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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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The experimental setup comprises three replicated buffer zone treatments, shown in Figure 1. Plots are hydrologically isolated on a uniform slope of approximately 5º and comprise a 40 m x 10 m drained grassland plot with (1) no buffer (control); (2) a 6 m wide buffer zone; and (3) a 6 Figure 1. Plan of the Buffer Zone Experiment at Rothamsted Research, North m wide buffer zone with a Wyke, Devon, England.

PRB installed upslope. The PRB material consists of a wheat straw carbon (C) source, for denitrification processes, and gypsum (derived from crushed plasterboard) for P removal (Grimsey, 2011). The plots were amended with slurry in October 2011, in line with intensive grassland management. Surface and sub-surface flow samples were collected using flow proportional sampling during the storm of 12th-13th December 2011, which had a precipitation total of 23.2 mm. Samples were analysed for dissolved (0.45 µm)

Nitrogen Workshop 2012

total oxidised N (TOxN) and ammonium-N (NH4+) using a Thermo Fischer Aqua Kem 250, discrete photometric analyser.

3. Results & Discussion Results from the analyses of the 12th-13th December 2011 storm samples are shown for each treatment in Figure 2.

Sub-surface flow samples for the control (rep. 1) and the buffer zone with PRB (rep.

3) were not taken due to equipment failure. Mean total flow volumes (n = 3; ± standard error) for the surface flow of the control, buffer and buffer with PRB were 4.9 ± 0.6, 3.0 ± 0.7, 4.8 ± 2.3 m-3 respectively and for Figure 2. Mean concentrations of TOxN and NH4+ from 12th-13th December the sub-surface flow of the storm for each treatment and standard error bars where n =3 for all except subcontrol, buffer and buffer surface flow Control and Buffer 6 m + PRB where n =2.

with PRB were 15.7 ± 0.2, 19.5 ± 4.9 and 17.0 ± 2.2 m-3 respectively. Highest mean values of TOxN were found in the buffer treatment at 0.87 mg L-1 for both surface and sub-surface flow, whereas minimum mean values were 0.05 mg L-1 in the surface flow of the buffer with PRB.

Highest mean NH4+ concentrations occurred in the surface flow and lowest mean concentrations in the sub-surface flow of the buffer with PRB of 0.32 mg L-1 and 0.03 mg L-1 respectively. A general trend of higher mean NH4+ values in the buffer and buffer with PRB treatments relative to the control in the surface flow is observed. However, variation amongst the concentrations of TOxN and NH4+ is not significant (p 0.05 ANOVA Genstat 14) for any of the treatments. This is not surprising due to the PRB being newly installed and it may require time to commence full functionality. Also the processes (e.g. denitrification) that are primarily responsible for nutrient transformation and removal are microbiologically driven, and typically operate at low levels during colder, winter months. These results imply that where buffer zones and buffer zones with PRBs are artificially drained they have little impact on the capturing and transformation of TOxN and NH4+.

4. Conclusions Results suggest that the presence of buffer zones or buffer zones with PRBs in drained intensive grasslands do not result in significant changes in water quality and/or that N loading of the treatments was low due to flushing from a previous storm or due to plant uptake. Efficacy of buffer strips and PRBs requires assessment over a range of storm intensities and seasonally different antecedent conditions, particularly following amendment of a N source References DEFRA 2010. Entry Level Stewardship Handbook. In: Department for the Environment, Farming and Rural Affairs (ed.) Third ed. London: Natural England.

Grimsey, V. 2011. Evaluation of different permeable reactive barrier (PRB) materials for the control of diffuse pollutants from agriculture, M.Sc. Dissertation, Lancaster University, Lancaster, UK.

Schipper, L.A., Robertson, W.D., Gold, A.J., Jaynes, D.B. and Cameron, S.C. 2010. Denitrifying bioreactors-An approach for reducing nitrate loads to receiving waters. Ecological Engineering, 36, 1532-1543.

Nitrogen Workshop 2012

Nitrogen mass balance in a coastal lowland declared vulnerable to nitrate (WFD 2000/60/EC):

the relevance of secondary canals in excess nitrogen removal Castaldelli, G.a, Pierobon, E.a, Soana E.b, Salemi E.c, Aschonitis V.G.d, Colombani N.c, Mastrocicco M.c, Bartoli M.b a Department of Biology and Evolution, University of Ferrara, Ferrara, Italy b Department of Environmental Sciences, University of Parma, Parma, Italy c Department of Earth Sciences, University of Ferrara, Ferrara, Italy d School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece

1. Background & Objectives The Po di Volano Basin (687.5 km2) is a recently reclaimed alluvial territory, located south of the Po River Delta (northeaster Italy) and characterized by flat topography, intense agriculture and low population density. Under European Water Framework Directive (2000/60/EC) the whole basin has been designated as nitrate-vulnerable zone (NVZ). The objective of this work is to calculate a comprehensive nitrogen budget, both for superficial soils and the hydrological network, and compare individual terms to assess their reliability, particularly with respect to soil nitrogen losses and removal processes via denitrification.





2. Materials & Methods Nitrogen soil budget was carried out on annual basis from 2006 to 2008, according to Oenema et al.

(2003). The main inputs and outputs for N cycle in terrestrial agroecosystems were considered with associated errors and included in the equation modified from Isidoro et al. (2006). Balance calculations were performed at a spatial resolution of 26 municipalities, expressed as t N yr-1, and aggregated on the watershed scale, using ArcView GIS 3.2 software (ESRI, California) (Soana et al., 2011). Input from urban and point sources were not taken into account in the final balance, because their magnitude resulted negligible. The nitrogen loads of the hydrological network were calculated according to Kronvang and Bruhn (1996), and Letcher et al. (2002), using discharge data, registered monthly and weekly by Hydraulic Authorities and nitrogen concentrations, measured monthly by the Emilia-Romagna Environmental Protection Agency.

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The hydrological network exported 2.707 ± 256 tN y-1 of nitrogen to the coastal area, of which 36% in form of nitrate. The mean annual removal of nitrogen was 1.112 ± 285 tons, with the highest values in summer months.

4. Discussion & Conclusion The nitrogen balance in soils (Σinput – Σoutput= 5.869 t N y-1) was not closed and the excess was not explained by the mere removal in the canal network, much lower. This was likely due to an underestimate of denitrification in soils, calculated by using coefficients taken from literature. This observation is also supported by the results of field and laboratory experiments, performed in the same soils, which indicate higher rates of denitrification (Mastrocicco et al., 2011; 2012).

Regardless of, the secondary canals’ network has evidenced a potential to effectively mitigate the excess of nutrients from diffuse sources of pollution, particularly in summer when the eutrophication risk is at highest. Simulations performed in this study highlight the importance of conservative management of emergent vegetation, in order to improve nitrogen removal in vulnerable watersheds.

References Isidoro D., Quìlez D. and Aragues R. 2006. Environmental Impact of Irrigation in La Violada District (Spain): II.

Nitrogen fertilization and nitrate export patterns in drainage water. Joulnal of Environmental Quality 35, 776-785.

Kronvang B. and Bruhn A.J. 1996. Choice of sampling strategy and estimation method for calculating nitrogen and phosphorus transport in small lowland streams. Hydrological Processes 10 (11), 1483-1501.

Letcher R.A., Jakeman A.J., Calfas M., Linforth S., Baginska B. and Lawrence I. 2002. A comparison of catchment water quality models and direct estimation techniques. Environmental Modelling and Software 17 (1), 77-85.

Mastrocicco M., Colombani N., Salemi E. and Castaldelli G. 2011. Reactive modelling of denitrification in soils with natural and depleted organic matter. Water Air and Soil Pollution 222, 205-215.

Mastrocicco M., Colombani N., Salemi E., Vincenzi F. and Castaldelli G. 2012. The role of the unsaturated zone in determining nitrate leaching to groundwater, In: Zuber A., Maloszewski P., Witczak S. and Malina G. (eds), Groundwater Quality Sustainability, IAH Book Series, Taylor & Francis Books (UK), in press.

Oenema O., Kros H. and de Vries W. 2003. Approaches and uncertainties in nutrient budgets: implications for nutrient management and environmental policies, European Journal of Agronomy 20 (1–2), 3-16.

Soana E., Racchetti E., Laini A., Bartoli M. and Viaroli P. 2011. Soil Budget, Net Export, and Potential Sinks of Nitrogen in the Lower Oglio River Watershed (Northern Italy). CLEAN – Soil, Air, Water 39 (11), 956-965.

Nitrogen Workshop 2012

Nitrogen mineralization potential of soil amended with biochar from pig-slurry solids Marchetti, R.a, Castelli, F.b, Orsi, A.a, Sghedoni, L.a a Agricultural Research Council, Research unit for swine husbandry, San Cesario sul Panaro (MO), Italy b Agricultural Research Council, Bovolone Experimental Farm, Bovolone (VR), Italy

1. Background & Objectives Interest in biochar (BC) has dramatically grown in recent years, due mainly to the fact that its incorporation into soil reportedly enhances carbon sequestration and fertility (Lehmann and Joseph, 2009). As large amounts of livestock manure solids are expected to become available in the near future, due to the development of technologies for the separation of the solid fraction of animal effluents (Burton, 2007), the processing of manure solids for BC production seems an interesting possibility for the recycling of OM of high nutrient value. The aim of this study was to estimate the nitrogen (N) mineralization potential (NMP) of soil amended with BC from pig-slurry solids. Wood chip, which is currently used as a raw source for BC production, was also included in the comparison as reference material. To test the hypothesis that BC can retain N when incorporated into soil we also applied fresh digestate (D) derived from a biogas plant to soil as a N source, and the BCD interaction effect on soil NMP was evaluated.

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3. Results & Discussion Time courses of NMP in soil after OM incorporation are reported in Figure 1. Without digestate addition (Figure 1a) in soil amended with non-charred OM (CC and LC treatments) NMP decreased during the first two weeks of incubation. The NMP values increased again to the control levels in the following two months, in LC, whereas in CC values remained significantly lower than in the control (after 90 d, 32.84 mg kg-1, S.E.= 4.64 mg kg-1). In soil amended with charred OM (CT and LT treatments) only slight fluctuations of NMP around 0 were detected (i.e. no changes

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-1

-1

-20

-20

-40

-40

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4. Conclusion The charring of OM affected the pattern of release of mineral N in soil in the short term, apparently reducing the MIT intensity, compared with that associated with non-charred OM. Nitrogen availability, clearly modified after soil amendment with non-charred OM, did not seem to be affected by incorporation of BC, either of plant or animal origin. Biochar incorporation did not reduce N availability in soil supplied with digestate, the pattern of interaction between soil amendments and digestate being instead influenced by the type of amendment.

Acknowledgements: This work was granted by MiPAAF within the framework of the project "Development of models for husbandry sustainability" (SOS ZOOT), MAREA sub-project.

References Lehmann J. and Joseph S. 2009. Biochar for environmental management: science and technology, Earthscan, London, GB.

Burton C.H. 2007. The potential contribution of separation technologies to the management of livestock manure.

Livestock Science 112, 208-216.

Drinkwater L.E., Cambardella C.A., Reeder J.D. and Rice C.W. 1996. Potentially mineralizable nitrogen as an indicator of biologically active soil nitrogen, In: Doran J.W.and Jones A.J. (eds.), Methods for assessing soil quality, SSSA Spec.

Publ. 49, Madison, WI, USA pp. 217-229.

Paul E.A. and Clark F.E. 1996. Soil Microbiology and Biochemistry (2nd edition), Academic Press, San Diego, CA.

Nitrogen Workshop 2012

Nitrogen mineralization potentials in rice-wheat systems in southeastern China Hofmeier, M.a, Roelcke, M.a, Yong, H.b, Cai, Z.C.c, Nieder, R. a a Institute of Geoecology, TU Braunschweig, 38106 Braunschweig, Germany b Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, P.R. China c College of Geography Science, Nanjing Normal University, Nanjing 210046, P.R. China

1. Background & Objectives Th erice (Oryza sativa L.)-wheat (Triticum aestivum L.) double-cropping system in southeastern China is characterized by anaerobic conditions during the irrigated lowland summer rice crop and aerobic conditions during the upland winter wheat crop. However, the alternating water regime leads to high gaseous and leaching losses of nitrogen (N) mainly after the winter wheat crop due to flooding, puddling and ponding of the field for the summer rice crop (Roelcke et al., 2002). In order to minimize these losses, little residual mineral N (Nmin) should be present in the soil profile at wheat harvest. Mineral N fertilizer application needs to be optimized and adapted to the demand of the winter wheat crop. Therefore, a better understanding of the N transformation processes, including mineralization dynamics of organic N during the winter wheat cropping season is essential. Long-term aerobic incubation laboratory experiments were carried out with soils from two rice-wheat growing regions in southeastern China.



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