• A comparison of SWAT, HSPF and SHETRAN/GOPC for modelling phosphorus export from three catchments in Ireland

      Nasr, Ahmed Elssidig; Bruen, Michael; Jordan, Philip; Moles, Richard; Kiely, Gerard; Byrne, Paul (Elsevier, 2012-07-02)
      Recent extensive water quality surveys in Ireland revealed that diffuse phosphorus (P) pollution originating from agricultural land and transported by runoff and subsurface flows is the primary cause of the deterioration of surface water quality. P transport from land to water can be described by mathematical models that vary in modelling approach, complexity and scale (plot, field and catchment). Here, three mathematical models (SWAT, HSPF and SHETRAN/GOPC) of diffuse P pollution have been tested in three Irish catchments to explore their suitability in Irish conditions for future use in implementing the European Water Framework Directive. After calibrating the models, their daily flows and total phosphorus (TP) exports are compared and assessed. The HSPF model was the best at simulating the mean daily discharge while SWAT gave the best calibration results for daily TP loads. Annual TP exports for the three models and for two empirical models were compared with measured data. No single model is consistently better in estimating the annual TP export for all three catchments.
    • Agriculture, meteorology and water quality in Ireland: a regional evaluation of pressures and pathways of nutrient loss to water

      Schulte, Rogier P.; Richards, Karl G.; Daly, Karen M.; Kurz, I.; McDonald, E.J.; Holden, N.M. (Royal Irish Academy, 2006-07-31)
      The main environmental impact of Irish agriculture on surface and ground water quality is the potential transfer of nutrients to water. Soil water dynamics mediate the transport of nutrients to water, and these dynamics in turn depend on agro-meteorological conditions, which show large variations between regions, seasons and years. In this paper we quantify and map the spatio-temporal variability of agro-meteorological factors that control nutrient pressures and pathways of nutrient loss. Subsequently, we evaluate their impact on the water quality of Irish rivers. For nitrogen, pressure and pathways factors coincide in eastern and southern areas, which is reflected in higher nitrate levels of the rivers in these regions. For phosphorus, pathway factors are most pronounced in north-western parts of the country. In south-eastern parts, high pressure factors result in reduced biological water quality. These regional differences require that farm practices be customised to reflect the local risk of nutrient loss to water. Where pathways for phosphorus loss are present almost year-round—as is the case in most of the north-western part of the country—build-up of pressures should be prevented, or ameliorated where already high. In south-eastern areas, spatio-temporal coincidence of nutrient pressures and pathways should be prevented, which poses challenges to grassland management.
    • Chemical amendment of pig slurry: control of runoff related risks due to episodic rainfall events up to 48 h after application

      O'Flynn, Cornelius J.; Healy, Mark G.; Wilson, Paul; Hoekstra, Nyncke J.; Troy, Shane M.; Fenton, Owen (Springer, 2013-09-01)
      Losses of phosphorus (P) from soil and slurry during episodic rainfall events can contribute to eutrophication of surface water. However, chemical amendments have the potential to decrease P and suspended solids (SS) losses from land application of slurry. Current legislation attempts to avoid losses to a water body by prohibiting slurry spreading when heavy rainfall is forecast within 48 h. Therefore, in some climatic regions, slurry spreading opportunities may be limited. The current study examined the impact of three time intervals (TIs; 12, 24 and 48 h) between pig slurry application and simulated rainfall with an intensity of 11.0±0.59 mm h-1. Intact grassed soil samples, 1 m long, 0.225 m wide and 0.05 m deep, were placed in runoff boxes and pig slurry or amended pig slurry was applied to the soil surface. The amendments examined were: (1) commercial-grade liquid alum (8% Al2O3) applied at a rate of 0.88:1 [Al/total phosphorus (TP)] (2) commercial-grade liquid ferric chloride (38% FeCl3) applied at a rate of 0.89:1 [Fe/TP] and (3) commercial-grade liquid poly-aluminium chloride (10 % Al2O3) applied at a rate of 0.72:1 [Al/TP]. Results showed that an increased TI between slurry application and rainfall led to decreased P and SS losses in runoff, confirming that the prohibition of land-spreading slurry if heavy rain is forecast in the next 48 h is justified. Averaged over the three TIs, the addition of amendment reduced all types of P losses to concentrations significantly different (p<0.05) to those from unamended slurry, with no significant difference between treatments. Losses from amended slurry with a TI of 12 h were less than from unamended slurry with a TI of 48 h, indicating that chemical amendment of slurry may be more effective at ameliorating P loss in runoff than current TI-based legislation. Due to the high cost of amendments, their incorporation into existing management practices can only be justified on a targeted basis where inherent soil characteristics deem their usage suitable to receive amended slurry.
    • Developing the EU Farm Accountancy Data Network to derive indicators around the sustainable use of nitrogen and phosphorus at farm level.

      Buckley, Cathal; Wall, David P; Moran, Brian; Murphy, Paul N.C.; Department of Agriculture, Food and the Marine (Springer, 2015-07)
      This study uses a national farm survey which is part of the European Union (EU) Farm Accountancy Data Network (FADN) to develop environmental sustainability indicators in the use of nitrogen (N) and phosphorus (P) across a range of farm systems in the Republic of Ireland. Farm level micro data were used to calculate all inputs and outputs of N and P that cross the farm gate and to derive balances (kg ha-1) and overall use efficiencies across 827 farms in 2012. The sample is populated weighted to represents 71,480 farms nationally. Results indicated an average N balance of 71.0 kg ha-1 and use efficiency of 36.7% across the nationally representative sample. Nitrogen balances were between two and four times higher across specialist dairy farms compared to livestock rearing and specialist tillage systems. Nitrogen use efficiency was generally lowest across milk producing systems compared to livestock rearing and tillage systems. Phosphorus balance and use efficiency averaged 4.7 kg ha-1 and 79.6% respectively across the sample. Specialist tillage and dairying farms had higher average P balances compared to other livestock based systems. The approach developed in this analysis will form the benchmark for temporal analysis across these indicators for future nutrient balance and efficiency trends and could assist other members of the EU FADN to develop similar nationally representative indicators.
    • Effect of phosphorus level and phytase inclusion on the performance, bone mineral concentration, apparent nutrient digestibility, and on mineral and nitrogen utilisation in finisher pigs.

      Varley, T.F.; Callan, J.J.; O'Doherty, J.V. (Teagasc, Oak Park, Carlow, Ireland, 2010)
      Two experiments were conducted to investigate the interaction between dietary P concentration and phytase (PHY) inclusion in the diet of finisher pigs. In Experiment 1, the growth performance and bone analysis experiment, pigs (6 replicate groups of 14 pigs each per treatment; initial body weight (BW) = 45.2 kg) were allocated to one of six dietary treatments (for 74 days) in a 3 × 2 factorial arrangement: T1 – available P in the diet = 1.5 g/kg; T2 = T1 with 500 units of phytase (FTU)/kg; T3 – available P = 2.0 g/kg; T4 = T3 with 500 FTU/kg; T5 – available P = 2.5 g/kg; T6 = T5 with 500 FTU/kg. Experiment 2 consisted of a digestibility and a P, Ca and N balance study, and pigs (6 per treatment; initial BW = 67.3 kg) were offered identical diets to those offered in Experiment 1. There was an interaction between dietary P level and PHY inclusion for average daily gain (ADG) and carcass weight (CW; P < 0.05) in Experiment 1. Pigs offered the low P diet supplemented with PHY had a higher ADG and CW than pigs offered the non-PHY, low P diet. However, there was no effect (P > 0.05) of PHY inclusion on ADG or CW with the medium or high P diets. Higher concentrations of ash, P and Ca in bone were noted in pigs offered the medium and high P diets (P < 0.001) and PHY (P < 0.01) diets when compared to pigs offered the low P without PHY. Pigs offered diets supplemented with PHY had lower faecal P output (P < 0.01) and a higher P digestibility (P < 0.001) and P retention (P < 0.05) than pigs offered diets without added PHY. In conclusion, supplementation of a low-P finisher diet with PHY resulted in pigs that had a similar carcass weight, but weaker bones than pigs offered a medium or high P diet.
    • 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.
    • Farm-gate N and P balances and use efficiencies across specialist dairy farms in the Republic Ireland

      Buckley, Cathal; Murphy, Paul; Wall, David (Teagasc, Oak Park, Carlow, Ireland, 2013)
      This study establishes farm gate N and P balances and use efficiencies based on the average of 2 years of Teagasc National Farm Survey data in 2009 and 2010. The weighted average farm gate N surplus for this nationally representative sample of specialist dairy farms was 143.4 kg N ha-1. Average farm gate nitrogen use efficiency was 23.2%. For dairy farms operating under an EU Nitrates Derogation, the average N surplus was higher at 181.8 kg N ha-1 and averageN use efficiency was slightly lower at 22.2%. The total average farm gate P balance was 4.1 kg ha-1 in surplus, and P use efficiency averaged 83.9%. P balance ranged from -7.3 to 23.0 kg ha-1. A total of 27% had a negative P balance. The average P surplus for farms with a Nitrates Derogation was below the average of all farms at 3.5 kg P ha-1 and average P use efficiency for these Derogation farms was above the average of all farms at 90%.
    • Impact of pig slurry amendments on phosphorus, suspended sediment and metal losses in laboratory runoff boxes under simulated rainfall

      O'Flynn, Cornelius J.; Fenton, Owen; Wilson, P.; Healy, Mark G. (Elsevier, 2012-12-30)
      Losses of phosphorus (P) when pig slurry applications to land are followed by a rainfall event or losses from soils with high P contents can contribute to eutrophication of receiving waters. The addition of amendments to pig slurry spread on high P Index soils may reduce P and suspended sediment (SS) losses. This hypothesis was tested at laboratory-scale using runoff boxes under simulated rainfall conditions. Intact grassed soil samples, 100 cm-long, 22.5 cm-wide and 5 cm-deep, were placed in runoff boxes and pig slurry or amended pig slurry was applied to the soil surface. The amendments examined were: (1) commercial grade liquid alum (8% Al2O3) applied at a rate of 0.88:1 [Al:total phosphorus (TP)] (2) commercial-grade liquid ferric chloride (38% FeCl3) applied at a rate of 0.89:1 [Fe:TP] and (3) commercial-grade liquid poly-aluminium chloride (PAC) (10% Al2O3) applied at a rate of 0.72:1 [Al:TP]. The grassed soil was then subjected to three rainfall events (10.3 ± 0.15 mm h−1) at time intervals of 48, 72, and 96 h following slurry application. Each sod received rainfall on 3 occasions. Results across three rainfall events showed that for the control treatment, the average flow weighted mean concentration (FWMC) of TP was 0.61 mg L−1, of which 31% was particulate phosphorus (PP), and the average FWMC of SS was 38.1 mg L−1. For the slurry treatment, there was an average FWMC of 2.2 mg TP L−1, 47% of which was PP, and the average FWMC of SS was 71.5 mg L−1. Ranked in order of effectiveness from best to worst, PAC reduced the average FWMC of TP to 0.64 mg L−1 (42% PP), FeCl3 reduced TP to 0.91 mg L−1 (52% PP) and alum reduced TP to 1.08 mg L−1 (56% PP). The amendments were in the same order when ranked for effectiveness at reducing SS: PAC (74%), FeCl3 (66%) and alum (39%). Total phosphorus levels in runoff plots receiving amended slurry remained above those from soil only, indicating that, although incidental losses could be mitigated by chemical amendment, chronic losses from the high P index soil in the current study could not be reduced.
    • Impact of pig slurry amendments on phosphorus, suspended sediment and metal losses in laboratory runoff boxes under simulated rainfall

      O'Flynn, Cornelius J.; Fenton, Owen; Wilson, P.; Healy, Mark G. (Elsevier, 2012-12-30)
      Losses of phosphorus (P) when pig slurry applications to land are followed by a rainfall event or losses from soils with high P contents can contribute to eutrophication of receiving waters. The addition of amendments to pig slurry spread on high P Index soils may reduce P and suspended sediment (SS) losses. This hypothesis was tested at laboratory-scale using runoff boxes under simulated rainfall conditions. Intact grassed soil samples, 100 cm-long, 22.5 cm-wide and 5 cm-deep, were placed in runoff boxes and pig slurry or amended pig slurry was applied to the soil surface. The amendments examined were: (1) commercial grade liquid alum (8% Al2O3) applied at a rate of 0.88:1 [Al:total phosphorus (TP)] (2) commercial-grade liquid ferric chloride (38% FeCl3) applied at a rate of 0.89:1 [Fe:TP] and (3) commercial-grade liquid poly-aluminium chloride (PAC) (10% Al2O3) applied at a rate of 0.72:1 [Al:TP]. The grassed soil was then subjected to three rainfall events (10.3 ± 0.15 mm h−1) at time intervals of 48, 72, and 96 h following slurry application. Each sod received rainfall on 3 occasions. Results across three rainfall events showed that for the control treatment, the average flow weighted mean concentration (FWMC) of TP was 0.61 mg L−1, of which 31% was particulate phosphorus (PP), and the average FWMC of SS was 38.1 mg L−1. For the slurry treatment, there was an average FWMC of 2.2 mg TP L−1, 47% of which was PP, and the average FWMC of SS was 71.5 mg L−1. Ranked in order of effectiveness from best to worst, PAC reduced the average FWMC of TP to 0.64 mg L−1 (42% PP), FeCl3 reduced TP to 0.91 mg L−1 (52% PP) and alum reduced TP to 1.08 mg L−1 (56% PP). The amendments were in the same order when ranked for effectiveness at reducing SS: PAC (74%), FeCl3 (66%) and alum (39%). Total phosphorus levels in runoff plots receiving amended slurry remained above those from soil only, indicating that, although incidental losses could be mitigated by chemical amendment, chronic losses from the high P index soil in the current study could not be reduced.
    • Modelling Phosphorus for Grassland: Agronomically and Environmentally Sustainable Advice

      Schulte, Rogier P. (Teagasc, 2006-01-01)
      In 2006, the Nitrates Directive (through S.I. 378 (Anon, 2006)) was implemented in Ireland, aimed at reducing nutrient losses from agriculture to water bodies, i.e. surface waters, groundwater and estuarine waters. This legislation introduced strict regulation of nutrient management on Irish farms. Thus far, nutrient management had largely been based on Teagasc advice (Coulter, 2004). However, in the new policy climate, in addition to advice, compliance with legal limits is also required. This significant change in the practicalities surrounding nutrient management led to a review of Teagasc nutrient (phosphorus and nitrogen) advice, based on the following considerations: Traditionally, nutrient advice had largely been based on fertiliser rates for economically optimal productivity, i.e. rates at which further fertiliser applications would not result in higher economic returns. Now, SI 378 of 2006 demands that nutrient application rates do not exceed crop (grass) demand, nor result in nutrient losses that may have a negative impact on water quality. Previous phosphorus (P) advice (Coulter, 2004) was similar for all soil types, and did not account for potentially different P-requirements, or indeed potentially different risks of P-loss to water between soils. Previous P advice was based on returning optimum crop yields. However, grassland management in Ireland is increasingly focussed on maximising the amount of herbage grazed in situ. With extended grazing seasons and an increasing share of the animal diet consisting of grazed herbage, the scope and flexibility of diet supplementation through straights and concentrates is reduced. An increasing proportion of dietary P must be obtained from this grazed herbage as a result. Therefore P fertiliser strategies should no longer be based on yield responses alone, but in addition sustain adequate herbage P-concentrations in order to ensure that the dietary P requirements can be met on a non-supplemented diet of grazed herbage. Against this background, Teagasc, Johnstown Castle Environment Research Centre, undertook a major research programme, reviewing both agronomic and environmental aspects of P-advice for grassland.
    • Modelling phosphorus for grassland: agronomically and environmentally sustainable advice.

      Schulte, Rogier P. (Teagasc, 2006-01-01)
      In 2006, the Nitrates Directive (through S.I. 378 (Anon, 2006)) was implemented in Ireland, aimed at reducing nutrient losses from agriculture to water bodies, i.e. surface waters, groundwater and estuarine waters. This legislation introduced strict regulation of nutrient management on Irish farms. Thus far, nutrient management had largely been based on Teagasc advice (Coulter, 2004). However, in the new policy climate, in addition to advice, compliance with legal limits is also required. This significant change in the practicalities surrounding nutrient management led to a review of Teagasc nutrient (phosphorus and nitrogen) advice, based on the following considerations: Traditionally, nutrient advice had largely been based on fertiliser rates for economically optimal productivity, i.e. rates at which further fertiliser applications would not result in higher economic returns. Now, SI 378 of 2006 demands that nutrient application rates do not exceed crop (grass) demand, nor result in nutrient losses that may have a negative impact on water quality. Previous phosphorus (P) advice (Coulter, 2004) was similar for all soil types, and did not account for potentially different P-requirements, or indeed potentially different risks of P-loss to water between soils. Previous P advice was based on returning optimum crop yields. However, grassland management in Ireland is increasingly focussed on maximising the amount of herbage grazed in situ. With extended grazing seasons and an increasing share of the animal diet consisting of grazed herbage, the scope and flexibility of diet supplementation through straights and concentrates is reduced. An increasing proportion of dietary P must be obtained from this grazed herbage as a result. Therefore P fertiliser strategies should no longer be based on yield responses alone, but in addition sustain adequate herbage P-concentrations in order to ensure that the dietary P requirements can be met on a non-supplemented diet of grazed herbage. Against this background, Teagasc, Johnstown Castle Environment Research Centre, undertook a major research programme, reviewing both agronomic and environmental aspects of P-advice for grassland.
    • Nutrient management on intensive dairy farms in the southwest of Ireland

      Humphreys, James; Tracey, Mark; McNamara, Kevin (Teagasc, 2006-08-01)
      Intensive grass-based dairy farming relies on high inputs of nutrients that are now regulated under SI 378, 2006 (Good Agricultural Practice for Protection of Waters). This project studied nutrient management practices on twenty-one intensive dairy farms in the south-west of Ireland between 2003 and 2006. Mean stocking rate was 202 kg organic-N/ha deposited by grazing livestock. Overall fertiliser-N use on the farms decreased from 266 to 223 kg N/ha/yr during the study, with the rate of fertiliser-N in the first application each year decreasing from 49 to 33 kg N/ha, while the rate of fertiliser-N applied for first cut silage production also fell from 106 to 96 kg N/ha. These decreases were partly achieved by applying more slurry in springtime and by the introduction of white clover on five of the farms. While the limits on fertiliser-N use under SI 378 were exceeded on ten farms in 2003, the limits were exceeded on only two farms in 2006. Fertiliser-P usage declined from 12.0 to 10.2 kg P/ha/yr, and complied with the limits of SI 378 on thirteen of the farms in 2006. Mean Morgan’s extractable soil P concentration (STP) exceeded 10 mg/l on five farms, while the mean concentration exceeded 8 mg/l on ten farms. Phosphorus management, therefore, was close to that required by SI 378 on most farms. Slurry storage capacity met or exceeded the minimum requirements of SI 378 on eight farms; substantial investment in slurry storage facilities was necessary on thirteen farms. The mean N surplus on the farms declined from 277 to 232 kg N/ha/yr during the study due to a decline in total N input from 335 to 288 kg N/ha/yr over the same period. The mean efficiency of N-use increased from 17.9 to 20.2 %. The large variation in rates of fertiliser-N applied on farms with similar stocking rates suggests potential for further improvements in N use efficiency on some farms. Decreases in nutrient input levels can be partly attributed to increased farmer awareness, due to advice and record keeping from this study and the introduction of SI 378, and the increasing cost of nutrient inputs relative to output prices. In terms of fertiliser N and P use and soil P concentrations, complying with the limits in SI 378 does not require major changes in nutrient management practices on the majority of these intensive dairy farms.
    • Phosphorus management on Irish dairy farms post controls introduced under the EU Nitrates Directive

      Buckley, Cathal; Wall, David P.; Moran, Brian; O'Neill, Stephen; Murphy, Paul N. C.; Department of Agriculture, Food and the Marine (Elsevier, 2015-11-08)
      The Republic of Ireland was one of a minority of EU member states to include direct controls on chemical phosphorus (P) fertilisers in its EU Nitrates Directive National Action Plan, first introduced in 2006. This study estimates farm gate phosphorus balances and use efficiencies across 150 specialist dairy farms over the seven year period since these controls were introduced (2006–2012) using nationally representative data. Results indicate that P balances declined by 50% over the study period from 11.9 in 2006 to 6.0 kg ha− 1 in 2012. This decline was driven by a reduction in chemical fertiliser imports of 6.5 kg ha− 1. This is equivalent to a reduction of 281 kg of P and represents a cost saving of €812 per annum across the average farm. Phosphorus use efficiency also improved over the period from 60% in 2006 to 78% in 2012, peaking in 2011 at 88.3%. This was achieved while increasing milk solids output per hectare and per cow. Results of a random effects panel data model indicated that P balance and use efficiency are significantly influenced by factors such as fertiliser prices, stocking rates, land use potential, use of milk recording technology, contact with extension services and rainfall patterns.
    • A review of phosphorus and sediment release from Irish tillage soils, the methods used to quantify losses and the current state of mitigation practice

      Regan, J. T.; Fenton, Owen; Healy, Mark G. (Royal Irish Academy, 2012-03-20)
      Throughout the European Union (EU), agricultural soils with high phosphorus (P) status due to surplus fertiliser input have been identifi ed as a landscape pressure impacting on water quality. In Republic of Ireland, approximately 80% of agricultural land is devoted to grass, 11% to rough grazing, and 9% to arable cereal and crop production. Consequently, the majority of erosion research has focused on quantifying nutrient and sediment losses from grassland. Tillage soils are, however, more susceptible to erosion than grassland soils and, in general, have higher levels of soil P. This paper reviews the current state of research and the regulatory regime relating to diffuse P and sediment loss for tillage soils. It identifi es the key threats to soil quality associated with cultivated soils, and proposes the targeting and remediation of critical source areas for effective mitigation of P losses from tillage soils. A multiscaled approach is recommended, in which catchment and field-scale monitoring is complemented with controlled laboratory and small plot-scale rainfall simulation experiments to identify areas where P loss and soil erosion are at critical levels and may pose a threat to water quality. Catchment scale research will help to link critical source areas of sediment and P loss with hydrological pathways to surface waters in the catchment area. These areas can then be targeted for remediation in the river basin management plans.
    • A survey of fertiliser use in 2000 for grassland and arable crops.

      Coulter, B.S.; Murphy, W.E.; Culleton, Noel; Finnerty, E.; Connolly, Liam (Teagasc, 2002-05-01)
      The national farm survey data for 2000 was used as the basis for a fertilizer use survey. The farms which took part in the survey were randomly selected to represent the major farm systems and sizes using information from the CSO Census of Agriculture. Farms were classified into 6 main farm systems namely: dairying, dairying with other enterprises, cattle rearing, cattle with other systems, mainly sheep and tillage systems. These systems refer to the dominant enterprise in each group.