• Countdown to 2010: Can we assess Ireland’s insect species diversity and loss?

      Regan, Eugenie; Nelson, Brian; McCormack, Stephen; Nash, Robert; O'Connor, James P (Royal Irish Academy, 03/09/2010)
      The insects are the most diverse organisms on this planet and play an essential role in ecosystem functioning, yet we know very little about them. In light of the Convention on Biological Diversity, this paper summarises the known insect species numbers for Ireland and questions whether this is a true refl ection of our insect diversity. The total number of known species for Ireland is 11,422. Using species accumulation curves and a comparison with the British fauna, this study shows that the Irish list is incomplete and that the actual species number is much higher. However, even with a reasonable knowledge of the species in Ireland, insects are such speciose, small, and inconspicuous animals that it is diffi cult to assess species loss. It is impossible to know at one point in time the number of insect species in Ireland and, although it is useful to summarise the known number of species, it is essential that biodiversity indicators, such as the Red List Index, are developed.
    • Data and code: Beneficial effects of multi-species mixtures on N2O emissions from intensively managed grassland swards

      Cummins, Saoirse; Finn, John; Richards, Karl; Lanigan, Gary; Grange, Guylain; Brophy, Caroline; Cardenas, Laura M.; Misselbrook, Tom H.; Reynolds, Chris K.; Krol, Dominika; et al. (2021)
      We provide the data and statistical code that produced the results presented in Cummins et al. (2021). Three files are available to download: - The data file ‘Cummins_etal_2021_N2O.csv’: contains the annual N2O emissions and N2O emissions intensities (see Readme file for details) measured from sown grassland comprising one to six species within one to three functional groups (grass, legume and herb). - An accompanying readme file ‘Readme_Cummins_etal_2021_N2O.txt’: this contains the metadata for the data in ‘Cummins_etal_2021_N2O.csv’. - Statistical code (SAS software) ‘SAScode_for_Cummins_et_al_2021.sas’: SAS code to repeat the analyses as in the final models of the published paper.
    • Data file: confusion matrices from pilot study of methodology for the development of farmland habitat reports for sustainability assessments

      Finn, John; Moran, Patrick; Teagasc; 6793 (2020-03-09)
      This Excel data file provides the confusion matrices associated with a publication in the Irish Journal of Agricultural and Food Research. This file contains four worksheets: 'High vs Low matrix', 'Level II matrix', 'Level III matrix' and 'Level III matrix (HH)'. Each worksheet presents the area of different habitat classes (as in Fossitt 2000) as determined by a desk-based study of remote sensing imagery, and compared with area of habitat classes as determined by a field-based survey (ground-truthing). The publication by John A. Finn and Patrick Moran is titled 'A pilot study of methodology for the development of farmland habitat reports for sustainability assessments'.
    • Denitrification and indirect N2O emissions in groundwater: Hydrologic and biogeochemical influences

      Jahangir, Mohammad M. R.; Johnston, Paul; Barrett, Maria; Khalil, Mohammed I.; Groffman, P.M.; Boeckx, P.; Fenton, Owen; Murphy, John; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; et al. (Elsevier, 08/07/2013)
      Identification of specific landscape areas with high and low groundwater denitrification potential is critical for improved management of agricultural nitrogen (N) export to ground and surface waters and indirect nitrous oxide (N2O) emissions. Denitrification products together with concurrent hydrogeochemical properties were analysed over two years at three depths at two low (L) and two high (H) permeability agricultural sites in Ireland. Mean N2O–N at H sites were significantly higher than L sites, and decreased with depth. Conversely, excess N2–N were significantly higher at L sites than H sites and did not vary with depth. Denitrification was a significant pathway of nitrate (NO3−–N) reduction at L sites but not at H sites, reducing 46–77% and 4–8% of delivered N with resulting mean NO3−–N concentrations of 1–4 and 12–15 mg N L− 1 at L and H sites, respectively. Mean N2O–N emission factors (EF5g) were higher than the most recent Intergovernmental Panel on Climate Change (IPCC, 2006) default value and more similar to the older IPCC (1997) values. Recharge during winter increased N2O but decreased excess dinitrogen (excess N2–N) at both sites, probably due to increased dissolved oxygen (DO) coupled with low groundwater temperatures. Denitrifier functional genes were similar at all sites and depths. Data showed that highly favourable conditions prevailed for denitrification to occur — multiple electron donors, low redox potential (Eh < 100 mV), low DO (< 2 mg L− 1), low permeability (ks < 0.005 m·d− 1) and a shallow unsaturated zone (< 2 m). Quantification of excess N2–N in groundwater helps to close N balances at the local, regional and global scales.
    • Denitrification potential in subsoils: A mechanism to reduce nitrate leaching to groundwater

      Jahangir, Mohammad M. R.; Khalil, Mohammed I.; Johnston, Paul; Cardenas, L. M.; Hatch, D.J.; Butler, Mark; Barrett, Maria; O'Flaherty, Vincent; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; et al. (Elsevier, 28/05/2011)
      Understanding subsurface denitrification potential will give greater insights into landscape nitrate (NO3−) delivery to groundwater and indirect nitrous oxide (N2O) emissions to the atmosphere. Potential denitrification rates and ratios of N2O/(N2O + N2) were investigated in intact soil cores collected from 0–0.10, 0.45–0.55 and 1.20–1.30 m depths representing A, B and C soil horizons, respectively from three randomly selected locations within a single intensively managed grazed grassland plot in south eastern Ireland. The soil was moderately well drained with textures ranging from loam to clay loam (gleysol) in the A to C horizon. An experiment was carried out by amending soils from each horizon with (i) 90 mg NO3−–N as KNO3, (ii) 90 mg NO3−–N + 150 mg glucose-C, (iii) 90 mg NO3−–N + 150 mg DOC (dissolved organic carbon, prepared using top soil of intensively managed grassland) kg−1 dry soil. An automated laboratory incubation system was used to measure simultaneously N2O and N2, at 15 ◦C, with the moisture content raised by 3% (by weight) above the moisture content at field capacity (FC), giving a water-filled pore space (WFPS) of 80, 85 and 88% in the A, B and C horizons, respectively. There was a significant effect (p < 0.01) of soil horizon and added carbon on cumulative N2O emissions. N2O emissions were higher from the A than the B and C horizons and were significantly lower from soils that received only nitrate than soils that received NO3 − + either of the C sources. The two C sources gave similar N2O emissions. The N2 fluxes differed significantly (p < 0.05) only between the A and C horizons. During a 17-day incubation, total denitrification losses of the added N decreased significantly (p < 0.01) with soil depth and were increased by the addition of either C source. The fraction of the added N lost from each horizon were A: 25, 61, 45%; B: 12, 29, 28.5% and C: 4, 20, 18% for nitrate, nitrate + glucose-C and nitrate + DOC, respectively. The ratios of N2O to N2O + N2 differed significantly (p < 0.05) only between soil horizons, being higher in the A (0.58–0.75) than in the deeper horizons (0.10–0.36 in B and 0.06–0.24 in C), clearly indicating the potential of subsoils for a more complete reduction of N2O to N2. Stepwise multiple regression analysis revealed that N2O flux increased with total organic C and total N but decreased with NO3 −–N which together explained 88% of the variance (p < 0.001). The N2 flux was best explained (R2 = 0.45, p < 0.01) by soluble organic nitrogen (SON) (positive) and with NO3−–N (negative). Stepwise multiple regression revealed a best fit for total denitrification rates which were positive for total C and negative for NO3 −–N with the determination coefficient of 0.76 (p < 0.001). The results suggest that without C addition, potential denitrification rate below the root zone was low. Therefore, the added C sources in subsoils can satisfactorily increase nitrate depletion via denitrification where the mole fraction of N2O would be further reduced to N2 during diffusional transport through the soil profile to the atmosphere and/or to groundwater. Subsoil denitrification can be accelerated either through introducing C directly into permeable reactive barriers and/or indirectly, by irrigating dirty water and manipulating agricultural plant composition and diversity.
    • Determination and Occurrence of Phenoxyacetic Acid Herbicides and Their Transformation Products in Groundwater Using Ultra High Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

      McManus, Sarah-Louise; Moloney, Mary; Richards, Karl G.; Coxon, Catherine E.; Danaher, Martin; Teagasc Walsh Fellowship Programme; Department of Agriculture, Food and the Marine, Ireland (MDPI AG., Basel, Switzerland, 10/12/2014)
      A sensitive method was developed and validated for ten phenoxyacetic acid herbicides, six of their main transformation products (TPs) and two benzonitrile TPs in groundwater. The parent compounds mecoprop, mecoprop-p, 2,4-D, dicamba, MCPA, triclopyr, fluroxypr, bromoxynil, bentazone, and 2,3,6-trichlorobenzoic acid (TBA) are included and a selection of their main TPs: phenoxyacetic acid (PAC), 2,4,5-trichloro-phenol (TCP), 4-chloro-2-methylphenol (4C2MP), 2,4-dichlorophenol (DCP), 3,5,6-trichloro-2-pyridinol (T2P), and 3,5-dibromo-4-hydroxybenzoic acid (BrAC), as well as the dichlobenil TPs 2,6-dichlorobenzamide (BAM) and 3,5-dichlorobenzoic acid (DBA) which have never before been determined in Irish groundwater. Water samples were analysed using an efficient ultra-high performance liquid chromatography (UHPLC) method in an 11.9 min separation time prior to detection by tandem mass spectrometry (MS/MS). The limit of detection (LOD) of the method ranged between 0.00008 and 0.0047 µg·L−1 for the 18 analytes. All compounds could be detected below the permitted limits of 0.1 µg·L−1 allowed in the European Union (EU) drinking water legislation [1]. The method was validated according to EU protocols laid out in SANCO/10232/2006 with recoveries ranging between 71% and 118% at the spiked concentration level of 0.06 µg·L−1. The method was successfully applied to 42 groundwater samples collected across several locations in Ireland in March 2012 to reveal that the TPs PAC and 4C2MP were detected just as often as their parent active ingredients (a.i.) in groundwater.
    • Development of a scoring method to identify important areas of plant diversity in Ireland

      Walsh, Aidan; Sullivan, C. A.; Waldren, Stephen; Finn, John; Irish Research Council; Teagasc Walsh Fellowship Programme; PD/2011/2150; 2011012 (Elsevier, 2018-10-28)
      In the face of accelerating biodiversity loss it is more important than ever to identify important areas of biodiversity and target limited resources for conservation. We developed a method to identify areas of important plant diversity using known species’ distributions and evaluations of the species importance. We collated distribution records of vascular plants and developed a scoring method of spatial prioritisation to assign conservation value to the island of Ireland at the hectad scale (10 km × 10 km) and at the tetrad scale (2 km × 2 km) for two counties where sufficient data were available. Each plant species was assigned a species conservation value based on both its conservation status and distribution in Ireland. For each cell, the species conservation values within the cell were summed, thereby differentiating between areas of high and low conservation value across the landscape. Areas with high conservation value represent the most important areas for plant conservation. The protected area cover and the number of species present in these important areas were also examined by first defining threshold values using two different criteria. Species representation was high in the important areas; the identified important areas of plant diversity maintained high representation of species of conservation concern and achieved high species representation overall, requiring a low number of sites (<8%) to do so. The coincidence of protected areas and important areas for plant diversity was found to be low and while some important areas of plant diversity might benefit from the general protection afforded by these areas, our research highlights the need for conservation outside of protected areas.
    • 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.
    • Distribution and extent of High Nature Value farmland in the Republic of Ireland (tetrad scale)

      Matin, Shafique; Sullivan, C. A.; Finn, John; O hUallachain, Daire; green, stuart; Meredith, David; Moran, James (2019-05-06)
      High Nature Value (HNV) farmland is extensively managed farmland that has high biodiversity. This farmland is important for the conservation of semi-natural habitats and the plants and animals linked with them. Supporting this type of farmland will ensure high levels of farmland biodiversity, vibrant rural communities, high water, air and soil quality and resistance to flooding among other things. To map the likely distribution of HNV farmland in the Republic of Ireland (ROI) we used five indicators adapted for the Irish context and weighted based on expert knowledge and literature. The indicators used are: semi-natural habitat cover (CORINE land cover), stocking density (Land parcel information system), hedgerow/scrub cover (Teagasc), river and stream density (OSI), and soil diversity (Teagasc). Indicator data sets were included in a weighted sum model that combined raster indicator inputs, representing relative weights and the output HNV farmland had a tetrad-scale (2 km × 2 km) spatial resolution.
    • Easy phylotyping of Escherichia coli via the EzClermont web app and command-line tool

      Waters, Nicholas R.; Abram, Florence; Brennan, Fiona; Holmes, Ashleigh; Pritchard, Leighton; The James Hutton Institute; National University of Ireland, Galway (Microbiology Society, 2020-09-01)
      The Clermont PCR method for phylotyping Escherichia coli remains a useful classification scheme even though genome sequencing is now routine, and higher-resolution sequence typing schemes are now available. Relating present-day whole-genome E. coli classifications to legacy phylotyping is essential for harmonizing the historical literature and understanding of this important organism. Therefore, we present EzClermont – a novel in silico Clermont PCR phylotyping tool to enable ready application of this phylotyping scheme to whole-genome assemblies. We evaluate this tool against phylogenomic classifications, and an alternative software implementation of Clermont typing. EzClermont is available as a web app at www.ezclermont.org, and as a command-line tool at https://nickp60.github.io/EzClermont/.
    • The ecology of the European badger (Meles meles) in Ireland: a review

      Byrne, Andrew W.; Sleeman, D. Paddy; O'Keeffe, James; Davenport, John; Department of Agriculture, Food and the Marine, Ireland; Teagasc Walsh Fellowship Programme (Royal Irish Academy, 30/04/2012)
      The badger is an ecologically and economically important species. Detailed knowledge of aspects of the ecology of this animal in Ireland has only emerged through research over recent decades. Here, we review what is known about the species' Irish populations and compare these findings with populations in Britain and Europe. Like populations elsewhere, setts are preferentially constructed on south or southeast facing sloping ground in well-drained soil types. Unlike in Britain, Irish badger main setts are less complex and most commonly found in hedgerows. Badgers utilise many habitat types, but greater badger densities have been associated with landscapes with high proportions of pasture and broadleaf woodlands. Badgers in Ireland tend to have seasonally varied diets, with less dependence on earthworms than some other populations in northwest Europe. Recent research suggests that females exhibit later onset and timing of reproductive events, smaller litter sizes and lower loss of blastocysts than populations studied in Britain. Adult social groups in Ireland tend to be smaller than in Britain, though significantly larger than social groups from continental Europe. Although progress has been made in estimating the distribution and density of badger populations, national population estimates have varied widely in the Republic of Ireland. Future research should concentrate on filling gaps in our knowledge, including population models and predictive spatial modelling that will contribute to vaccine delivery, management and conservation strategies.
    • Ecosystem function enhanced by combining four functional types of plant species in intensively-managed grassland mixtures: a three-year continental-scale field experiment

      Finn, John; Kirwan, Laura; Connolly, John; Sebastia, Maria Teresa; Helgadottir, Aslaug; Baadshaug, Ole; Belanger, Gilles; Black, Alistair D; Brophy, C.; Collins, Rosemary; et al. (Wiley-Blackwell, 22/02/2013)
      1. A co-ordinated continental-scale field experiment across 31 sites was used to compare the biomass yield of monocultures and four-species mixtures associated with intensively managed agricultural grassland systems. To increase complementarity in resource use, each of the four species in the experimental design represented a distinct functional type derived from two levels of each of two functional traits, nitrogen acquisition (N2-fixing legume or non-fixing grass) crossed with temporal development (fast-establishing or temporally persistent). Relative abundances of the four functional types in mixtures were systematically varied at sowing to vary the evenness of the same four species in mixture communities at each site, and sown at two levels of seed density. 2. Across multiple years, the total yield (including weed biomass) of the mixtures exceeded that of the average monoculture in >97% of comparisons. It also exceeded that of the best monoculture (transgressive overyielding) in about 60% of sites, with a mean yield ratio of mixture to best-performing monoculture of 1.07 across all sites. Analyses based on yield of sown species only (excluding weed biomass) demonstrated considerably greater transgressive overyielding (significant at about 70% of sites, ratio of mixture to best-performing monoculture = 1.18). 3. Mixtures maintained a resistance to weed invasion over at least three years. In mixtures, median values indicate <4% of weed biomass in total yield, whereas the median percentage of weeds in monocultures increased from 15% in year 1 to 32% in year 3. 4. Within each year, there was a highly significant relationship (P<0.0001) between sward evenness and the diversity effect (excess of mixture performance over that predicted from the monoculture performances of component species). At lower evenness values, increases in community evenness resulted in an increased diversity effect, but the diversity effect was not significantly different from the maximum diversity effect across a wide range of higher evenness values. The latter indicates the robustness of the diversity effect to changes in species’ relative abundances. 5. Across sites with three complete years of data (24 of the 31 sites), the effect of interactions between the fast-establishing and temporal persistent trait levels of temporal development was highly significant and comparable in magnitude to effects of interactions between N2-fixing and non-fixing trait levels of nitrogen acquisition. 6. Synthesis and applications. The design of grassland mixtures is relevant to farm-level strategies to achieve sustainable intensification. Experimental evidence indicated significant yield benefits of four-species agronomic mixtures which yielded more than the highest-yielding monoculture at most sites. The results are relevant for agricultural practice, and show how grassland mixtures can be designed to improve resource complementarity, increase yields and reduce weed invasion. The yield benefits were robust to considerable changes in the relative proportions of the four species, which is extremely useful for practical management of grassland swards.
    • 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.
    • Effect of an agri-environmental measure on nitrate leaching from a beef farming system in Ireland

      Richards, Karl G.; Jahangir, Mohammad M. R.; Drennan, Michael J; Lenehan, J.J.; Connolly, John; Brophy, C.; Carton, Owen T. (Elsevier, 07/01/2015)
      Agricultural nitrogen (N) management remains a key environmental challenge. Improving N management is a matter of urgency to reduce the serious ecological consequences of the reactive N. Nitrate (NO3−–N) leaching was measured under suckler beef production systems stocked at two intensities: (1) intensive, 210 kg organic N ha−1 with two cut silage harvests; and (2) rural environmental protection scheme (REPS), 170 kg organic N ha−1 with one cut silage harvest. Three replicate plots of each treatment were instrumented with ceramic cups (8 per plot), randomly placed within each plot at a depth of 1 m to collect soil solution for NO3−–N at 50 kPa suction to collecting vessels one week prior to sampling. Samples were taken on a total of 53 sampling dates over 3 winter drainage periods (2002/03, 2003/04 and 2004/05). Over the course of the experiment the mean annual soil solution NO3−–N concentration exceeded the MAC twice out of 15 means (5 treatments over 3 years). The REPS grazing and silage sub treatments had significantly lower mean annual soil solution total oxidized N (TON) concentrations than the respective intensive treatments in years 2 and 3. Annual total NO3−–N losses over the three years in intensive and REPS systems ranged from 55 to 71 and 15 to 20 kg N ha−1, respectively. Mean N surpluses in intensive and REPS systems were 210 and 95 kg ha−1, respectively with the corresponding mean N inputs of 272 and 124 kg N ha−1. The reduction in N inputs under the REPS system results in lower N leaching losses and contributed to a significant reduction in pressures on water quality.
    • The effect of cattle slurry in combination with nitrate and the nitrification inhibitor dicyandiamide on in situ nitrous oxide and dinitrogen emissions

      McGeough, K. L.; Laughlin, Ronald J.; Watson, C. J.; Muller, Christoph; Ernfors, M.; Cahalan, E.; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; RSF 07 519 (European Geosciences Union, 04/12/2012)
      A field study was conducted to determine the effect of the nitrification inhibitor dicyandiamide (DCD) on N2O and N2 emissions after cattle slurry (CS) application in the presence of nitrate (NO3) fertiliser on seven different occasions (between March 2009 and March 2011). N2O emissions from CS in the presence of NO3 fertiliser were very high (0.4–8.7% of applied N) over a 20-day period, under mild moist conditions. Emissions were significantly larger from the CS treatment compared to an NH4+-N source, supplying the same rate of N as in the slurry. This study supports the view that organic fertilisers should not be applied at the same time as nitrate-based fertilisers, as significant increases in N2O emissions occur. The average N2O mole fraction (N2O/(N2O + N2)) over all seven application dates was 0.34 for CSNO3 compared to 0.24 for the NH4ClNO3 treatment, indicating the dominance of N2 emissions. The rate of nitrification in CSNO3 was slower than in NH4ClNO3, and DCD was found to be an effective nitrification inhibitor in both treatments. However, as N2O emissions were found to be predominantly associated with the NO3 pool, the effect of DCD in lowering N2O emissions is limited in the presence of a NO3 fertiliser. To obtain the maximum cost-benefit of DCD in lowering N2O emissions, under mild moist conditions, it should not be applied to a nitrate containing fertiliser (e.g. ammonium nitrate or calcium ammonium nitrate), and therefore the application of DCD should be restricted to ammonium-based organic or synthetic fertilisers.
    • Effect of chemical amendments to dairy soiled water and time between application and rainfall on phosphorus and sediment losses in runoff

      Serrenho, Ana; Fenton, Owen; Murphy, Paul N. C.; Grant, Jim; Healy, Mark G.; Department of Agriculture, Food and the Marine, Ireland; RSF 07 525 (Elsevier, 15/07/2012)
      Dairy soiled water (DSW) is a dilute, low nutrient effluent produced on Irish dairy farms through the regular washing down of milking parlours and holding areas. In Ireland, there is no closed period for the land application of DSW except where heavy rain is forecast within 48 h. Chemical amendments have the potential to decrease phosphorus (P) and suspended sediment (SS) loss from DSW applied to land. This study examined the impact of three time intervals (12, 24 and 48 h) between DSW application and rainfall and five treatments (control, unamended DSW, and DSW amended with lime, alum or ferric chloride (FeCl2)) on P and sediment losses from an intact grassland soil in runoff boxes. Rainfall was simulated at 10.5 ± 1 mm h− 1. Phosphorus concentrations (1–1.6 mg L− 1) in runoff from DSW application, while not quantitative measures of P loss to surface waters in the field, indicated the importance of incidental P losses and that the current 48 h restriction in Ireland is prudent. Unamended DSW application increased P loss by, on average, 71%, largely due to an increase in particulate phosphorus (PP) loss. All three amendments were effective in decreasing P and SS losses in runoff and, apart from the SS results for lime, were significantly different (p < 0.05) to the control at at least one time point. Lime (a 64% reduction in total phosphorus (TP) in comparison with DSW only) was less effective than alum or FeCl2, likely due to the lower solubility of CaCO3 in water. Chemical amendment showed potential to decrease P losses from land application of DSW, but the efficacy of such amendments would need to be assessed in field trials and a cost–benefit analysis conducted to further examine whether they could be practically implemented on farms.
    • The Effect of Chemical Amendments Used for Phosphorus Abatement on Greenhouse Gas and Ammonia Emissions from Dairy Cattle Slurry: Synergies and Pollution Swapping

      Brennan, Raymond B.; Healy, Mark G.; Fenton, Owen; Lanigan, Gary; European Union; Teagasc Walsh Fellowship Programme; FP7-KBBE-2010-4 (PLoS, 08/06/2015)
      Land application of cattle slurry can result in incidental and chronic phosphorus (P) loss to waterbodies, leading to eutrophication. Chemical amendment of slurry has been proposed as a management practice, allowing slurry nutrients to remain available to plants whilst mitigating P losses in runoff. The effectiveness of amendments is well understood but their impacts on other loss pathways (so-called ‘pollution swapping’ potential) and therefore the feasibility of using such amendments has not been examined to date. The aim of this laboratory scale study was to determine how the chemical amendment of slurry affects losses of NH3, CH4, N2O, and CO2. Alum, FeCl2, Polyaluminium chloride (PAC)- and biochar reduced NH3 emissions by 92, 54, 65 and 77% compared to the slurry control, while lime increased emissions by 114%. Cumulative N2O emissions of cattle slurry increased when amended with alum and FeCl2 by 202% and 154% compared to the slurry only treatment. Lime, PAC and biochar resulted in a reduction of 44, 29 and 63% in cumulative N2O loss compared to the slurry only treatment. Addition of amendments to slurry did not significantly affect soil CO2 release during the study while CH4 emissions followed a similar trend for all of the amended slurries applied, with an initial increase in losses followed by a rapid decrease for the duration of the study. All of the amendments examined reduced the initial peak in CH4 emissions compared to the slurry only treatment. There was no significant effect of slurry amendments on global warming potential (GWP) caused by slurry land application, with the exception of biochar. After considering pollution swapping in conjunction with amendment effectiveness, the amendments recommended for further field study are PAC, alum and lime. This study has also shown that biochar has potential to reduce GHG losses arising from slurry application.
    • Effect of organic, conventional and mixed cultivation practices on soil microbial community structure and nematode abundance in a cultivated onion crop

      Reilly, Kim; Cullen, Eileen; Lola-Luz, Theodora; Stone, Dote; Valverde, Juan; Gaffney, Michael; Brunton, Nigel; Grant, Jim; Griffiths, Bryan; Department of Agriculture, Food and the Marine, Ireland; et al. (Wiley, 07/06/2013)
      BACKGROUND: Responses of the soil microbial and nematode community to organic and conventional agricultural practices were studied using the Teagasc Kinsealy Systems Comparison trial as the experimental system. The trial is a long term field experiment which divides conventional and organic agriculture into component pest-control and soil treatment practices. We hypothesised that management practices would affect soil ecology and used community level physiological profiles (CLPP), microbial and nematode counts, and denaturing gradient gel electrophoresis (DGGE) to characterise soil microbial communities in plots used for onion (Allium cepa L.) cultivation. RESULTS: Microbial activity and culturable bacterial counts were significantly higher under fully organic management. Culturable fungi, actinomycete and nematode counts showed a consistent trend towards higher numbers under fully organic management but these data were not statistically significant. No differences were found in the fungal/bacterial ratio. DGGE banding patterns and sequencing of excised bands showed clear differences between treatments. Putative onion fungal pathogens were predominantly sequenced under conventional soil treatment practices whilst putative soil suppressive bacterial species were predominantly sequenced from the organic pest-control treatment plots. CONCLUSION: Organic management increased microbial activity and diversity. Sequence data was indicative of differences in functional groups and warrants further investigation.
    • The effect of precipitation and application rate on dicyandiamide persistence and efficiency in two Irish grassland soils

      Cahalan, E.; Minet, E.; Emfors, M.; Muller, Christoph; Devaney, D.; Forrestal, Patrick J.; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; RSF 07519; RSF 07545 (Wiley, 14/07/2015)
      The nitrification inhibitor dicyandiamide (DCD) has had variable success in reducing nitrate (NO3-) leaching and nitrous oxide (N2O) emissions from soils receiving nitrogen (N) fertilisers. Factors such as soil type, temperature and moisture have been linked to the variable efficacy of DCD. Since DCD is water soluble it can be leached from the rooting zone where it is intended to inhibit nitrification. Intact soil columns (15 cm diameter by 35 cm long) were taken from luvic gleysol and haplic cambisol grassland sites and placed in growth chambers. DCD was applied at 15 or 30 kg DCD ha-1, with high or low precipitation. Leaching of DCD, mineral N and the residual soil DCD concentrations were determined over eight weeks High precipitation increased DCD in leachate and decreased recovery in soil. A soil x DCD rate interaction was detected for the DCD unaccounted (proxy for degraded DCD). In the cambisol degradation of DCD was high (circa 81%) and unaffected by DCD rate. In contrast DCD degradation in the gleysol was lower and differentially affected by rate, 67 and 46% for the 15 and 30 kg ha-1 treatments, respectively. Differences DCD degradation rates between soils may be related to differences in organic matter content and associated microbiological activity. Variable degradation rates of DCD in soil, unrelated to temperature or moisture, may contribute to varying DCD efficacy. Soil properties should be considered when tailoring DCD strategies for improving nitrogen use efficiency and crop yields, through the reduction of reactive nitrogen loss.