• 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.
    • C:N:P stoichiometry and nutrient limitation of the soil microbial biomass in a grazed grassland site under experimental P limitation or excess

      Griffiths, Bryan S; Spilles, Annette; Bonkowski, Michael (Biomed Central, 2012-06-21)
      Introduction: The availability of essential nutrients, such as nitrogen (N) and phosphorus (P), can feedback on soil carbon (C) and the soil microbial biomass. Natural cycles can be supplemented by agricultural fertiliser addition, and we determined whether the stoichiometry and nutrient limitation of the microbial biomass could be affected by an unbalanced nutrient supply. Methods: Samples were taken from a long-term trial (in effect since 1968) with annual applications of 0, 15 and 30 kg P ha−1 with constant N and potassium. Soil and microbial biomass CNP contents were measured and nutrient limitation assessed by substrate-induced respiration. Linear regression and discriminant analyses were used to identify the variables explaining nutrient limitation. Results: Soil and biomass CNP increased with increasing P fertiliser, and there was a significant, positive, correlation between microbial biomass P and biomass C, apart from at the highest level of P fertilisation when the microbial biomass was over-saturated with P. The molar ratios of C:N:P in the microbial biomass remained constant (homeostatic) despite large changes in the soil nutrient ratios. Microbial growth was generally limited by C and N, except in soil with no added P when C and P were the main limiting nutrients. C, N and P, however, did not explain all the growth limitation on the soils with no added P. Conclusions: Increased soil C and N were probably due to increased net primary production. Our results confirm that C:N:P ratios within the microbial biomass were constrained (i.e. homeostatic) under near optimum soil conditions. Soils with no added P were characterised by strong microbial P limitation and soils under high P by over-saturation of microorganisms with P. Relative changes in biomass C:P can be indicative of nutrient limitation within a site.
    • 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 autumn/spring nitrogen application date and level on dry matter production and nitrogen efficiency in perennial ryegrass swards

      O'Donovan, Michael; Delaby, L; Stakelum, G; Dillon, Pat (Teagasc, 2004)
      The influence of autumn/spring N-application date and level on grass dry matter (DM) production in spring and on N uptake, recovery and efficiency were examined over 3 years (1998, 1999 and 2000, identified as Year 1, 2 and 3, respectively). Seven N-application dates were investigated in years 2 and 3 while four application dates were investigated in Year 1. The application dates were 21 October (T1), 11 November (T2), 2 December (T3), 23 December (T4), 12 January (T5), 3 February (T6) and 23 February (T7). Three N-application rates (kg N/ha) were used: 30 (N30), 60 (N60) and 90 (N90) plus a zero-N control (N0). Herbage DM yields were determined on: 18 March (H1) and 8 April (H2). Two herbage masses (HM) (40 mm above ground level) at initial Napplication date were investigated: a high HM (HHM) of 500 kg DM/ha and a low HM (LHM) of 100 kg DM/ha. The HM at initial N-application date in Year 1 was HHM, in Year 2 LHM and in Year 3 both HHM and LHM. There was a significant effect of Year (P<0.001), HM (P<0.001), N-application date (P<0.001) and N level (P<0.001) on DM production at both H1 and H2. At H1 there was a significant interaction between N-application date and level for DM production. N-application date had a significant (P<0.001) effect on N recovery at both H1 and H2. The highest N recovery rate at the two harvest dates was at T5, while the lowest was at T1 and T2. At H1 and H2 there was a significant effect (P<0.001) of application date on response to applied N. The responses were 7.5, 8.0, 8.3, 12.0, 15.7, 7.3 and 5.6 (kg DM/kg N) (s.e. 1.88) for T1 to T7,respectively, at H1, while the corresponding values at H2 were 10.3, 8.7, 6.1, 15.2, 17.6,11.4 and 15.1 (s.e. 1.88). At H2 the response to applied N was 15.6, 11.5 and 9.1 (kg DM/kg N) for N30, N60 and N90, respectively (P<0.05). Regression analysis indicated that highest DM production was achieved with T5 for both H1 and H2 harvest dates, while the lowest responses were associated with T1, T2 and T3 application dates.
    • The effect of dietary crude protein concentration on growth performance, carcass composition and nitrogen excretion in entire grower-finisher pigs

      Carpenter, D. A.; O'Mara, Frank P.; O'Doherty, John V (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
      Two experiments, a performance experiment (n = 72) and a nitrogen balance (n = 16) experiment were conducted to evaluate the effects of dietary crude protein (CP) concentration on growth performance, carcass characteristics and nitrogen excretion of pigs. Dietary CP concentrations in experimental diets (g/kg) were 207.5, 170, 150 and 122.5 for treatments 1, 2, 3 and 4, respectively, and were offered to individually-fed entire-male grower-finisher pigs (45 to 95 kg). The diets were formulated to contain 13.7 MJ digestible energy and 11 g total lysine/per kg. Synthetic lysine, methionine, threonine and tryptophan were added to achieve ideal protein status. There was a linear increase in food intake as CP concentration decreased (P < 0.05). There was a quadratic response in daily live-weight gain and food conversion ratio (P < 0.05) to the change in CP concentration (P < 0.05), with an improvement in daily gain and food conversion ratio occurring as CP concentration declined to 150 g/kg and a deterioration in these parameters thereafter. There was a linear decrease (P < 0.05) in lean meat proportion as CP concentration decreased. There was a linear decrease in urinary output (P < 0.05), urinary pH (P < 0.01) and slurry pH (P < 0.05) as dietary CP concentration decreased. There was a quadratic response in urinary nitrogen output (P < 0.05), total nitrogen output (P < 0.05) and N utilization as dietary CP decreased. In conclusion, a dietary CP level of 150 g/kg was optimal in terms of growth performance and reduced nitrogen excretion.
    • The effect of phase-feeding on the growth performance, carcass characteristics and nitrogen balance of growing and finishing pigs.

      Garry, B.P.; Pierce, K.M.; O'Doherty, J.V. (Teagasc, Oak Park, Carlow, Ireland, 2007)
      A completely randomised design experiment was conducted to determine if grouphoused grower-finisher pigs (43.9 to 95 kg) show differences in performance and nitrogen utilisation when provided with a single high lysine diet (11 g/kg) or with a mean lysine concentration of 9.5 g/kg, either as a single diet or as a series of two or four diets. Four hundred and forty pigs were assigned to four dietary treatments. The experimental treatments were (total lysine) (1) 11 g lysine/kg from day 0 to slaughter (SHD) (2) 10.5 g/kg lysine from day 0 to day 28 and 8.5 g/kg lysine from day 29 to slaughter (DFD) (3) 9.5 g/kg lysine from day 0 to slaughter (RFD) and (4) 11 g/kg lysine from day 0 to day 14, 10 g/kg lysine from day 14 to day 28, 9.0 g/kg lysine from day 28 to day 42 and 8.0 g/kg lysine from day 42 to slaughter (PFD). The estimated lysine concentration required for treatments RFD, DFD and PFD was 9.5 g/kg for group-housed pigs. All diets were pelleted and formulated to have a net energy concentration of 9.8 MJ/kg. The pigs were group fed in mixed-sex pens using single space feeders (11 pigs/feeder, 6 boars and 5 gilts). Daily feed intake was lower (P < 0.05) in treatment SHD in comparison to RFD and DFD during the overall grower-finisher period (2.08 vs 2.18 and 2.23 kg/day, respectively). Lysine conversion ratio was poorer for pigs on treatment SHD compared with DFD (P < 0.01), RFD (P < 0.01) or PFD (P < 0.001), while food conversion ratio was better for pigs on treatment SHD compared with treatments DFD (P < 0.01) and PFD (P < 0.001) during the grower-finisher period (2.31 vs 2.43 and 2.48 kg/kg, respectively). N intake and excretion were higher (P < 0.001) for pigs offered SHD compared to all other treatments (3.93 vs 3.51, 3.42, 3.40 kg and 2.56 vs 2.14, 2.03, 2.10 kg for SHD vs DFD RFD and PFD for intake and excretion, respectively). N utilisation coefficient was lower for pigs on treatment SHD than pigs on treatments DFD (P < 0.01), RFD (P < 0.001) or PFD (P < 0.01). In conclusion, phase feeding did not result in any benefit to pig performance, N excretion, N utilisation or carcass characteristics when compared with a single diet that was formulated to match the animal’s requirement for lysine (treatment RFD).
    • 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%.
    • Nitrogen dynamics in a mature Miscanthus x giganteus crop fertilized with nitrogen over a five year period

      Finnan, John; Burke, B. (Teagasc (Agriculture and Food Development Authority), Ireland, 2014)
      The objective of this study was to investigate N dynamics and response to N fertilization in a mature crop of Miscanthus x giganteus. A crop of Miscanthus x giganteus sown in 1994 was fertilized with five N rates (0, 38, 63, 90 and 125 kg N/ha/year) over a five year period (2008–2012) in Carlow, Ireland. Foliar chlorophyll concentrations were directly related to N fertilization level throughout the study and rose after N applications until July before falling with the onset of N remobilisation. Shoot numbers were unaffected by N fertilization until the final years of the study when they increased with N level. Crop height was unaffected by fertilization in the early years of the study but in the final years of the study, it increased with N level until July after which the effect diminished. There was a small but significant stimulation of harvested biomass yields in autumn (average 15 t/ha) with increasing N fertilization, but there was no effect on harvested yields in spring (average 10.5 t/ha). The N concentration in the rhizome network gradually built up during the course of the study and was proportional to N application. Aboveground biomass N content was also proportional to N application. Nitrogen remobilisation between the October and February harvests was small; abscissed leaves accounted for most of the N loss over this period. The deleterious environmental consequences of N fertilizer may outweigh any potential economic benefits if increases in biomass production are small or non-existent.
    • 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.
    • 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.