• 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.
    • The effect of renovation of long-term temperate grassland on N2O emissions and N leaching from contrasting soils

      Krol, Dominika; Jones, M. B.; Williams, M.; Richards, Karl G.; Bourdin, F.; Lanigan, Gary; Department of Agriculture, Food and the Marine, Ireland; 07 RSF 527 (Elsevier, 19/04/2016)
      Renovation of long-term grassland is associated with a peak in soil organic N mineralisation which, coupled with diminished plant N uptake can lead to large gaseous and leaching N losses. This study reports on the effect of ploughing and subsequent N fertilisation on the N2O emissions and DON/NO3− leaching, and evaluates the impact of ploughing technique on the magnitude and profile of N losses. This study was carried out on isolated grassland lysimeters of three Irish soils representing contrasting drainage properties (well-drained Clonakilty, moderately-drained Elton and poorly-drained Rathangan). Lysimeters were manually ploughed simulating conventional (CT) and minimum tillage (MT) as two treatments. Renovation of grassland increased N2O flux to a maximum of 0.9 kg N2O–N ha− 1 from poorly-drained soil over four days after treatment. Although there was no difference between CT and MT in the post-ploughing period, the treatment influenced subsequent N2O after fertiliser applications. Fertilisation remained the major driver of N losses therefore reducing fertilisation rate post-planting to account for N mineralised through grassland renovation could reduce the losses in medium to longer term. Leaching was a significant loss pathway, with the cumulative drainage volume and N leached highly influenced by soil type. Overall, the total N losses (N2O + N leached) were lowest from poorly and moderately draining soil and highest for the well draining soil, reflecting the dominance of leaching on total N losses and the paramount importance of soil properties.
    • Effects of multi-species swards on dry matter production and the incidence of unsown species at three Irish sites

      Connolly, John; Finn, John; Black, Alistair D; Kirwan, Laura; Brophy, C.; Luscher, A.; European Union; Science Foundation Ireland; COST Action 852; 09/RFP/EOB2546 (Teagasc (Agriculture and Food Development Authority), Ireland, 2009)
      Recent ecological research provides evidence that an increased number of plant species in natural grasslands is associated with increased biomass productivity, and provides a wide range of other ecosystem benefits. This suggests that increases in species diversity in agricultural ecosystems may similarly lead to increased benefits. The work reported below was part of the COST 852 Agrodiversity experiment, carried out at 34 sites across Europe. In Ireland, the effects of four-species grass-clover mixtures on herbage production, species persistence and unsown species suppression at three sites over multiple years, were investigated under growing conditions that were intensive relative to unfertilised natural grassland systems. The design included a range of four-species mixtures and monocultures of perennial ryegrass, timothy, cocksfoot, white clover, red clover and Caucasian clover. Several harvests were taken at each site for two or three years. Species diversity had a strong, persistent and positive effect on overall yield and the yield of sown species, and enhanced resistance to the growth of unsown species. Mixtures generally yielded well when compared with the best monoculture, and sometimes out yielded it. These effects on total yield declined over time but were still important at the end of the experiments. The diversity effects on sown species yield and on resistance to unsown species increased with time. Diversity effects were robust to changes in species composition, and persisted for the duration of the experiments across mixtures and over time. Virtually every mixture had a higher yield, and suppressed unsown species better, than monocultures of perennial ryegrass. These patterns were broadly consistent across sites. The persistence of species varied widely and was not consistent across sites.
    • Effects of over-winter green cover on groundwater nitrate and dissolved organic carbon concentrations beneath tillage land

      Premrov, Alina; Coxon, Catherine E.; Hackett, Richard; Kirwan, Laura; Richards, Karl G. (Elsevier, 13/09/2012)
      Application of over-winter green cover (e.g. cover crops) as a measure for reducing nitrate losses from tillage land has been frequently investigated, especially in the unsaturated zone. Monitoring of groundwater is less common in these studies. Studies on groundwater responses to different land treatments can be challenging because they can be influenced by various conditions, such as recharge, seasonal variations, and aquifer properties, often occurring at different time scales than surface water processes. The aim of this study was to evaluate groundwater nitrate (NO3−single bondN) and dissolved organic carbon (DOC) concentration responses to different over-winter green covers: mustard, natural regeneration and no cover. A field experiment was designed and run for three years on tillage land underlain by a vulnerable sand and gravel aquifer in the south-east of Ireland. Results showed that over-winter green cover growth on tillage land can be an effective measure to reduce groundwater NO3−single bondN concentrations. A significant decrease in groundwater NO3−single bondN concentrations was observed under the mustard cover compared to no cover. All treatments, including no cover, showed a decline in groundwater NO3−single bondN concentrations over time. A significant increase in groundwater DOC was also observed under the mustard cover. Although the overall groundwater DOC concentrations were low, the increased DOC occurrence in groundwater should be accounted for in carbon balances and could potentially enhance groundwater denitrification in cases where aquifer conditions may favour it.
    • Effects of urease and nitrification inhibitors on yields and emissions in grassland and spring barley

      Forrestal, Patrick J.; Wall, David; Carolan, Rachael; Harty, Mary A.; Roche, Leanne; Krol, Dominika; Watson, C. J.; Lanigan, Gary; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; et al. (International Fertiliser Society, 09/12/2016)
      In trials conducted in the temperate maritime climate of Ireland on a range of acidic soils, calcium ammonium nitrate (CAN) and urea gave comparable yield performance. There was little evidence of reduced yields by using urea for grassland or spring barley. Our finding that urea produced annual yields that were not significantly different from CAN differs from previous studies which found that yields from urea were lower than those from ammonium nitrate or nitrate based fertiliser in the UK. However, there are also published results from trials conducted in temperate Irish grassland showing equal yield performance of CAN and urea in the 1970s. Based on yield performance and the cost of fertiliser there is scope to dramatically increase the level of urea usage in straight and blended fertilisers in the temperate maritime climate of Ireland in both grassland and spring barley. Such an increase will bring substantial benefits in terms of reducing direct nitrous oxide (N2O) emissions from fertiliser applied to soil, particularly in poorly draining soils subject to high levels of precipitation. Nitrogen recovery by plants tends to be more sensitive to differences in fertiliser efficiency than is yield. Although yields did not differ between urea and CAN; urea had a lower nitrogen recovery indicating that urea usage will also result in a reduced level of fertiliser use efficiency. Reduced efficiency is less tangible to farmers who tend to be primarily concerned with dependable yield results. Reduced efficiency is a problem nonetheless, particularly as it is closely linked to NH3 emissions in urea usage. European countries including Ireland have committed to reduce national NH3 emissions to comply with the revised National Emission Ceilings Directive (2001/81/EC) in Europe. Increased urea usage, which looks attractive from a yield, cost and direct N2O perspective in Ireland, runs counter to meeting these commitments. Additionally, NH3 is a source of indirect N2O emissions that will negate some of the N2O savings from urea. Due to the issues of yield dependability, fertiliser efficiency, N2O and NH3 emissions the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) is a particularly attractive option for making urea use more efficient by addressing its key weakness in the area of variable NH3 loss and efficiency. The urease inhibitor NBPT along with the nitrification inhibitor dicyandiamide (DCD) were tested with urea in comparison with calcium ammonium nitrate (CAN). The nitrification inhibitor DCD was very effective in reducing fertiliser N associated N2O emissions. Indeed, its usage allowed N2O levels to be reduced to levels comparable to where no application of N fertiliser was made at some site-years. However, at the DCD incorporation rate tested, DCD contributed to variability in NH3 loss from urea and suppressed both yield response and fertiliser efficiency. Use of the urease inhibitor NBPT in addition to DCD went a substantial way to resolving these shortcomings. Continuing work is needed to tailor the rate of existing and new urease and nitrification inhibitors to optimise the balance between suppression of gaseous N emissions, agronomic performance and economic considerations.
    • Efficacy of Woodchip Biochar and Brown Coal Waste as Stable Sorbents for Abatement of Bioavailable Cadmium, Lead and Zinc in Soil

      Amoah-Antwi, C.; Kwiatkowska-Malina, J.; Szara, E.; Thornton, S.; Fenton, Owen; Malina, G.; European Union; 675120 (Springer Science and Business Media LLC, 2020-10-03)
      Organic sorbents alter physicochemical soil properties and mitigate heavy metal (HM) bioavailability. However, some sorbents are labile and, therefore, introduce the risk of HM release into soil after mineralisation. Before field application, new stable organic sorbents such as woodchip biochar (BIO) and brown coal waste (BCW) need to be tested and compared with standard organic amendments like farmyard manure (FYM). An incubated pot experiment was conducted to investigate the efficacy of FYM, BIO and BCW (added to soil in pots at 5 and 10% w/w) to alter soil physicochemical properties and mitigate bioavailability of Cd, Pb and Zn spiked in treatments at different doses (in mg kg−1 ); 0 (not spiked), 1 (1 Cd, 70 Pb, 100 Zn) and 2 (3 Cd, 500 Pb, 700 Zn), and incubated for 9 weeks. At the end of the experiment, the EDTAextractable HM fractions, pH, cation exchange capacity (CEC) and specific surface area (SSA, to check trends) were determined in all treated soils. Results showed that FYM, BCW and BIO generally improved all soil properties (except reduced pH from BCW and apparent SSA reduction from FYM) and accounted for respective maximum abatements of Cd (50.2, 69.9 and 25.5%), Pb (34.2, 64.3 and 17.4%) and Zn (14.9, 17.7 and 11.8%) bioavailability in soil. FYM and BCW were more effective at 10% w/w especially in the low contaminated soil, whereas the highest efficacy for BIO was at 5% w/w and in the high contaminated soil. The efficacies of sorption by the organic sorbents varied for different HMs and were in the orders: BCW > FYM > BIO for Cd, FYM > BCW > BIO for Pb and BIO > BCW > FYM for Zn. Soil pH and CEC were strongly correlated with HM bioavailability in all treatments and implied that immobilisation of HMs occurred via complex formation, ion exchange and pH-dependent specific adsorption. All three sorbents were beneficial as soil amendments, and in terms of HM mitigation, BCW had the highest efficacy, followed by FYM and then BIO. Considering the documented high soil stability of BCW and BIO, these results are promising for further trialling at field scale.
    • The elusive role of soil quality in nutrient cycling: a review

      Schröder, J. J.; Schulte, R. P. O.; Creamer, R. E.; Delgado, A.; Leeuwen, J.; Lehtinen, T.; Rutgers, M.; Spiegel, H.; Staes, J.; Tóth, G.; et al. (Wiley, 2016-09-16)
      Cycling of nutrients, including nitrogen and phosphorus, is one of the ecosystem services we expect agricultural soils to deliver. Nutrient cycling incorporates the reuse of agricultural, industrial and municipal organic residues that, misleadingly, are often referred to as ‘wastes’. The present review disentangles the processes underlying the cycling of nutrients to better understand which soil properties determine the performance of that function. Four processes are identified (i) the capacity to receive nutrients, (ii) the capacity to make and keep nutrients available to crops, (iii) the capacity to support the uptake of nutrients by crops and (iv) the capacity to support their successful removal in harvested crop. Soil properties matter but it is imperative that, as constituents of ‘soil quality’, they should be evaluated in the context of management options and climate and not as ends in their own right. The effect of a soil property may vary depending on the prevailing climatic and hydrologic conditions and on other soil properties. We recognize that individual soil properties may be enhancing one of the processes underlying the cycling of nutrients but simultaneously weakening others. Competing demands on soil properties are even more obvious when considering other soil functions such as primary production, purification and flow regulation of water, climate modification and habitat provision, as shown by examples. Consequently, evaluations of soil properties and management actions need to be site-specific, taking account of local aspects of their suitability and potential challenges.
    • Enteropathogen survival in soil from different land-uses is predominantly regulated by microbial community composition

      Moynihan, Emma; Richards, Karl G.; Brennan, Fiona P.; Tyrrel, Sean; Ritz, Karl; Teagasc Post-doctoral Fellowship Scheme; Teagasc Walsh Fellowship Programme (Elsevier, 23/01/2015)
      Microbial enteropathogens can enter the environment via landspreading of animal slurries and manures. Biotic interactions with the soil microbial community can contribute to their subsequent decay. This study aimed to determine the relative impact of biotic, specifically microbial community structure, and physico-chemical properties associated with soils derived from 12 contrasting land-uses on enteropathogen survival. Phenotypic profiles of microbial communities (via phospholipid fatty acid (PLFA) profiling), and total biomass (by fumigation-extraction), in the soils were determined, as well as a range of physicochemical properties. The persistence of Salmonella Dublin, Listeria monocytogenes, and Escherichia coli was measured over 110 days within soil microcosms. Physicochemical and biotic data were used in stepwise regression analysis to determine the predominant factor related to pathogen-specific death rates. Phenotypic structure, associated with a diverse range of constituent PLFAs, was identified as the most significant factor in pathogen decay for S. Dublin, L. monocytogenes, non-toxigenic E. coli O157 but not for environmentally-persistent E. coli. This demonstrates the importance of entire community-scale interactions in pathogen suppression, and that such interactions are context-specific.
    • Environmental aspects of soil phosphorus testing

      Daly, Karen M.; Casey, A. (Teagasc (Agriculture and Food Development Authority), Ireland, 2005)
      Soil phosphorus testing in Ireland uses Morgan’s reagent from samples taken to 10 cm depth for agronomic recommendations. However, its suitability as an environmental indicator has been questioned in terms of sample depth and extraction solution. Seven grassland sites were sampled to depths of 2, 5 and 10 cm and extracted for Morgan’s P, the standard agronomic test, as well as iron-oxide impregnated paper strip P (FeOP), calcium chloride extractable P (CaCl2-P) and water soluble P (WSP), all proposed as environmental soil tests. Extractable soil P decreased with increasing sample depth, as did variances in each test, such that, 2 cm samples had highest concentrations and variances. The current standard sample depth (10 cm) was linearly related to corresponding data from samples taken to 2 and 5 cm, indicating that surface soil P can be consistently estimated from the current standard depth. When soil tests were compared with dissolved reactive P (DRP) in overland flow collected from two field sites, certain soil tests were better indicators of P loss than others. The relative difference in Morgan’s P values at the standard sample depth (10 cm) was reflected in the relative difference in P loss between the two sites. Average values of DRP collected from two sites ranged from 0.032 to 0.067 mg/l at the low P site and 0.261 to 0.620 at the high P site. Average DRP values from the high P site and maximum DRP values from the low P site were simulated using water-soluble P extraction at water to soil ratios 5 to 250 l/kg. In this study, Morgan’s P to 10 cm gave a good indication of the relative difference in DRP loss between the two sites.
    • Environmental footprint family to address local to planetary sustainability and deliver on the SDGs

      Vanham, Davy; Leip, Adrian; Galli, Alessandro; Kastner, Thomas; Bruckner, Martin; Uwizeye, Aimable; van Dijk, Kimo; Ercin, Ertug; Dalin, Carole; Brandão, Miguel; et al. (Elsevier BV, 2019-07-29)
      The number of publications on environmental footprint indicators has been growing rapidly, but with limited efforts to integrate different footprints into a coherent framework. Such integration is important for comprehensive understanding of environmental issues, policy formulation and assessment of trade-offs between different environmental concerns. Here, we systematize published footprint studies and define a family of footprints that can be used for the assessment of environmental sustainability. We identify overlaps between different footprints and analyse how they relate to the nine planetary boundaries and visualize the crucial information they provide for local and planetary sustainability. In addition, we assess how the footprint family delivers on measuring progress towards Sustainable Development Goals (SDGs), considering its ability to quantify environmental pressures along the supply chain and relating them to the water-energy-food-ecosystem (WEFE) nexus and ecosystem services. We argue that the footprint family is a flexible framework where particular members can be included or excluded according to the context or area of concern. Our paper is based upon a recent workshop bringing together global leading experts on existing environmental footprint indicators.
    • Essential elements and heavy metal concentrations in a small area of the Castlecomer Plateau, Co. Kilkenny, Ireland: Implications for animal performance.

      Canty, M.J.; McCormack, Stephen; Lane, E.A.; Collins, D.M.; More, Simon J (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      Many ruminants are solely or mostly dependant for their nutrients, including essential elements, on the forage available to them, either in its natural state or conserved as hay or silage. A soil and herbage survey was carried out in April and September 2007, in a 3.1 km × 3.0 km grid, incorporating 106 and 46 sampling points, respectively, on the Castlecomer Plateau, Co. Kilkenny, Ireland. The aim was to determine the nutrient and heavy metal status of soil and herbage in the sampling area, and to examine the concentrations observed for their potential to impact on animal performance. Low soil pH and high soil lime requirements were identified within the sampling area. The concentrations of Ca, Cu, Se and Zn were low in both soil and herbage. These conditions are similar to those found on other farms in Ireland. Fluoride was detected in 61 of the 97 herbage samples in April 2007, but only four exceeded 40 mg/kg dry matter, the maximum tolerable level for cattle. Mineral imbalances (Ca, Cu, Se and Zn) observed in pastures caused by low soil mineral status, exacerbated by low soil pH, could impair animal performance in the area studied.
    • Evaluating E. coli Transport Risk in Soil using Dye and Bromide Tracers

      Brennan, Fiona P.; Kramers, Gaelene; Grant, Jim; O'Flaherty, Vincent; Holden, Nicholas M.; Richards, Karl G.; Irish Research Council for Science, Engineering and Technology (Soil Science Society of America, 2012-03)
      Dye and bromide tracers are established methods of assessing the presence, function, and extent of hydrological pathways in soil. Prediction of E. coli transport pathways in soil, using brilliant blue (BB) dye and bromide tracers, was investigated using in situ field trials on three grassland soil types, under different moisture regimes. Passive transport through preferential flow routes was the dominant mechanism of vertical E. coli transport in the soils studied. However, lateral movement of E. coli from macropores to the soil matrix was also observed. E. coli transport was mainly associated with visualized infiltration patterns but there was some evidence of differential transport of BB and E. coli. Maximum E. coli depth was found not to co-occur with BB and bromide tracers in 44 and 71% of samples, respectively. Soil type and season of application were important in the distribution and maximum depth of E. coli, and the relationship between the bacterium and its tracers. Moisture content was found to be important for the relationship between E. coli and BB, and the extent of this effect varied with soil type. There was a trend of increasing E. coli concentrations to a peak sample moisture concentration of 0.3 to 0.4 g g−1 dry soil followed by a decrease. Overall BB was found to have greater predictive value than Br. Correlation and co-occurrence analysis found that shortly after land application both BB and Br were good predictors of E. coli transport pathways and distribution under certain conditions, but underestimate risk to shallow groundwater.
    • Evaluation of Amendments to Control Phosphorus Losses in Runoff from Dairy-Soiled Water

      Fenton, Owen; Serrenho, Ana; Healy, Mark G.; Department of Agriculture, Food and the Marine, Ireland; RSF 07 525 (Springer, 2011-11)
      Amendments with the potential to reduce phosphorus (P) losses from agricultural grassland arising from the land application of dairy-soiled water (DSW) were investigated. Optimal application rates were studied, and associated costs and feasibility were estimated. First, batch tests were carried out to identify appropriate chemicals or phosphorus sorbing materials to control P in runoff from DSW. Then, the best four treatments were examined in an agitator test. In this test, soil—placed in a beaker—was loaded with DSW or amended DSW at a rate equivalent to 5 mm ha−1 (the maximum permissible application rate of DSW allowable in a 42-day period in Ireland). The soil was overlain with continuously stirred water to simulate runoff on land-applied DSW. Optimum application rates were selected based on percentage removal of dissolved reactive phosphorus in overlying water and the estimated cost of amendment. The costs of the amendments, per cubic metre of DSW, increased in the order: bottom ash (1.55 €), alum (1.67 to 1.92 €), FeCl2·4H2O (3.55 to 8.15 €), and lime (20.31 to 88.65 €). The feasibility of the amendments, taking into account their cost, potential adverse effects, public perception, and their performance, decreased in the order: alum > FeCl2·4H2O > bottom ash > lime. Amendments to DSW could be introduced in critical source areas—areas where high soil test P and direct migration pathways to a receptor overlap.
    • Evaluation of Amendments to Control Phosphorus Losses in Runoff from Pig Slurry Applications to Land

      O'Flynn, Cornelius J.; Fenton, Owen; Healy, Mark G.; Irish Research Council (WILEY-VCH Verlag GmbH, 24/11/2011)
      If spread in excess of crop requirements, incidental phosphorus (P) losses from agriculture can lead to eutrophication of receiving waters. The use of amendments in targeted areas may help reduce the possibility of surface runoff of nutrients. The aim of this study was to identify amendments which may be effective in reducing incidental dissolved reactive phosphorus (DRP) losses in surface runoff from land applied pig slurry. For this purpose, the DRP losses under simulated conditions across the surface of intact grassland soil cores, loaded with unamended and amended slurry at a rate equivalent to 19 kg P ha−1, were determined over a 30 h period. The effectiveness of the amendments at reducing DRP in overlying water were (in decreasing order): alum (86%), flue gas desulfurization by-product (FGD) (74%), poly-aluminum (Al) chloride (PAC) (73%), ferric chloride (71%), fly ash (58%), and lime (54%). FGD was the most costly of all the treatments (€7.64/m3 for 74% removal). Ranked in terms of feasibility, which takes into account effectiveness, cost, and other potential impediments to use, they were: alum, ferric chloride, PAC, fly ash, lime, and FGD.
    • Evaluation of chemical amendments to control phosphorus losses from dairy slurry

      Brennan, Raymond B.; Fenton, Owen; Rodgers, M.; Healy, Mark G. (Wiley; British Society of Soil Science, 14/04/2011)
      Land application of dairy slurry can result in incidental losses of phosphorus (P) to runoff in addition to increased loss of P from soil as a result of a buildup in soil test P (STP). An agitator test was used to identify the most effective amendments to reduce dissolved reactive phosphorus (DRP) loss from the soil surface after land application of chemically amended dairy cattle slurry. This test involved adding slurry mixed with various amendments (mixed in a beaker using a jar test flocculator at 100 rpm), to intact soil samples at approximate field capacity. Slurry/amended slurry was applied with a spatula, submerged with overlying water and then mixed to simulate overland flow. In order of effectiveness, at optimum application rates, ferric chloride (FeCl2) reduced the DRP in overlying water by 88%, aluminium chloride (AlCl2) by 87%, alum (Al2(SO4)3·nH2O) by 83%, lime by 81%, aluminium water treatment residuals (Al-WTR; sieved to <2 mm) by 77%, flyash by 72%, flue gas desulphurization by-product by 72% and Al-WTR sludge by 71%. Ferric chloride (€4.82/m3 treated slurry) was the most cost-effective chemical amendment. However, Al compounds are preferred owing to stability of Al–P compared with Fe–P bonds. Alum is less expensive than AlCl2 (€6.67/m3), but the risk of effervescence needs further investigation at field-scale. Phosphorus sorbing materials (PSM) were not as efficient as chemicals in reducing DRP in overlying water. The amendments all reduced P loss from dairy slurry, but the feasibility of these amendments may be limited because of the cost of treatment.
    • Evaluation of headspace equilibration methods for quantifying greenhouse gases in groundwater

      Jahangir, Mohammad M. R.; Johnston, Paul; Khalil, Mohammed I.; Grant, Jim; Somers, Cathal; Richards, Karl G.; Department of Agriculture, Food and the Marine, Ireland; Department of Civil, Structural and Environmental Engineering, Trinity College Dublin; RSF 06383 (Elsevier, 23/08/2012)
      The objective of the study was to evaluate the different headspace equilibration methods for the quantification of dissolved greenhouse gases in groundwater. Groundwater samples were collected from wells with contrasting hydrogeochemical properties and degassed using the headspace equilibration method. One hundred samples from each well were randomly selected, treatments were applied and headspace gases analysed by gas chromatography. Headspace equilibration treatments varied helium (He):water ratio, shaking time and standing time. Mean groundwater N2O, CO2 and CH4 concentrations were 0.024 mg N L−1, 13.71 mg C L−1 and 1.63 μg C L−1, respectively. All treatments were found to significantly influence dissolved gas concentrations. Considerable differences in the optimal He:water ratio and standing time were observed between the three gases. For N2O, CO2 and CH4 the optimum operating points for He:water ratio was 4.4:1, 3:1 and 3.4:1; shaking time was 13, 12 and 13 min; and standing time was 63, 17 and 108 min, respectively. The headspace equilibration method needs to be harmonised to ensure comparability between studies. The experiment reveals that He:water ratio 3:1 and shaking time 13 min give better estimation of dissolved gases than any lower or higher ratios and shaking times. The standing time 63, 17 and 108 min should be applied for N2O, CO2 and CH4, respectively.
    • Evaluation of Mehlich 3 as a Micronutrient Extractant on Irish Grassland Soils

      Brennan, Denis D. (2002)
      The use of multinutrient extractants has been increasing in recent years, Mehlich 3 (M3) being one that has gained wide acceptance. The objective of this study was to see how M3 compared with methods currently used in Ireland for Cu, Zn, Mn and Fe extraction, and to investigate if it could be used to determine available Mo. Samples from eight mineral soil types, four of sandstone/shale and four of limestone origin and some organic soils were analysed for the micronutrients Cu, Fe, Mn, Mo and Zn using M3 and conventional extractants. Herbage samples were taken from specific mineral soils and analysed for the same range of elements. M3 results showed good correlation with EDTA and DTPA extractable Cu and Zn, and with easily reducible Mn, but poor correlation with DTPA extractable Mn and Fe. It was not possible to measure Mo in the M3 extract. Inclusion of soil properties and interacting elements in multiple regression models improved the coefficients of determination. Different relationships between extractants were displayed for mineral and organic soils. All extractants were equal in their ability to predict micronutrient content of herbage. Differences between sandstone/shale and limestone soils in relation to herbage micronutrient content were also found; the better relationships were generally found on the sandstone/shale. Results are generally in line with published data, but disagree with those of some studies. M3 is subject to the same shortcomings as existing extractants, but it’s versatility and range does offer an advantage.
    • An evaluation of urine patch simulation methods for nitrous oxide emission measurement

      Forrestal, Patrick J.; Krol, Dominika; Lanigan, Gary; Jahangir, Mohammad M. R.; Richards, Karl G. (Cambridge University Press, 28/11/2016)
      Global nitrous oxide (N2O) inventory estimates for pasture systems are refined based on measurements of N2O loss from simulated urine patches. A variety of methods are used for patch simulation but they frequently use a uniform wetted area (UWA), often smaller than a bovine urine patch. However, natural patches follow non-uniform infiltration patterns expanding naturally from a point of deposit with a non-wetted zone of influence. Using 2 litres of urine the UWA method was compared, using a 0·156 m2 collar, with a naturally expanding effective area (NEEA) method, using a 0·462 m2 collar under high (HL) and low (LL) N2O loss conditions. The method chosen affects urine nitrogen (N) loading to the soil. Under HL the UWA method induced a N2O-N loss of 280·6 mg/patch, significantly less than the 434·8 mg/patch loss for the NEEA method, for the same simulated urination. Under LL there was no method effect. Efforts should be made to employ patch simulation methods, which mimic natural deposits and can be achieved, at least in part, by: (a) Using a urine volume and N content similar to that of the animal of interest. (b) Allowing natural infiltration of the chosen urine volume to permit tapering towards the edges. (c) Measuring from the zone of influence in addition to the wetted area, i.e. the patch effective area.
    • Exploring Climate‐Smart Land Management for Atlantic Europe

      Schulte, Rogier P. O.; O'Sullivan, Lilian; Coyle, Cait; Farrelly, Niall; Gutzler, Carsten; Lanigan, Gary; Torres‐Sallan, Gemma; Creamer, Rachel E.; Dairy Research Trust; Department of Agriculture, Food and the Marine (Wiley, 2016-09)
      Core Ideas Managing soil organic carbon is an essential aspect of climate‐smart agriculture. Combining component research, we derive a soil carbon management concept for Ireland. Optimized soil carbon management is differentiated in accordance with soil type. Existing policy tools can be tailored to incentivize climate‐smart land management. Soils can be a sink or source of carbon, and managing soil carbon has significant potential to partially offset agricultural greenhouse gas emissions. While European Union (EU) member states have not been permitted to account for this offsetting potential in their efforts to meet the EU 2020 reduction targets, this policy is now changing for the period 2020 to 2030, creating a demand for land management plans aimed at maximizing the offsetting potential of land. In this letter, we derive a framework for climate‐smart land management in the Atlantic climate zone of the EU by combining the results from five component research studies on various aspects of the carbon cycle. We show that the options for proactive management of soil organic carbon differ according to soil type and that a spatially tailored approach to land management will be more effective than blanket policies.