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5.71) (Figure 1). The mean stocking density (kg organic N ha-1) was not significantly different (P0.05) than in earlier similar studies conducted on Irish dairy farms between 2003 and 2006 (Treacy et al., 2008) and in 1997 (Mounsey et al., 1998); 183 kg N ha-1 (s.e. 6.75) in the current study, 202 kg N ha-1 (s.e. 6.75) between 2003 and 2006 and 190 kg N ha-1 (s.e. 8.93) in 1997.
However, the proportion of dairy livestock (72% of total livestock) on farms in the present study was higher than previous studies (approximately 64%). This indicates that the dairy farmers in the current study were more specialized than in the previous studies. This is in line with national trend towards increased specialisation on dairy farms (Hennessy et al., 2010). The mean N surplus in the present study (196 kg N ha-1) was lower than found by Treacy et al. (2008) (244 kg N ha-1) and Mounsey et al. (1998) (304 kg N ha-1). The mean N use efficiency in the current study (28%) was substantially higher than Treacy et al. (2008) (19.5%) and Mounsey et al. (1998) (17%).
Figure 1. N use efficiencies relative to N surpluses on 21 Irish dairy farms in 2010
4. Conclusions The mean N surplus was lower and N use efficiency was much higher than similar previous studies in Ireland indicating that there has been improvement in N use efficiency on dairy farms after implementation of Nitrates Regulations.
Acknowledgements The authors acknowledge financial support from the ERDF Interreg IVB Dairyman project and the Teagasc Walsh Fellowship Scheme.
References ARC (Agricultural Research Council). 1994. The nutrient requirements of ruminant livestock. Technical review by an Agricultural Research Council Working Party. CAB International, Oxon, UK.
Hennessy, T., Moran, B., Kinsella, A., and Quinlan, G. 2011. Teagasc National Farm Survey 2010. Athenry, Ireland, Teagasc.
McDonald, P., Edwards, R.A., Greenhalgh, J.F.D. and Morgan, C.A. 1995. Animal Nutrition (5th edition). Prentice Hall, UK.
Mounsey, J., Sheehy, J., Carton, O.T. and O’Toole, P. 1998. Nutrient management planning on Irish dairy farms. End of project report, ARMIS 4347, Teagasc, Dublin.
S.I. (Statutory Instrument) No. 378 of 2006. European Communities (Good Agricultural Practice for Protection of Waters) Regulations 2006, The Stationary Office, Dublin, 49 pages.
S.I. (Statutory Instrument) No. 101 of 2009. European Communities (Good Agricultural Practice for Protection of Waters) Regulations 2009, The Stationary Office, Dublin, 49 pages.
S.I. (Statutory Instrument) No. 610 of 2010. European Communities (Good Agricultural Practice for Protection of Waters) Regulations 2010, The Stationary Office, Dublin, 53 pages.
Treacy, M., Humphreys, J., Mc Namara, K., Browne, R. and Watson, C.J. 2008. Farm-gate nitrogen balances on intensive dairy farms in the south-west of Ireland, Irish Journal of Agricultural and Food Research 47, 105-117.
Nitrogen Workshop 2012
Nitrous oxide emission determining factors for a clay soil in Sweden Nylinder, J.a, Kasimir Klemedtsson, Å.a, Stenberg, M.b a Department of Earth sciences, University of Gothenburg.
b Rural Economy and Agricultural Society of Skaraborg and Division of precision agriculture, Department of soil sciences, SLU.
1. Background & Objectives Nitrous oxide (N2O) emission is inevitable whenever cultivating soil. For N2O estimations the IPCC emission factors are often used which is a simplification sometimes needed, but for more detailed analysis many other factors have been found important for the degree of emission. In the agricultural system not only fertiliser or other additions are the cause for emissions, also soil disturbance activities can increase nitrogen (N) mineralisation which deliver N to both plants and microbial communities. Poor crop establishment or N surplus increase the risk of both N2O emissions and N leaching. More reliable estimation methods are needed than what we found in an earlier study on estimating emission due to biofuel production where no estimation method like the IPCC or others were able to predict the emission (Kasimir-Klemedtsson and Smith, 2011). The aim in this project is to identify soil and management factors influencing the N2O emission from clay soils, representative for Swedish agricultural conditions. Better abilities to estimate emissions based on understanding of the whole agricultural and soil system may guide us to crops and management having low emissions and give more detailed calculation methods.
2. Materials & Methods We examined the effect of management influences on the emissions using a mechanistic processbased model, the CoupModel (Jansson and Karlberg, 2004), and data from two organic crop rotation sequences; field beans-spring wheat and green manure-winter rye. In this study the source data was collected from Logården (west Sweden), where three crop production systems, organic, integrated and conventional farming, have been managed continuously since 1991. Emissions of N2O were measured by the static chamber method where sampling was carried out every second week between 2004 and 2007. During these years, also nitrate leaching and water discharge was measured every day together with occasional measurements of soil N, N in grain and soil water content.
3. Results & Discussion In an earlier study by Nylinder et al. (2011) key soil processes, controlling N2O production and emission from two organic fields, were found to be crop N uptake, nitrification, denitrification and also abiotic parameters. A recent simulation of one of the integrated fields (2004-2007) selecting an ensemble of runs, based on measured plant and soil N and total N2O emission, did show important variables for N2O emission to be; total soil nitrate content, plant N uptake and leaching of nitrate (Figure 1). It is obvious that the dynamics of soil nitrate is partly controlled by plant N uptake and leaching of nitrate (Figure 1). This is important knowledge as a basis to further investigation of soil disturbances by ploughing and compaction which we will show simulation results of at this workshop.
Figure 1. Simulated N2O emission, soil nitrate content, nitrate leaching and nitrate uptake by plant from an integrated crop rotation field at Logården, 2004-2007.
4. Conclusion By the CoupModel simulation it is possible to find influencing factors like soil nitrate content which, in as in this study, fluctuate over time. We will further investigate and present both ploughing and compaction effects on soil properties to find possible connections to N2O emission.
IPCC. 2006. N2O emission from managed soils, in: Guidelines for National Greenhouse Gas Inventories, Vol. 4:
agriculture, Forestry and Other Land Use, Chapter 11, edited by: Eggleston, H. S., Buendia, L., Miwa, K., Ngara T., Tanabe K., IGES, Hayama, Japan, 2006. Jungkunst, H. F., Freibauer Kasimir Klemedtsson, Å.and Smith, K.A. 2011. The significance of nitrous oxide emission from biofuel crops on arable land: a Swedish perspective. Biogeoscience 8, 3581-3591.
Nylinder, J., Stenberg, M., Jansson, P-E., Kasimir Klemedtsson, Å., Weslien, P. and Klemedtsson, L. 2011. Modelling uncertainty for nitrate leaching and nitrous oxide emissions based on a Swedish field experiment with organic crop rotation, Agriculture, Ecosystem and Environment 141, 167-183.
Jansson, P.E. and Karlberg, L. 2004. Coupled heat and mass transfer model for soil-plant-atmosphere systems TRITALWR report 3087. Royal Institute of Technology, Department of Land and Water Resources Engineering Stockholm, Sweden. http://www2.lwr.kth.se/CoupModel/index.html Nitrogen Workshop 2012 Performance of nitrogen fertilizer rates for winter oilseed rape Ruža, A.a, Gaile, Z.a, Balodis, O.b, Kreita, D. a, Katamadze, M.a a Latvia University of Agriculture b Latvia University of Agriculture, Research and Study Farm ‘Vecauce’
1. Background & Objectives Nitrogen as a critical nutrient element for winter oilseed rape is investigated quite frequently in Europe.
Adjustment of N-fertilizer strategies becomes a more and more important factor as soil conditions, water availability and temperature influence plant growth and yield of cultivars. Different important courses in nitrogen utilization had been discussed in workshops, such as influence of environmental factors on plant growth and N-efficiency, integrated N-management strategies and further crop management practices combined with nitrogen provision (Rathe et al., 2006). Different experiments across Europe with similar themes like such as the effect of nitrogen fertilizer on yield and yield formation in winter oilseed rape show a tendency of higher yielding types of winter oilseed rape to respond typically to more N fertilizer (Wójtowicz et al., 1999). The aim of our trials was to determine indicators of the nitrogen fertilizer utilization for different nitrogen rates depending on specific year in variable meteorological conditions.
2. Materials & Methods Field trials (starting in 2009-2011) with winter oilseed rape (Brassica napus ssp. oleifera) cultivar ‘Catalina’ were conducted in the Research and Study farms ‘Vecauce’ and ‘Pēterlauki’ of the Latvia University of Agriculture. Nitrogen fertilizer rates used were: 1. N0P0K0 - check, 2. PK background, the following with a step N30 to N210 kg ha-1. Seeds and straw were analyzed. Outcome, plant nutrient balance and utilization coefficients were calculated. Total N was determined by the Kjeldahl method.
Nitrogen outcome was calculated based on total nitrogen content in seeds and straw. Apparent recovery
fraction (ARF) for nitrogen was calculated using (1) formula (Montemurro et al., 2007):
3. Results & Discussion The seed yield on average was within 2.0 t ha-1 to 4.7 t ha-1 (Figure 1). High seed yield - 5.34 t ha-1 was obtained with nitrogen fertilizer rate N150 at ‘Pēterlauki’ in 2009. The highest seed yields were achieved in variants N120 or N150 in all trial years; higher nitrogen fertilizer treatments did not increase seed yield significantly (P0.05), with only total N content in seeds increasing in treatments with nitrogen fertilizer up to N180. Total nitrogen content (TNC) in straw increased proportionally as nitrogen rates increased from 0.67 % in the control to 0.96% in N210 - consequently total outcome of nitrogen per unit increased as a higher step of the fertilizer rate was used.
Total outcome of nitrogen with total plant mass was twice as much in fertilizer treatment N210 than in check. Apparent recovery fraction for nitrogen in all fertilizer rates, except N30, was above 0.40 with the highest result in rate N120, but the result was different according to years and was within 0.35 to
0.90 in higher yielding rates (N120 and N150).
4. Conclusions Seed yields of winter oilseed rape increased with increasing nitrogen fertilizer rates up to N120-150 kg haFurther increases in fertilizer rates did not give significant (p0.05) seed yield increase. AFR is dependent on meteorological conditions in specific years and locations of trial sites.
References Montemurro, F., Convertini, G. and Ferri, D. 2007. Nitrogen application in winter wheat grown in Mediterraneum Conditions: Effects on nitrogen uptake, utilization efficiency, and soil nitrogen deficit. Journal of Plant Nutrition, vol 30 (10), 1681-1703.
Rathke, G.-W., Behrens, T. and Diepenbrock, W. 2006. Integrated nitrogen management strategies to improve seed yield, oil content and nitrogen efficiency of winter oilseed rape (Brassica napus L.): A review. Agriculture, Ecosystems and Environment 117, 80-108.
Wójtowicz, M., Wielebski, F. and Krzymański, J. 1999. Yield structure of double low winter oilseed rape (Brassica napus l.) varieties in different environmental conditions. Proceedings of 10th International Rape Congress, Canbera, Australia,
1999. Available in www.regional.org.au/au/gcirc/index/references.htm
Nitrogen Workshop 2012
Prediction of nitrous oxide emissions from Irish arable lands using the ECOSSE model M.I. Khalila,b, M. Richardsc, M. Abdallad, P. O’Briena, J. U. Smithc, P. Smithc and C. Müllerb a Climate Change Research Programme, Environmental Protection Agency, Wexford, Ireland (e-mail: email@example.com).
b School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
c, Institute of Biological & Environmental Sciences, University of Aberdeen, Scotland, United Kingdom.
d School of Botany, Trinity College Dublin, Dublin 2, Ireland.
1. Background & Objectives Agriculture and associated land-use changes have large impacts on carbon (C) and nitrogen (N) cycling in soil systems and contribute about one-third of global greenhouse gas (GHG) emissions to the atmosphere. In the Republic of Ireland, agricultural activity is estimated to be responsible for 30% of the anthropogenic GHG emissions (McGettigan et al., 2010) and agricultural emissions remain a key component of the 20% reduction required by 2020. Reduction in the uncertainty in estimates of GHG emissions is a current research focus. This is particularly important for nitrous oxide (N2O) because it has a greater radiative forcing potential and so errors in estimates have a greater impact than for methane (CH4) and carbon dioxide (CO2). Process-based modelling could greatly enhance the accuracy of estimates so improving national inventories. Our aim is to evaluate estimates of N2O emissions from agricultural land provided by a process-based model, allowing accuracy of reporting to be quantified, and selection of mitigation options to be improved.