier, 2019-01-31)
      Forecasting pesticide residues in soils in real time is essential for agronomic purposes, to manage phytotoxic effects, and in catchments to manage surface and ground water quality. This has not been possible in the past due to both modelling and measurement constraints. Here, the analytical transient probability distribution (pdf) of pesticide concentrations is derived. The pdf results from the random ways in which rain events occur after pesticide application. First-order degradation kinetics and linear equilibrium sorption are assumed. The analytical pdfs allow understanding of the relative contributions that climate (mean storm depth and mean rainfall event frequency) and chemical (sorption and degradation) properties have on the variability of soil concentrations into the future. We demonstrated the two uncertain reaction parameters can be constrained using Bayesian methods. An approach to a Bayesian informed forecast is then presented. With the use of new rapid tests capable of providing quantitative measurements of soil concentrations in the field, real-time forecasting of future pesticide concentrations now looks possible for the first time. Such an approach offers new means to manage crops, soils and water quality, and may be extended to other classes of pesticides for ecological risk assessment purposes.
    • The short-term effects of management changes on watertable position and nutrients in shallow groundwater in a harvested peatland forest

      Finnegan, Joanne; Regan, J. T.; Fenton, Owen; Lanigan, Gary; Brennan, Raymond B.; Healy, Mark G.; Environmental Protection Agency; Department of Agriculture, Food and the Marine, Ireland (Elsevier, 08/05/2014)
      Management changes such as drainage, fertilisation, afforestation and harvesting (clearfelling) of forested peatlands influence watertable (WT) position and groundwater concentrations of nutrients. This study investigated the impact of clearfelling of a peatland forest on WT and nutrient concentrations. Three areas were examined: (1) a regenerated riparian peatland buffer (RB) clearfelled four years prior to the present study (2) a recently clearfelled coniferous forest (CF) and (3) a standing, mature coniferous forest (SF), on which no harvesting took place. The WT remained consistently below 0.3 m during the pre-clearfelling period. Results showed there was an almost immediate rise in the WT after clearfelling and a rise to 0.15 m below ground level (bgl) within 10 months of clearfelling. Clearfelling of the forest increased dissolved reactive phosphorus concentrations (from an average of 28–230 μg L−1) in the shallow groundwater, likely caused by leaching from degrading brash mats.
    • TaLAM: Mapping Land Cover in Lowlands and Uplands with Satellite Imagery

      Cawkwell, Fiona; Raab, Christoph; Barrett, Brian; green, stuart; Finn, John; Environmental Protection Agency (Environmental Protection Agency, 2018-07)
      The Towards Land Cover Accounting and Monitoring (TaLAM) project is part of Ireland’s response to creating a national land cover mapping programme. Its aims are to demonstrate how the new digital map of Ireland, Prime2, from Ordnance Survey Ireland (OSI), can be combined with satellite imagery to produce land cover maps.