Controlling nitrogen flows and losses

"This book is a synthesis of contributions drawn from the 12th Nitrogen Workshop held at the University of Exeter, UK. It provides a valuable compilation of current research, aimed at reconciling the environmental and economic components of N cycling within the context of a productive agricultural industry. The book is divided into seven main sections, which examine systematically, the nature of the problems associated with losses of N and a range of possible solutions. Section 1, ‘Drivers towards sustainability-why change?’ identifies the need to adopt new strategies to avoid losses to the environment. Section 2 considers the options for ‘Matching supply with demand’, followed by the reasons for, and means of ‘Controlling losses to air’ and to ‘water’ in section 3 and 4. Section 5 describes the challenges of ‘Reconciling productivity with environmental considerations’. The remaining sections describe some mathematical models to assist the researcher, with the final section devoted to reports from the ‘Themed Working Groups’ which debated the following topical questions: Organic matter: does it matter, or can technology overcome most problems related to soil fertility? Optimising N additions: can we integrate fertilizer use and manure use? Controlling gaseous N emissions: what is achievable? Missing N: is the solution in dissolved N? Pollution problems: mitigation, or are we swapping one form of pollution for another? System studies: do we need them, or can they be replaced by desktop studies? Model answers: can we improve their level of confidence and applicability? This book will be of value to researchers, policy makers and all those wishing to promote more efficient use of N."

Table of Contents:
Preface 7; Section 1 - Drivers towards sustainability: why change? 27; Drivers towards sustainability: why change? 29; J.J. Neeteson, J.J. Schroder and C. Jakobsson; Nitrogen balances over seven years on a mixed farm in the Cotswolds 39; K.A. Leach, K.W.T. Goulding, D.J. Hatch, J.S. Conway and K.D. Allingham; Watershed nitrogen modelling 47; N.J. Hutchings, T. Dalgaard, B.M. Rasmussen, J.F. Hansen, M. Dahl, P. Rasmussen, L.F. Jorgensen, V. Ernstsen, F. von Platen-Hallermund and S.S. Pedersen; Mitigating non-point source pollution from dairy farms: Economic evaluation on the Don watershed 54; N. Turpin, G. Rotillon, P. Bontems, T. Bioteau and R. Laplana; Relationships between fertiliser nitrogen additions, crop carbon returns and soil quality 63; A. Bhogal, B.J. Chambers and F.A. Nicholson; Fluxes of nitrogen following clearing of Brazilian Amazonian tropical forest for pasture 65; M.C. Piccolo, C. Neill, C.C. Cerri and J.M. Melillo; Nitrogen losses from forage legumes and effects on succeeding cereal crops in organic farming under pannonic climate conditions in Eastern Austria 67; R. Farthofer, J.K. Friedel, G. Pietsch, W. Loiskandl and B. Freyer; Your farm and NVZs: A decision support system for farmers and consultants 70; C.P. Fawcett, M.M. Gibbons, F.A. Brown, P.M.R. Dampney and S.J. Richardson; Fate of applied nitrogen in a heathland ecosystem 73; E.R. Green, S.A. Power and E.M. Baggs; Effects of intensification of dairy farming in New Zealand on nitrogen efficiency, energy use and environmental emissions 76; S.F. Ledgard, J.D. Finlayson, M.S. Sprosen, D.M. Wheeler and N.A. Jollands. Effect of groundnut stover and weed management methods in the dry season on N cycling and maize yield 78; S. Promsakha na sakonnakhon, B. Toomsan, V. Limpinuntana, P. Vityakon, E.M. Baggs and G. Cadisch; Development of a decision support tool for global diffuse nitrogen pollution assessment 81; C. Macleod, J. Dela-Cruz, P. Haygarth, G. Glegg, D. Scholefield and L. Mee; Organic fertilisation in silvopastoralism and nitrate losses: sustainable systems 83; M.R. Mosquera-Losada, S. Rodriguez-Barreira and A. Rigueiro-Rodriguez; How nitrate vulnerable zones can reduce the adverse environmental impact of productive arable agriculture 85; J.U. Smith, P. Smith, A.G. Dailey and M.J. Glendining; Decline in species richness in acid grasslands along a gradient of nitrogen deposition 88; C.J. Stevens, N.B. Dise, D.J. Gowing and J.O. Mountford; Development of a modelling system for prediction and regulation of livestock waste pollution in the humid tropics 90; T.P. Tee, I.J. Lean, E.M. Baggs and G. Cadisch; The agricultural area survey as a tool for implementing the European Nitrates Directive in the Walloon Region of Belgium 93; C. Vandenberghe, A.C. Mohimont, T. Garot and J.M. Marcoen; Environmental economics of soil organic matter management 96; N. Wrage and O. Oenema; Section 2 - Matching supply with demand 99; Matching supply with demand 101; D.V. Murphy, E.A. Stockdale, F.C. Hoyle, J.U. Smith, I.R.P. Fillery, N. Milton, W.R. Cookson, L. Brussaard and D.L. Jones; Can N mineralisation be predicted from soil organic matter? Carbon and gross N mineralisation rates as affected by long-term additions of different organic amendments 113; A. Herrmann, E. Witter and T. Katterer; N mineralisation from decomposition of catch crop residues under field conditions: measurement and simulation using the STICS soil-crop model 122; E. Justes and B. Mary. Gross N transformation rates and soil organic matter contents in grassland soils of different age 131; F. Accoe, P. Boeckx, O. Van Cleemput and G. Hofman; The relative efficiency of fertiliser N in NK blends and concentrated complex fertilisers 133; N.A. Akhonzada and J.S. Bailey; Nitrogen mineralisation from fish sludge as affected by plant uptake 136; M.A. Alfaro, F.J. Salazar and A. Valdebenito; Modelling of N-cycle for processes in soil using soil core experiments 138; A. Balint, Cs. Meszaros, Gy. Heltai, E. Notas and K. Jung; Mineralisation of nitrogen in relation to climatic variation and soil 140; H. Bjornsson; Resolving differences in N cycling between more polluted and pristine forests using 15N isotope dilution 143; P. Boeckx, R. Godoy, C. Oyarzun, J. Bot and O. Van Cleemput; Effects of tillage and crop rotation on the microbial population and dynamics of soil organic matter 145; C. Carranca, A. Oliveira, A. de Varennes, M. Pampulha, M. Costa, A. Prazeres, J. Baeta, C. Neto, M.P. Andrada and M.O. Torres; The changes in microbial biomass nitrogen when different rates and forms of N were applied in a long-term experiment with maize 148; J. Cerny and J. Balik; Screening of organic biological waste products for their potential to manipulate the N release from crop residues 151; B. Chaves, S. De Neve, G. Hofman, P. Boeckx and O. Van Cleemput; Nitrogen dynamics in soil with mulch and incorporated crop residues 153; F. Coppens, S. Recous, P. Garnier and R. Merckx; Prediction of nitrogen mineralisation from organic residues and supply to ryegrass 156; C.M.d.S. Cordovil, J. Coutinho and F. Cabral; Reliability of a chemical method to assess nitrogen uptake by winter wheat 158; C.M.d.S. Cordovil, J. Coutinho and F. Cabral; Rhizodeposition and symbiotic N2 fixation in trimmed and untrimmed white clover 160; S. Dahlin. Within-field variations in, and relations between, grain protein content, grain yield and plant-available soil nitrogen 162; S. Delin; The turnover of organic manure using natural 13C abundance 164; K. Dittert and R. Bol; Nitrification during autumn and winter of ammonium nitrogen in cattle slurry applied to soil at different times during the autumn 166; L. Engstrom, B. Linden and L. Ericsson; Effect of rate of cattle slurry at sowing, number of fertigations with separated slurry liquid and rate of mineral N top dressings on yield and N removal by forage maize 168; A. Fernandes, H. Trindade, J. Coutinho and N. Moreira; N balance in fertilizer trials with composted municipal solid wastes in southern Italy 171; D. Ferri, G. Convertini and F. Montemurro; How to enhance crop utilisation of deep subsoil nitrogen supply 173; J. Haberle, P. Svoboda and J. Krejcova; Model SFOM - the first step towards fertiliser and manure use integration 176; T. Jadczyszyn; Straw-rich deep litter manures - can decomposition and N turnover be predicted from quality? 179; L.S. Jensen, A. Jensen and A. Pedersen; Field experiments to determine N accumulation under fertility building crops 182; A. Joynes, D.J. Hatch, A. Stone, S. Cuttle, G. Goodlass and S. Roderick; A comparison of different indices for nitrogen mineralisation 184; A. Kokkonen and M. Esala; A novel approach to regulate nitrogen mineralisation in soil 186; K. Kumar, C.J. Rosen and M.P. Russelle; Variable nitrogen fertilisation by tractor-mounted remote sensing 188; A. Link, J. Jasper and H.-W. Olfs; A dynamic version of the predictive balance sheet method for fertiliser N advice 191; J.M. Machet, S. Recous, M.H. Jeuffroy, B. Mary, B. Nicolardot and V. Parnaudeau. Residual effects of maize nitrogen fertilisation on winter barley crop: N content, yield, yield components and agronomic factors 194; M. Maiorana, F. Montemurro, G. Convertini and F. Fornaro; Turnover of grain legume N rhizodeposits and effect of rhizodeposition on the turnover of crop residues 197; J. Mayer, F. Buegger, E.S. Jensen, M. Schloter and J. Hess; Decomposition of soluble compounds obtained after fractionation of different animal wastes 200; T. Morvan and B. Nicolardot; Is good nutrient management possible by applying more than 170 kg nitrogen per hectare from manure? 203; A. Mulier, G. Hofman and I. Verbruggen; Regulation of N release from polyphenol-protein complexes by fungi in different tropical production systems 205; R. Mutabaruka and G. Cadisch; Modelling nitrogen mineralisation from mature bio-waste compost applied to vineyard soils 207; C. Nendel, S. Reuter, K.C. Kersebaum, R. Nieder and R. Kubiak; Inorganic N dynamics in vineyard soils under different covering strategies 209; B. Nicolardot, P. Thiebeau, C. Herre, A.F. Doledec, A. Perraud and B. Mary; Effect of rate and timing of nitrogen fertiliser on yield and grain protein content in winter wheat. The chlorophyll meter as a nutritional diagnostic tool 212; M.A. Ortuzar, A. Alonso, A. Aizpurua, A. Castellon and J.M Estavillo; Assessing N dynamics of organic wastes in field conditions using a calculation model 214; V. Parnaudeau, P. Robert, C. Herre, F. Millon, B. Mary and B. Nicolardot; 15N labelling and use of dairy manure components for N cycling studies 217; J.M. Powell and K.A. Kelling; Predicting soil mineral nitrogen in spring, based on soil mineralisable N in autumn 219; M. Quemada; Effect of seasonal split of N dosage on the fate of 15N fate in citrus trees 222; A. Quinones, J. Banuls, E. Primo-Millo and F. Legaz. Methodology of soil incubation studies -comparison between laboratories 224; T. Salo, L.S. Jensen, F. Palmason, T.A. Breland, B. Stenberg, A. Pedersen, C. Lundstrom and M. Esala; Attempts to overcome genotypic variability of SPAD readings in winter triticale 226; S. Samborski and J. Rozbicki; Organic nitrogen loads at different scale levels in Spain 229; J. Soler-Rovira and J.M. Arroyo-Sanz; Organic nutrient management indicators at district level in Spain 231; J. Soler-Rovira and J.M. Arroyo-Sanz; Physical separation of pig slurry has a small effect on the overall utilisation of nitrogen 234; P. Sorensen, I.K. Thomsen and B.T. Christensen; The use of anaerobic incubations to predict net N immobilisation after the application of organic residues to soils 236; J.R. Sousa, R. Lagoa, F. Cabral and J. Coutinho; Nitrogen uptake by ryegrass (Lolium perenne) as affected by the decomposition of apple leaves and pruning wood in soil 239; M. Tagliavini, G. Tonon, D. Solimando, P. Gioacchini, M. Toselli, P. Boldreghini and C. Ciavatta; Use of the NDICEA model analysing nitrogen efficiency 242; G.J. van der Burgt; Microbial biomass measurements in soil of the central highlands of Mexico 244; M.S. Vasquez-Murrieta and L. Dendooven; Natural 15N abundance as an indicator of the effect of management intensity on nitrogen cycling in montane grasslands 246; M. Watzka and W. Wanek; Section 3 - Controlling losses to air 249; Controlling losses to air 251; E.A. Davidson and A.R. Mosier; Pitfalls in measuring nitrous oxide production by nitrifiers 260; N. Wrage, G.L. Velthof, H.L. Laanbroek and O. Oenema. The effect of organic and mineral nitrogen fertilisers on emissions of NO, N2O and CH4 from cut grassland 268; R. Rees, S. Jones, R.E. Thorman, I. McTaggart, B. Ball and U. Skiba; A new agricultural ammonia emission inventory for Switzerland based on a large scale survey and model calculations 277; B. Reidy, S. Pfefferli and H. Menzi; N2O emissions from a field trial as influenced by N fertilisation and nitrification inhibitors 285; D. Baez, J. Coutinho, N. Moreira and H. Trindade; Denitrification and interactions between nitrification and methane oxidation under elevated atmospheric CO2 288; E.M. Baggs, H. Blum, M. Richter, G. Cadisch and U.A. Hartwig; Soil water content as a factor that controls N2O production by denitrification and autotrophic and heterotrophic nitrification 290; E.J. Bateman, G. Cadisch and E.M. Baggs; Short-term CO2 and N2O emission after application of manure and maize residues to three different soil types: a laboratory study 293; D. Beheydt, P. Boeckx, L. Geers, A. Goossens and O. Van Cleemput; Influence of urinary N concentration on N2O and CO2 emissions and N transformation in a temperate grassland soil 295; R. Bol, S.O. Petersen, K. Dittert and M.N. Hansen; A model-based evaluation of options for the mitigation of agricultural nitrous oxide emission 298; L. Brown, L. Cardenas, P. Bellamy, S.C. Jarvis, J. Hollis, R.W. Sneath, S. Yamulki and K.W.T. Goulding; Variations in aerobic respiratory and denitrifying activities in the vadose zone: laboratory and field experiments 300; P. Cannavo, F. Lafolie, A. Richaume, B. Nicolardot and P. Renault; Use of a 2-pool model to evaluate the effect of fertiliser application on nitrogen emissions from grassland soils 303; L.M. Cardenas, J.M.B. Hawkins, D. Chadwick and D. Scholefield; Opportunities for reducing ammonia emissions from pig housing in the UK 306; T.G.M. Demmers, R. Kay and N. Teer; A comparison of nitrous oxide and ammonia fluxes from managed grassland 309; C.Di Marco, M. Anderson, C. Milford, U. Skiba, M.A. Sutton and K. Weston. Gaseous losses of various nitrogeneous compounds from fertilisation of a wheat crop 311; S. Genermont, C. Henault, P. Laville, M.H. Jeuffroy and D. Flura; A simple denitrification model? Review, sensitivity and application 314; M. Heinen; Nitrous oxide emissions from soil - fertiliser and soil type effects 316; B. Hyde, A. Fanning, M. Ryan, M. Hawkins and O.T. Carton; The Irish ammonia emission inventory - implications for compliance with the Gothenburg Protocol 318; B.P. Hyde, T. Misslebrook and O.T. Carton; Greenhouse gas emissions in meadow mesocosms exposed to elevated O3 and CO2 321; T. Kanerva, K. Koivisto,K. Karhu, K. Regina and S. Manninen; Refining the uncertainty in nitrous oxide emissions from New Zealand agricultural soils 323; F.M. Kelliher, A.S. Walcroft, S.F. Ledgard, H. Clark, G. Rys, H. Plume, M. Buchan and R.R. Sherlock; Dynamics of N2O and NO production by Alcaligenes faecalis parafaecalis: effect of pH, temperature, substrate and oxygen supply 326; M. Kesik, S. Blagodatsky, H. Papen and K. Butterbach-Bahl; Denitrification and nitrate loss from organic agricultural soil at low temperatures 329; H.T. Koponen, A. Parna, H. Silvennoinen and P.J. Martikainen; N2O emissions from a water-saving rice production system (GCRPS) in North China 331; C. Kreye, K. Dittert, X. Zheng, X. Zhang, S. Lin, H. Tao and B. Sattelmacher; Controlling nitrous oxide emissions from agriculture: experience from The Netherlands 333; P.J. Kuikman, G.L. Velthof and O. Oenema; Fluxes of N2O from permanent grassland with different levels of nitrogen supply 336; C. Lampe, F. Taube, M. Wachendorf, B. Sattelmacher and K. Dittert; Gaseous nitrogen emissions from effluent irrigated soils 338; Y. Master, R.J. Stevens, R.J. Laughlin, U. Shavit and A. Shaviv; Reducing losses of nitrous oxide from cattle slurry and mineral fertiliser applied to grassland by the use of DMPP 340; P. Merino, A. del Prado, S. Menendez, L. Careaga, M. Pinto, J.M. Estavillo and C. Gonzalez-Murua. Influence of white clover on nitrous oxide fluxes in grassland 342; A. Mori, M. Hojito, H. Kondo, H. Matsunami and D. Scholefield; The effect of agricultural ammonia deposition on nitrous oxide production by soils under coniferous and deciduous woodland cover. 345; T. Morrissey, P. Ineson and D.R. Chadwick; Determination of N source in denitrification studies using stable isotope techniques 347; P.J. Murray, D.J. Hatch, E.R. Dixon, R.J. Stevens, R.J. Laughlin, K. O'Prey and S.C. Jarvis; Using a system of undisturbed, in situ soil lysimeters to determine nitrogen transformations in a sub-surface clay interface 349; P.J. Murray, E.R. Dixon, S.J. Granger, D.J. Hatch, S.C. Jarvis, R.J. Laughlin and R.J. Stevens; Urea concentration affects short-term N turnover and N2O production in grassland soil 351; S.O. Petersen, S. Stamatiadis, C. Christofides, S. Yamulki and R. Bol; Leached N and the nitrous oxide emission factor 354; D.S. Reay, K.A. Smith and A.C. Edwards; Seasonal subsoil denitrification of leached 15N-labelled nitrate 357; S.M. Thomas, T.J. Clough, G.S. Francis, D.I. Hedderley, R.R. Sherlock and M.H. Beare; N2O emissions from intensive vegetable production systems 359; S.M. Thomas, H.E. Barlow, G.S. Francis and D.I. Hedderley; Improving New Zealand predictions of N leaching for estimating indirect N2O emissions 361; S.M. Thomas, S.F. Ledgard and G.S. Francis; Nitrogen losses during storage and following the land spreading of poultry manure 363; R.E. Thorman, B.J. Chambers, R. Harrison, D.R. Chadwick, R. Matthews and R.J. Nicholson; From N2 fixation to N2O emission in a grass-clover mixture 365; M. Thyme and P. Ambus; Nitrous oxide emission from an irrigated soil fertilised with pig slurry in Central Spain 367; A. Vallejo, J.A. Diez, L. Garcia-Torres, P. Hernaiz and S. Lopez-Fernandez. Can tillage practice affect the contribution of nitrous oxide to the total greenhouse gas production from arable agriculture? 369; C.P. Webster, T.S. Scott and K.W.T. Goulding; Soils as sources of N-trace gases in Germany - results from calculations with biogeochemical models 372; C. Werner, M. Kesik, H. Papen, C. Li and K. Butterbach-Bahl; Denitrification in top soil and sub soil, data and model results 375; K.B. Zwart; Section 4 - Controlling losses to water 379; Controlling losses to water 381; M.A. Shepherd and E.I. Lord; Nitrate leaching from arable crop rotations in organic farming 389; J.E. Olesen, M. Askegaard and J. Berntsen; Nitrogen rate, surplus or residue? Performance of selected indicators for nitrate leaching 397; H.F.M. ten Berge, S.L.G.E. Burgers, M.J.D. Hack-ten Broeke, A. Smit, J.J. de Gruijter, G.L. Velthof, J.J. Schroder, J. Oenema, F.J. de Ruijter, S. Radersma, I.E. Hoving and D. Boels; Safety-nets and filter functions of tropical agroforestry systems 406; G. Cadisch, E. Rowe, D. Suprayogo and M. van Noordwijk; Comparison of the efficiency of different catch crops on potentially leachable nitrate 415; P.Y. Bontemps, R. Lambert, C. Devillers and A. Peeters; Inverse stochastic modelling of water and N drainage from lysimeters 417; M. Decrem, K.C. Abbaspour, J. Nievergelt, F. Herzog and W. Richner; Nitrogen concentrations in an intensively farmed livestock catchment 420; O. del Hierro, M. Pinto, A. Artetxe and A. del Prado; NGAUGE DSS as a tool to assist UK dairy farmers to comply with EU nitrate legislation 423; A. del Prado, L. Brown and D. Scholefield; Comparison between the risk of nitrogen leaching from temporary cut grassland and maize 425; B. Deprez, D. Knoden, H. de Blander, R. Lambert, C. Decamps and A. Peeters. Temporal and spatial denitrification patterns in nitrate retention by three riparian buffer zones 428; K. Dhondt, P. Boeckx, O. Van Cleemput and G. Hofman; Effective reductions in nitrate leaching and nitrous oxide emissions by the use of a nitrification inhibitor, dicyandiamide (DCD), in a grazed and irrigated grassland 431; H.J. Di and K.C. Cameron; Nitrate leaching and N2-fixation in grasslands of different composition, age and management 434; J. Eriksen and F.P. Vinther; Action programme and practices for reduction of nitrate from agricultural sources in Central Greece 437; T. Georgiou, T. Karyotis, I. Katsilouli, A. Haroulis, M. Toulios and G. Argyropoulos; A field study of nitrate leaching from tillage crops in Ireland 439; K.V. Hooker, K. Richards, C.E. Coxonand R. Hackett; Dissolved organic nitrogen concentration in two grassland soils 441; D.L. Jones, J.F. Farrar and V.B. Willett; Simulation with STICS soil-crop model of catch crop effects on nitrate leaching during the fallow period and on N released for the succeeding main crop 444; E. Justes, F. Dorsainvil, M. Alexandre and P. Thiebeau; Nitrate in soils and water originated from agricultural sources: a case study in Thessaly, Central Greece 447; Ir. Katsilouli, Th. Karyotis, Th. Georgiou, Th. Mitsimponas, A. Panagopoulos, A. Panoras, D. Pateras, A. Haroulis, G. Argyropoulos and M. Toulios; Monitoring and mathematical modelling of nitrate leaching in an experimental field treated with pig slurry 449; P. Mantovi, L. Fumagalli and G.P. Beretta; Nitrate leaching in arable cropland: effects of N-management 452; A. Smit and K.B. Zwart; Reducing nitrate contamination of groundwater from intensive greenhouse-based vegetable production in Almeria, Spain - management considerations 454; R.B. Thompson, M. Gallardo and C. Gimenez; Nitrogen budgets at field, farm and polder scales in a polder used for dairy farming 457; C.L. van Beek, G.L. Velthof and O. Oenema. Nitrate leaching on loess soils as affected by N fertilisation and crop rotation 459; W. van Dijk, P. Dekker and J.R. van der Schoot; Loss of inorganic nitrogen in surface runoff from grazed grassland 461; C.J. Watson, R.V. Smith and E. Chisholm; Nitrogen losses in drainage water following pig slurry applications to an arable clay soil 463; J.R. Williams, B.J. Chambers R.B. Cross and R.A. Hodgkinson; Section 5 - Reconciling productivity with environmental considerations 467; Reconciling productivity with environmental considerations 469; D. Scholefield; Forage maize production as affected by tillage, N source and nitrification inhibitors 484; D. Baez, J. Coutinho, N. Moreira and H. Trindade; Is the N balance a good indicator of nitrogen losses in arable systems? 487; N. Beaudoin, B. Mary, F. Laurent, G. Aubrion and J.K. Saad; A low disturbance technique for applying slurry on forage land 490; S. Bittman, L.J.P. van Vliet, C.G. Kowalenko, S. McGinn, A.K. Lau, N. Patni, T. Forge, N. McLaughlin, D.E. Hunt, F. Bounaix and A. Friesen; Effects of field history on the establishment of white clover in association with perennial ryegrass 493; L.M. Bommele, D. Reheul, N. Van Eekeren and F. Nevens; Nitrogen losses in relation to rice varieties, growth stages, and nitrogen forms determined with the 15N technique 496; N.C. Chen and S. Inanaga; Effectiveness of alternative managements to reduce N losses from dairy farms 498; S.P. Cuttle and M.M. Turner; Azofert: a new decision support tool for fertiliser N recommendations 500; P. Dubrulle, J.M. Machet and N. Damay; Compost use in vegetable production: impact on gross N fluxes and implications for sustainable management practices 502; T.C. Flavel and D.V. Murphy. Ammonia volatilisation and soil nitrogen dynamics following application of pig deep-litter and pig slurry in different soil tillage systems 504; S.J. Giacomini, C. Aita, E. Guidini, E.B. Amaral and A. Lunkes; Estimation of nitrogen loading in Japanese prefectures and scenario testing of abatement strategies 507; M. Hojito, A. Ikeguchi, K. Kohyama, K. Shimada, A. Ogino, S. Mishima and K. Kaku; Indicators for environmental and economic sustainability on UK dairy farms 510; E.C. Jewkes, D. Scholefield, M.M. Turner and L. Brown; Dairy production using an extended grazing management system - a preliminary assessment of nitrogen flows 513; E.C. Jewkes, D. Scholefield, M.R. Butler, J. Webb, T. Forrester, J. Lapworth, K. Russell, G. Bailey, A. Lathwood and A. Clarke; Decrease in the amount of residual nitrate in cultivated land 516; R. Lambert, V. Van Bol and A. Peeters; Estimating nitrogen losses from animal manures using their phosphorus balance 518; R. Lambert, B. Toussaint and A. Peeters; Encouraging farmers to utilise nitrogen more efficiently 520; K.A. Leach, J.S. Conway, J.P. Morgan, B.F. Pain and D. Munday; Conserving biologically fixed N to increase its utilisation and decrease gaseous losses 523; A.K. Loes, A.K. Bakken, T.A. Breland, R. Eltun and H. Riley; Effect of animal treading intensity on the efficiency of N2 fixation by clover in mixed grass/clover pasture and potential implications for long-term soil N availability 525; J.C. Menneer, S.F. Ledgard, C.D.A McLay and W.B. Silvester; Effect of type and dose of sewage sludge application in maize+ryegrass rotation in Galicia (NW Spain) 527; M.R. Mosquera-Losada, A. Amador-Garcia and A. Rigueiro-Rodriguez; Cattle slurry and vegetable, fruit and garden (VFG) waste compost in silage maize: fertiliser N no longer needed? 530; F. Nevens and D. Reheul; Applying a ley/arable rotation to reduce N input in forages 532; F. Nevens and D. Reheul; Farm N budgets with estimated nitrogen losses by use of soil N modelling 534; A.H. Nielsen, B.M. Petersen and I.S. Kristensen. Political transformations and nitrogen balances of dairy farms in Poland 536; S. Pietrzak and O. Oenema; Dirty water - a valuable source of nitrogen on dairy farms 539; K. Richards, M. Ryan and C.E. Coxon; Effect of date and dose of sewage sludge application in grasslands production and nitrogen soil concentration in Galicia (NW Spain) 541; A. Rigueiro-Rodriguez, A. Casanova-Vigo and M.R. Mosquera-Losada; Nitrate losses in forestry nurseries using municipal sewage sludge 544; A. Rigueiro-Rodriguez, J. Rasche-Castillo and M.R. Mosquera-Losada; Assessment of measures to reduce nitrogen losses from dairy farms 547; J. Scheringer and J. Isselstein; Nitrogen use efficiency in a water saving ground cover rice production system in Beijing, North China 549; H. Tao, K. Dittert, S. Lin, C. Kreye and B. Sattelmacher; Effect of herbicide, maize variety precocity and sowing date of three winter cover crops on forage yield and on herbage N removal from an intensive double-cropping system 551; H. Trindade, J. Coutinho and N. Moreira; Effects of grassland renovation on herbage yields and nitrogen losses 554; G.L. Velthof and I.E. Hoving; Nitrogen budgets of Flemish specialised dairy farms during 1990-2000 557; I. Verbruggen, F. Nevens, A. Mulier and G. Hofman; Substitution of N fertiliser supply for maize with lupin as a winter crop in rotations under zero and conventional tillage in southern Brazil 559; L. Zotarelli, B.J.R. Alves, E. Torres, S. Urquiaga and R.M. Boddey; Section 6 - Models and decision support systems 563; NGAUGE: A decision support system to optimise N fertilisation of UK grassland for economic and/or environmental goals 565; L. Brown, D. Scholefield, E.C. Jewkes, A. del Prado and D.R. Lockyer; UK-DNDC: a mechanistic model to estimate N2O fluxes in the UK 567; L. Brown, B. Syed, S.C. Jarvis, R.W. Sneath, V.R. Phillips, K.W.T. Goulding and C. Li. MAST - a model of ammonia volatilisation with an examination of abatement strategies for a dairy farm 569; E.C. Jewkes, C.A. Ross, D. Scholefield and S.C. Jarvis; Development of the OVERSEER[registered] nutrient budget model to examine implications of pastoral management practices on nitrogen flows and losses 571; S.F. Ledgard, D.M. Wheeler, C.A.M. de Klein, R.M. Monaghan and K. Johns; The MANNER model: predicting the crop available N supply from farm manure applications 573; F.A. Nicholson, B.J. Chambers, E.I. Lord, K.A. Smith, S.A. Anthony and M.M. Gibbons; The nutrient leaching model ANIMO 575; J. Roelsma, P. Groenendijk and O.F. Schoumans; The SUNDIAL Model 577; J.U. Smith, P. Smith, A.G. Dailey, M.J. Glendining, G. Tuck and P.K. Leech; Section 7 - Themed working groups 579; Organic matter: does it matter, or can technology overcome most problems related to soil fertility? 581; Report by S. Recous and G. Cadisch; Optimising N additions: can we integrate fertiliser and manure use? 586; Report by J.J. Schroder and R.J. Stevens; Controlling gaseous N emissions - what is achievable? 594; Report by R. Harrison and E.M. Baggs; Missing N: is the solution in dissolved N? 600; Report by A.J. Macdonald and D.L. Jones; Pollution problems: mitigation or are we swapping one form of pollution for another? 606; Report by B.J. Chambers and O. Oenema; Systems studies; do we need them, or can they be replaced by desktop studies? 609; Report by H.F.M. Aarts and A. Pflimlin; Model answers: can we improve their level of confidence and applicability? 615; Report by S.F. Ledgard and N.J. Hutchings; Author index 619.