• Unsaturated zone travel time to groundwater on a vulnerable site

      Richards, Karl G.; Coxon, Catherine E.; Ryan, Michael (Taylor & Francis, 2005)
      A bromide (Br) tracing experiment was conducted to ascertain unsaturated zone travel time to groundwater on a site with a karstified limestone aquifer overlain by a thin free-draining overburden. Br tracer was applied to areas surrounding two boreholes; soil solution and groundwater Br concentrations were monitored. Bromide was first detected after eight and 34 days in the soil solution and groundwater. The quick break-through of the applied Br in the soil solution and groundwater indicates the presence of preferential flow in the soil at this site. The time to maximum groundwater Br concentration supports a dominant matrix flow path through the overburden and then preferential flow through the unsaturated limestone bedrock. The results indicated that the transport of conservative contaminants, such as nitrate, can be expected to occur in a single recharge season. The occurrence of preferential flow raises concerns over rapid transport of non-conservative contaminants such as faecal coliforms and this merits further investigation.
    • Urine patch distribution under dairy grazing at three stocking rates in Ireland

      Dennis, S.J.; Moir, James L.; Cameron, K.C.; Di, H.J.; Hennessy, Deirdre; Richards, Karl G. (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      Nitrate pollution of water is a serious global environmental issue. Grassland agriculture is a major source of diffuse nitrate pollution, with much of this nitrate originating from the urine patches of grazing animals. To study nitrate losses from grassland it is necessary to consider the areas of grassland that are affected by urine separately from the remainder of the pasture. Urine patches can be observed in the field as areas of vigorously growing pasture, however the pasture may continue to respond for several months, making it difficult to determine when the observed patch was actually deposited. A global positioning system was used to record the location of all urine and dung patches in a pasture at every second grazing on an Irish dairy farm during the grazing season. Any patches reappearing were removed from the data, allowing the fresh urine patches to be identified. Dairy cows deposited 0.359 urine patches per grazing hour, a value that may be used to predict the distribution of urine patches under any grazing regime. This equated to 14.1 to 20.7% of the soil surface being wet by urine annually at stocking rates of 2.0 to 2.94 cows per hectare, consistent with previous research. These values may be used in conjunction with values for nitrate loss from urine and non-urine areas to calculate nitrate losses from grazed pasture at a range of stocking rates.
    • Use of Ochre from an Abandoned Metal Mine in the South East of Ireland for Phosphorus Sequestration from Dairy Dirty Water

      Fenton, Owen; Healy, Mark G.; Rodgers, M. (Soil Science Society of America, 2009-05)
      Ochre found at coal mine drainage sites in the United Kingdom shows a high phosphorus (P) retention capacity with little mobilization of metals. This indicates that ochre has the potential to adsorb P from agricultural wastewaters for possible use as a fertilizer. Little research has focused on the ability of metal mine ochre to sequester P in an environmentally sustainable way. Untreated acid mine drainage from an abandoned coppersulfur mine in the Avoca-Avonmore catchment in the south east of Ireland results in extensive low-value ochre deposition. In this study, P-amended water (50 mL) was mixed with this ochre (2.5 g) in batch experiments, and a maximum P adsorption capacity, calculated from the Langmuir equation, of between 16 and 21 g P kg−1 was calculated. However, mobilization of heavy metals from Avoca ochre in distilled, surface, and dirty water batch experiments was observed. This mobilization may inhibit ochre’s use in P removal from wastewaters.
    • The use of Sulphur as a Fertilizer

      Brogan, J.C.; Murphy, Matthew D. (An Foras Taluntais, 1979)
    • 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 BV, 2020-12)
      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.
    • Using machine learning to estimate herbage production and nutrient uptake on Irish dairy farms

      Nikoloski, Stevanche; Murphy, Philip; Kocev, Dragi; Džeroski, Sašo; Wall, David; Teagasc Walsh Fellowship Programme; European Union; 635201 (Elsevier for American Dairy Science Association, 2019-08-22)
      Nutrient management on grazed grasslands is of critical importance to maintain productivity levels, as grass is the cheapest feed for ruminants and underpins these meat and milk production systems. Many attempts have been made to model the relationships between controllable (crop and soil fertility management) and noncontrollable influencing factors (weather, soil drainage) and nutrient/productivity levels. However, to the best of our knowledge not much research has been performed on modeling the interconnections between the influencing factors on one hand and nutrient uptake/herbage production on the other hand, by using data-driven modeling techniques. Our paper proposes to use predictive clustering trees (PCT) learned for building models on data from dairy farms in the Republic of Ireland. The PCT models show good accuracy in estimating herbage production and nutrient uptake. They are also interpretable and are found to embody knowledge that is in accordance with existing theoretical understanding of the task at hand. Moreover, if we combine more PCT into an ensemble of PCT (random forest of PCT), we can achieve improved accuracy of the estimates. In practical terms, the number of grazings, which is related proportionally with soil drainage class, is one of the most important factors that moderates the herbage production potential and nutrient uptake. Furthermore, we found the nutrient (N, P, and K) uptake and herbage nutrient concentration to be conservative in fields that had medium yield potential (11 t of dry matter per hectare on average), whereas nutrient uptake was more variable and potentially limiting in fields that had higher and lower herbage production. Our models also show that phosphorus is the most limiting nutrient for herbage production across the fields on these Irish dairy farms, followed by nitrogen and potassium.
    • Using machine learning to estimate herbage production and nutrient uptake on Irish dairy farms

      Nikoloski, Stevanche; Murphy, Philip M.; Kocev, Dragi; Džeroski, Sašo; Wall, David; European Union; 635201 (Elsevier, 2019-08-22)
      Nutrient management on grazed grasslands is of critical importance to maintain productivity levels, as grass is the cheapest feed for ruminants and underpins these meat and milk production systems. Many attempts have been made to model the relationships between controllable (crop and soil fertility management) and noncontrollable influencing factors (weather, soil drainage) and nutrient/productivity levels. However, to the best of our knowledge not much research has been performed on modeling the interconnections between the influencing factors on one hand and nutrient uptake/herbage production on the other hand, by using data-driven modeling techniques. Our paper proposes to use predictive clustering trees (PCT) learned for building models on data from dairy farms in the Republic of Ireland. The PCT models show good accuracy in estimating herbage production and nutrient uptake. They are also interpretable and are found to embody knowledge that is in accordance with existing theoretical understanding of the task at hand. Moreover, if we combine more PCT into an ensemble of PCT (random forest of PCT), we can achieve improved accuracy of the estimates. In practical terms, the number of grazings, which is related proportionally with soil drainage class, is one of the most important factors that moderates the herbage production potential and nutrient uptake. Furthermore, we found the nutrient (N, P, and K) uptake and herbage nutrient concentration to be conservative in fields that had medium yield potential (11 t of dry matter per hectare on average), whereas nutrient uptake was more variable and potentially limiting in fields that had higher and lower herbage production. Our models also show that phosphorus is the most limiting nutrient for herbage production across the fields on these Irish dairy farms, followed by nitrogen and potassium.
    • Variations in travel time for N loading to groundwaters in four case studies in Ireland:Implications for policy makers and regulators

      Fenton, Owen; Coxon, Catherine E.; Haria, Atul H.; Horan, Brendan; Humphreys, James; Johnston, Paul; Murphy, Paul N. C.; Necpalova, Magdalena; Premrov, Alina; Richards, Karl G. (School of Agriculture, Food Science and Veterinary Medicine, University College Dublin in association with Teagasc, 2009)
      Mitigation measures to protect waterbodies must be implemented by 2012 to meet the requirements of the EU Water Framework Directive. The efficacy of these measures will be assessed in 2015. Whilst diffuse N pathways between source and receptor are generally long and complex, EU legislation does not account for differences in hydrological travel time distributions that may result in different water quality response times. The “lag time” between introducing mitigation measures and first improvements in water quality is likely to be different in different catchments; a process that should be considered by policy makers and catchment managers. Many examples of travel time variations have been quoted in the literature but no Irish specific examples are available. Lag times based on initial nutrient breakthrough at four contrasting sites were estimated to a receptor 500 m away from a source. Vertical travel times were estimated using a combination of depth of infiltration calculations based on effective rainfall and subsoil physical parameters and existing hydrological tracer data. Horizontal travel times were estimated using a combination of Darcian linear velocity calculations and existing tracer migration data. Total travel times, assuming no biogeochemical processes, ranged from months to decades between the contrasting sites; the shortest times occurred under thin soil/subsoil on karst limestone and the longest times through thick low permeability soils/subsoils over poorly productive aquifers. Policy makers should consider hydrological lag times when assessing the efficacy of mitigation measures introduced under the Water Framework Directive. This lag time reflects complete flushing of a particular nutrient from source to receptor. Further research is required to assess the potential mitigation of nitrate through denitrification along the pathway from source to receptor.
    • Visual drainage assessment: A standardised visual soil assessment method for use in land drainage design in Ireland

      Tuohy, Patrick; Humphreys, James; Holden, Nicholas M.; O'Loughlin, James; Reidy, Brian; Fenton, Owen (Teagasc (Agriculture and Food Development Authority), Ireland, 20/08/2016)
      The implementation of site-specific land drainage system designs is usually disregarded by landowners in favour of locally established ‘standard practice’ land drainage designs. This is due to a number of factors such as a limited understanding of soil–water interactions, lack of facilities for the measurement of soil’s physical or hydrological parameters and perceived time wastage and high costs. Hence there is a need for a site-specific drainage system design methodology that does not rely on inaccessible, time-consuming and/or expensive measurements of soil physical or hydrological properties. This requires a standardised process for deciphering the drainage characteristics of a given soil in the field. As an initial step, a new visual soil assessment method, referred to as visual drainage assessment (VDA), is presented whereby an approximation of the permeability of specific soil horizons is made using seven indicators (water seepage, pan layers, texture, porosity, consistence, stone content and root development) to provide a basis for the design of a site-specific drainage system. Across six poorly drained sites (1.3 ha to 2.6 ha in size) in south-west Ireland a VDA-based design was compared with (i) an ideal design (utilising soil physical measurements to elucidate soil hydraulic parameters) and (ii) a standard design (0.8 m deep drains at a 15 m spacing) by model estimate of water table control and rainfall recharge/drain discharge capacity. The VDA method, unlike standard design equivalents, provided a good approximation of an ideal (from measured hydrological properties) design and prescribed an equivalent land drainage system in the field. Mean modelled rainfall recharge/drain discharge capacity for the VDA (13.3 mm/day) and ideal (12.0 mm/day) designs were significantly higher (P < 0.001, s.e. 1.42 mm/day) than for the standard designs (0.5 mm/day), when assuming a design minimum water table depth of 0.45 m.
    • What Does Life-Cycle Assessment of agricultural products need for more meaningful inclusion of biodiversity?

      Teillard, Felix; Maia de Souza, Danielle; Thoma, Greg; Gerber, Pierre J.; Finn, John (Wiley, 05/06/2016)
      1.Decision-makers increasingly use life-cycle assessment (LCA) as a tool to measure the environmental sustainability of products. LCA is of particular importance in globalized agricultural supply chains, which have environmental effects in multiple and spatially dispersed locations. 2.Incorporation of impacts on biodiversity that arise from agricultural production systems into environmental assessment methods is an emerging area of work in LCA, and current approaches have limitations, including the need for (i) improved assessment of impacts to biodiversity associated with agricultural production, (ii) inclusion of new biodiversity indicators (e.g. conservation value, functional diversity, ecosystem services) and (iii) inclusion of previously unaccounted modelling variables that go beyond land-use impacts (e.g. climate change, water and soil quality). 3.Synthesis and applications. Ecological models and understanding can contribute to address the limitations of current life-cycle assessment (LCA) methods in agricultural production systems and to make them more ecologically relevant. This will be necessary to ensure that biodiversity is not neglected in decision-making that relies on LCA.
    • What does Life-Cycle Assessment of agricultural products need for more meaningful inclusion of biodiversity?

      Teillard, Félix; Maia de Souza, Danielle; Thoma, Greg; Gerber, Pierre J.; Finn, John A. (Wiley, 2016-06-05)
      Decision‐makers increasingly use life‐cycle assessment (LCA) as a tool to measure the environmental sustainability of products. LCA is of particular importance in globalized agricultural supply chains, which have environmental effects in multiple and spatially dispersed locations. Incorporation of impacts on biodiversity that arise from agricultural production systems into environmental assessment methods is an emerging area of work in LCA, and current approaches have limitations, including the need for (i) improved assessment of impacts to biodiversity associated with agricultural production, (ii) inclusion of new biodiversity indicators (e.g. conservation value, functional diversity, ecosystem services) and (iii) inclusion of previously unaccounted modelling variables that go beyond land‐use impacts (e.g. climate change, water and soil quality). Synthesis and applications. Ecological models and understanding can contribute to address the limitations of current life‐cycle assessment (LCA) methods in agricultural production systems and to make them more ecologically relevant. This will be necessary to ensure that biodiversity is not neglected in decision‐making that relies on LCA.
    • Yield of temperate forage grassland species is either largely resistant or resilient to experimental summer drought

      Hofer, Daniel; Suter, Matthias; Haughey, Eamon; Finn, John; Hoekstra, Nyncke J.; Buchmann, Nina; Luscher, A.; European Union; 266018 (Wiley, 17/06/2016)
      1.Due to climate change, an increasing frequency and severity of drought events are expected to impair grassland productivity, particularly of intensively managed temperate grasslands. 2.To assess drought impacts, a common field experiment to manipulate precipitation was set up at three sites (two Swiss and one Irish) using monocultures and mixtures with two and four key forage species. Species differed in their functional traits: a shallow-rooted non-legume (Lolium perenne L.), a deep-rooted non-legume (Cichorium intybus L.), a shallow-rooted legume (Trifolium repens L.) and a deep-rooted legume (Trifolium pratense L.). A 9-week summer drought was simulated, and soil water status, above-ground biomass yield and plant nitrogen (N) limitation were compared to a rainfed control. 3.Based on soil water measurements, the drought induced severe stress at both Swiss sites and extreme stress at the Irish site. Under severe stress, the legumes were more drought resistant and showed an average change in above-ground biomass (CAB, compared to rainfed control) of only −8% and −24% (for the two Swiss sites), while the non-legumes had an average CAB of −51% and −68%. The lower resistance of non-legumes coincided with an apparent limitation of plant N, which further increased under drought. Under extreme drought (Irish site), growth nearly ceased with an average CAB of −85%. 4.During a 6-week post-drought period with adequate water supply (Swiss sites), formerly drought-stressed species were highly resilient and either attained (legumes) or clearly outperformed (non-legumes) the yield level of the rainfed controls. This outperformance coincided with post-drought reductions in N limitation in formerly drought-stressed species. As a result, aggregated over the drought and the post-drought periods, a negative drought impact was found only for the shallow-rooted L. perenne at one of the severely stressed sites. 5.Significant overyielding by multispecies mixtures was evident under rainfed control conditions (+38% across all three sites, P < 0·05) and was equally apparent under severe drought (+50%, P < 0·05). This overyielding was greatest in mixtures with approximately equal species proportions and was sufficiently large that drought-stressed mixtures at least attained the same yield as the average of the rainfed monocultures. Under extreme drought, growth almost ceased in monocultures and mixtures. 6.Synthesis and applications. Yields of selected species of intensively managed temperate grasslands are either resistant to a single severe drought or are highly resilient as soon as soil moisture levels recover after the drought event. However, these forage species seem unable to cope with an extreme drought event. Combining species in mixtures can compensate for yield reductions caused by severe drought and it offers a practical management tool to adapt forage production to climate change.