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«International 17 Workshop th Nitrogen The was jointly organised by Teagasc and AFBI Printed by Print Depot Suggested citation Authors, 2012. Title ...»

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References Bouwman, A.F., Boumans, L.J.M. and Batjes, N.H. 2002. Emissions of N2O and NO from fertilized fields: summary of available measurement data. Global Biogeochemical Cycles 16, 1080, doi:10.1029/2001GB001812.

IPCC (1996) Intergovernmental Panel on Climate Change. The science of climate change. In: Houghton JT, Meira Filho LG, Callander, BA, Harris, N, Kattenberg, A. and Maskell, K (eds) Climate change 1995. Cambridge University Press, Cambridge, p 22.

Linzmeier, W., Gutser, R. and Schmidthalter, U. 2001. Nitrous oxide emission from soils and from a 15N-labelled fertilizer with the new nitrification inhibitor 3,4-dimethyl pyrazole phosphate (DMPP). Biology and Fertility Soils 34, 103-108.

Menéndez S., Merino P., Pinto M., González-Mura C. and Estavillo J.M. 2006. 3,4-Dimethylpyrazol phosphate effect on nitrous oxide, nitric oxide, ammonia, and carbon dioxide emissions from grasslands. Journal of Environmental Quality 35, 973-981.

Menéndez S., López-Bellido R.J., Benítez-Vega J., González-Murua C., López-Bellido L. and Estavillo J.M. 2008.

Long-term effect of tillage, crop rotation and N fertilization to wheat on gaseous emissions under rainfed Mediterranean conditions. European Journal of Agronomy 28, 559-569.

Ortiz-Monasterio, J.L., Matson, P.A., Panek, J. and Naylor, R.L. 1996. Nitrogen fertiliser management of N2O and NO emissions in Mexican irrigated wheat. In: Transactions Ninth Nitrogen Workshop. Braunschweig, September, pp. 531Pereira, J., Fangueiro, D., Chadwick, D., Misselbrook, T.H., Coutinho, J. and Trindade, H. 2010. Effect of cattle slurry pre-treatment by separation and addition of nitrification inhibitors on gaseous emissions and N dynamics: A laboratory study. Chemosphere 79(6), 620-627.

Weiske, A., Benckiser, G., Herbert, T., Ottow, J.C.G. 2001. Influence of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) in comparison to dicyandiamide (DCD) on nitrous oxide emissions, carbon dioxide fluxes and methane oxidation during 3 years or repeated application in field experiments. Biology & Fertility of Soils 34, 109-117.

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Effect of nitrogen fertilization on nitrate leaching in relation to grain yield response in Sweden Delin, S.a, Stenberg, M.a a Department of Soil and Environment, Swedish University of Agricultural Sciences, Skara, Sweden

1. Background & Objectives Swedish farmers are encouraged to fertilize no more than the economic optimum in order to minimize nitrogen (N) leaching. Site-specific fertilization with respect to variation within fields could reduce N leaching further, but the effect would depend on the difference in leaching between fertilization above and below the optimum. To what extent the N leaching is affected above and below economical optimum varies in literature. According to Petersen and Djurhuus (2004) leaching is significantly increased already at rates below fertilizer recommendations, whereas Lord and Mitchell (1998) present data where leaching is affected only at rates above economical optimum. The objective of our study was to compare the effect of N fertilization on nitrate N leaching depending on grain yield response, i.e. above and below economical optimum in a cereal crop under Swedish weather conditions.

2. Materials & Methods Nitrate N leaching in response to different fertilizer N doses was investigated at two sites in southwest Sweden. Five field trials in spring oat were conducted in 2007, 2008 and 2009 on a loamy sand and in 2009 and 2010 on a silty clay. Each trial had five or seven N fertilization treatments (0of recommended rate of ammonium nitrate) distributed randomly within four blocks. The subsequent crops (year two) were winter wheat or spring barley, which received normal fertilization rates (100 kg N ha-1 in spring barley and 150 kg N ha-1 in winter wheat) in all treatments. On the loamy sand, soil water was sampled using ceramic suction cups (Djurhuus, 1990) installed in triplicate at 80 cm depth in each plot. On the clay soil, plots with separate drainage systems at 1 m depth were used. Each plot had a separate collector for drainage water comprising a measuring station where the amount of drainage water from each plot was measured with a wagging vessel, and flow-proportional water samples were collected from each plot automatically. Sampling from both systems was carried out bi-weekly during periods with water flow through drainage, from the time of fertilization (April) until June the following year. The samples from suction cups were analyzed for nitrate and from the separate drainage system for both total N and nitrate N. Nitrate N leaching was determined from nitrate concentrations in soil water and discharge, accounting for both direct and residual effects. Grain yield was measured plot-wise by combine harvester and reported at 85% dry matter. Grain yield was plotted against N fertilization rate and fitted second order polynomials were used to estimate economic optimum N fertilization rates, when price ratio of grain to fertilizer is 10:1. In order to compare the influence of fertilization on leaching above and below optimum, the deviation in leaching from that in the unfertilized treatment was plotted against the deviation in fertilization from economical optimum fertilization rate.

3. Results & Discussion On the sandy loam, the yield responded differently in different years, resulting in very different optimum N fertilisation rates (Figure 1A), ranging from 12 to 104 kg N ha-1. On the silty clay, yield response was better in 2009 resulting in a optimum N fertilization rate of 130 kg N ha-1 compared to 100 kg N ha-1 in 2010 (Figure 1B). Nitrate leaching was not significantly affected below economical optimum, i.e. as long as each kg N ha-1 of additional fertilisation led to at least 10 kg ha

<

Nitrogen Workshop 2012





increase in grain yield (Figures 1C and 1D). However, at larger N rates nitrate-N leaching increased exponentially at about 1-2 kg N ha-1 for every 5 kg of extra N fertilizer applied at the loamy sand (Figure 1C) and 0.5 kg N ha-1 leached for every 5 kg of extra N fertilizer applied at the silty clay (Figure 1D).

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4. Conclusion The difference in effect on leaching above and below economical optimum indicates that sitespecific N fertilization has the potential to reduce N leaching as long as fertilization will be kept at or below economic optimum at a larger area of the land.

References Djurhuus, J. 1990. Sammenligning af nitrat i jordvand udtaget med sugkopper og ekstrahert fra jordprøver.

Landbrugsministeriet, Statens Planteavlsforsøg, Særtryk af Tidsskrift for Planteavl 94, 487-495.

Lord, I.E. and Mitchell, R.D.J. 1998. Effect of nitrogen inputs to cereals on nitrate leaching from sandy soils. Soil Use and Management 14, 78-83.

Peterssen, J. and Djurhuus, J. 2004. Sammenhæng mellem tilførsel, udvaskning og optagelse af kvælstof i handelsgødede, kornrige sædskifter. DJF rapport markbrug nr. 102, 55 s.

Nitrogen Workshop 2012

Effect of non-fertilized winter grazing dairy production on soil N balances and soil N dynamics in a clay-loam soil Necpalova, M.a,b, Phelan, P.a,b, Casey, I.b, Humphreys, J.a a Animal and Grassland Research and Innovation Centre, Teagasc Moorepark, Fermoy, Co Cork, Rep of Ireland b Department of Chemical and Life Sciences, Waterford Institute of Technology Cork Road, Waterford, Rep of Ireland

1. Background & Objectives Soil surface nitrogen (N) balances and soil soluble N pools are often analysed to evaluate nutrient management practices on the soil surface. Winter grazing under moist temperate conditions has a high potential to affect soil N dynamics. The objective of this study was to investigate the effect of non-fertilized winter grazing dairy production on soil surface N balances and soil soluble N dynamics in a clay loam soil profile on a dairy farm in south Ireland over two production years.

2. Material & Methods The systems were: (i) ES-100N–Early spring calving with 100 kg ha-1 of fertilizer N (Feb, March, Apr):grazed from Feb to Nov and stocked at 2.1 cows ha-1; (ii) ES-0N–Early spring calving without fertilizer N: grazed from Feb to Nov and stocked at 1.6 cows ha-1; (iii) LS-0N–Late spring calving without fertilizer N: stocked at 1.7 cows ha-1 between calving and 1st Sept and then 1.3 cows ha-1 until the end of Jan since extra 3.7 ha was added to the system area. Each system consisted of six paddocks (1 ha) on a clay-loam soil (28% clay).The excreta from housed animals were collected in a single tank. Soil surface N balances for each paddock and each year were calculated in accordance with the methodology of the Organisation for Economic Co-operation and Development (OECD, 2001). Inputs included N entering the soil through the soil surface as mineral fertilizer N, slurry, animal excreta, atmospheric deposition and white clover biological N fixation (BNF).

Outputs consisted of N leaving the soil as harvested and grazed herbage. The soil surface N surplus was calculated as the difference between N inputs and outputs. Nitrogen fluxes were quantified and expressed on an annual basis. The quantities of N excreted by animals were calculated as the difference between N intake in feeds and N output in milk and calves, accounting for live weight change (Powell et al., 2006). Nitrogen excreted in each paddock was estimated according to the number of grazing days in the particular paddock. Atmospheric deposition was measured in situ.

Biological N fixation was estimated using an empirical model (Humphreys et al., 2008), based on herbage yields and white clover content. Nitrogen removed in herbage was estimated from pregrazing and pre-harvest herbage cuts (Humphreys et al., 2008) and herbage N content. Soil samples were taken from four paddocks per system eight times during the study period. At each sampling, 15 cores per paddock were taken using a hydraulic auger. Each core was subdivided into depths: 0 to 0.3 m, 0.3 to 0.6 m and 0.6 to 0.9 m and bulked to a composite sample at each depth within each paddock. Immediately after sampling, extracts were obtained by shaking in 2M KCl continuously for three hours at solution ratio of 2:1 (400ml:200 g, ratio v/w). Ammonium N and total oxidised N (TON) were determined using Aquakem 600 Discrete analyser. Total soluble nitrogen (TSN) was measured using a Shimadzu TOC-VCPH analyzer. Soluble organic N (SON) was calculated as the difference between TSN and inorganic N (TON+Ammonium N). Soil bulk density (BD) was measured as described by Blake and Hartge (1986). The results were expressed on an area basis using soil BD data for each depth. The experimental unit of the balances was a single paddock. The N flows were subjected to ANOVA (SAS Institute, 2009) examining the effects of the system, year and their interaction. Soil results were analysed as a repeated measure investigating the effect of the system, sampling depth and date, and their interactions. Simple linear regression was used to identify parameters that influenced soil N content.

Nitrogen Workshop 2012

3. Results & Discussion Soil surface balances for the systems are presented in Table 1. Linear regression revealed a positive correlation between total N inputs and N uptake by herbage (r2=0.30, P0.05) and between total N inputs and TSN (r2=0.43, P0.05). Total soluble N was also correlated with N surplus (r2=0.36, P0.05). All soluble N species decreased with sampling depth (P0.0001) and exhibited high temporal variation (P0.0001). Soluble inorganic N content at each sampling depth (0.9m) was not significantly affected by system operated on the soil surface. However, SON was influenced by system and sampling date interaction down to 0.6 m (P0.05). In all systems, TON at each sampling depth increased between March and August and then decreased during winter months due to N leaching. Ammonium N and SON were not as dynamic as TON and both of them displayed a similar seasonal pattern under all systems. Ammonium N (r2=0.72, P0.00001) and SON (r2=0.38, P0.0001) were positively related to gravimetric soil moisture content. In contrary, TON content was negatively related to effective rainfall (r2=0.35, P0.0001) and positively related to soil temperature (r2=0.47, P0.0001). This signifies its dependence on microbial activity and biochemical processes, and also its susceptibility to leaching during winter.

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4. Conclusion The non-fertilized winter grazing dairy production system operated on a heavy textured clay loam soil did not affect annual soil surface N surplus and soil soluble N dynamics in the soil profile compared to the other systems. Seasonal changes in soluble N pools were driven by soil moisture content and soil temperature, which are the most important factors controlling microbial activity and biochemical processes.

Acknowledgement This study was funded by the Department of Agriculture, Fisheries and Food (RSF07-511) References Blake G.R. and Hartge K.H. 1986. Bulk Density. Agronomy 9, 363-375 Humphreys J. O’Connell, K. and Casey I.A. 2008. Nitrogen flows and balances in four grassland-based systems of dairy production on a clay-loam soil in a moist maritime environment. Grass and Forage Science 63, 467-480.

OECD (2001) Methods and Results. In: Environmental Indicators for Agriculture, vol. 3. Organisation for Economic Co-operation and Development, Paris, France.

Powell, J.M., Wattiaux, M.A., Broderick, G.A., Moreira, V.R. and Casler, M.D. 2006. Dairy diet impacts on fecal chemical properties and nitrogen cycling in soils. Soil Science Society of America Journal 70, 786–794.

Nitrogen Workshop 2012

Effect of non-fertilized winter grazing dairy production system based on a clay-loam soil on N leaching to groundwater Necpalova, M.a,b, Fenton, O.c, Casey, I.b, Humphreys, J.a a Animal and Grassland Research and Innovation Centre, Teagasc Moorepark, Fermoy, Co Cork, Rep of Ireland b Department of Chemical and Life Sciences, Waterford Institute of Technology Cork Road, Waterford, Rep of Ireland c Environmental Research Centre, Teagasc, Johnstown Castle, Co. Wexford, Rep of Ireland



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