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Nitrogen and sulphur fertilization effect on leaching losses, nutrient balance and plant quality in a wheat–rapeseed rotation under a humid Mediterranean climate

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Abstract

An unbalanced S and/or N fertilization may have low N and S use efficiency together with substantial negative implications for yield, nutrient losses and plant quality parameters. The effect of N and S fertilization and their interactions on N–S balances, on N–S losses and on some plant quality parameters were investigated in a field experiment with a wheat (Triticum aestivum L.)–rapeseed (Brassica napus L.)–wheat rotation (2005–2008). The study was conducted under humid Mediterranean climatic conditions on a potentially S deficient soil. The effects of N (0, 140, 180, 220 kg N ha−1 in wheat; 0, 100, 140, 180, 220 N ha−1 in rapeseed) combined with S fertilizer rates (0, 16 and 32 kg S ha−1 in wheat and 0, 30, 60 kg S ha−1 in rapeseed) were studied. Nitrogen fertilization increased yield by 55 % in wheat and 60 % in rapeseed, N concentration in grain and straw and S concentration in the grain of wheat. However, it led to a reduction in the S concentration of straw and the oil content of the rapeseed seed. The S application did not increase yield but had a positive effect on S concentration in the wheat straw. Glucosinolate concentration, a potentially toxic secondary metabolite in rapeseed, was not influenced by N or S applications. Nitrate leaching tended to increase with N application while sulphate leaching decreased. A net N and S mineralization was observed in each growing season, except for the first year in which a net S immobilization was observed. To make N fertilizer recommendations, the N mineralization from the previous crop residues should be taken into account. For S fertilizer recommendations, N supply is the most important item both from a qualitative point of view (N/S ratio in wheat grain) and an environmental point of view (S leaching).

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References

  • Abad A, Lloveras J, Michelena A (2004) Nitrogen fertilization and foliar urea effects on durum wheat yield and quality and on residual soil nitrate in irrigated Mediterranean conditions. Field Crop Res 87:257–269

    Article  Google Scholar 

  • Ahmad G, Jan A, Arif M, Jan MT, Khattak RA (2007) Influence of nitrogen and sulfur fertilization on quality of canola (Brassica napus L.) under rainfed conditions. J Zhejiang Univ Sci B 8(10):731–737

    Article  PubMed  CAS  Google Scholar 

  • Aizpurua A, Estavillo JM, Castellón A, Alonso A, Besga G, Ortuzar-Iragorri MA (2010) Estimation of optimum nitrogen fertilizer rates in winter wheat in humid Mediterranean conditions, II: economically optimal dose of nitrogen. Commun Soil Sci Plant Anal 41(3):301–307

    Article  Google Scholar 

  • Alcoz MM, Hons FM, Haby VA (1993) Nitrogen fertilization timing effect on wheat production, nitrogen uptake efficiency, and residual soil nitrogen. Agron J 85:1198–1203

    Article  Google Scholar 

  • Allen RG, Pereira LS, Raes D, Smith M (1998) Crop evapotranspiration-guidelines for computing crop water requirements-FAO irrigation and drainage paper 56. Water Resources, Development and Management Service

  • Alley MM, Scharf P, Brann DE, Baethgen WE, Hammons JL (2009) Nitrogen management for winter wheat: principles and recommendations. Virginia Cooperative Extension Publication, 424-026

  • Alpkem (1986) Nitrate + nitrite nitrogen (A303-S170). RFA methodology. Alpkem Corporation, Clackamas, pp 1–10

    Google Scholar 

  • Alpkem (1987) Ammonia nitrogen (A303-S020). RFA methodology. Alpkem Corporation, Clackamas, pp 1–7

    Google Scholar 

  • AOAC, Association of Official Analytical Chemists International (1999) Plants. In: Cunniff P (ed) Official methods of analysis of AOAC International, 16th edn. AOAC International, Gaithersburg, MD, USA, p 24, 127

  • Arregui LM, Quemada M (2006) Drainage and nitrate leaching in a crop rotation under different N-fertilizer strategies: application of capacitance probes. Plant Soil 288:57–69

    Article  CAS  Google Scholar 

  • Asare E, Scarisbrick DH (1995) Rate of nitrogen and sulphur fertilizers on yield, yield components and seed quality of oilseed rape (Brassica napus L.). Field Crop Res 44:41–46

    Article  Google Scholar 

  • AETC, Asociación Española de técnicos cerealistas (2009) Encuesta de calidad de los trigos españoles, cosecha 2008. Subdirección General de Investigación y Tecnología, INIA, Madrid

  • Barraclough PB (1989) Root growth, macro-nutrient uptake dynamics and soil fertility requirements of a high-yielding winter oilseed rape crop. Plant Soil 119:59–70

    Article  CAS  Google Scholar 

  • Bechmann M, Eggestad HO, Vagstad N (1998) Nitrogen balances and leaching in four agricultural catchments in southeastern Norway. Environ Pollut 102:493–499

    Article  CAS  Google Scholar 

  • Beckie HJ, Brandt SA, Schoenau JJ, Campbell CA, Henry JL, Janzen HH (1997) Nitrogen contribution of field pea in annual cropping systems. 2. Total nitrogen benefit. Can J Plant Sci 77:323–331

    Article  Google Scholar 

  • Black CA (1993) Soil fertility evaluation and control. Lewis Publishers, Boca Raton

    Google Scholar 

  • Blake GR, Hartge KH (1986) Bulk density. In: Klute A (ed) Methods of soil analysis. Part 1 Physical and mineralogical methods, 2nd edn. ASA–SSSA, Madison

  • Blake-Kalff MMA, Hawkesford MJ, Zhao FJ, McGrath SP (2000) Diagnosing sulfur deficiency in field-grown oilseed rape (Brassica napus L.) and wheat (Triticum aestivum L.). Plant Soil 225:95–107

    Article  CAS  Google Scholar 

  • Brennan RF, Mason MG, Walton GH (2000) Effect of nitrogen fertilizer on the concentrations of oil and protein in Canola (Brassica napus) seed. J Plant Nutr 23(3):339–348

    Article  CAS  Google Scholar 

  • Campbell GS (1985) Soil physics with BASIC: transport models for soil-plant systems. Elsevier, Amsterdam

    Google Scholar 

  • Campbell CA, Zentner RP, Basnyat P, De Jong R, Lemke R, Desjardins R (2008) Nitrogen mineralization under summer fallow and continuous wheat in the semiarid Canadian prairie. Can J Soil Sci 88:681–696

    Article  CAS  Google Scholar 

  • Casado H, Encinas D, Calzada I (1999) Depósito contaminante en la C.A.P.V. y sus posibles efectos sobre el Pinus radiata D. Don. Departamento de ordenación del territorio, vivienda y medio ambiente. Gobierno Vasco

  • CEC (1991) Council directive of 12th December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources (91/676/EEC). Off J Eur Commun (30/12/91 L135/1-8)

  • Cecotti SP (1996) Plant nutrient sulphur—a review of nutrient balance, environmental impact and fertilizers. Nutr Cycl Agroecosyst 43:117–125

    Google Scholar 

  • Christen O (2001) Effects of different preceding crops on the growth, yield components and grain yield of winter wheat and winter barley. In: Proceedings of 6th agronomy conference 1992. Australian Society of Agronomy

  • BOE n 45 viernes 21 de febrero de (2003) Ministerio de la Presidencia. Real Decreto 140/2003, de 7 de febrero, por el que se establecen los criterios sanitarios de la calidad del agua de consumo humano

  • Delogu G, Cattivelli L, Pecchioni N, De Falcis D, Maggiore T, Stanca AM (1998) Uptake and agronomic efficiency of nitrogen in winter barley and winter wheat. Eur J Agron 9:11–20

    Article  Google Scholar 

  • Eriksen J (1997) Sulphur cycling in Danish agricultural soils: inorganic sulphate dynamics and plant uptake. Soil Biol Biochem 29:1379–1385

    Article  CAS  Google Scholar 

  • Eriksen J, Askegaard M (2000) Sulphate leaching in an organic crop rotation on sandy soil in Denmark. Agric Ecosyst Environ 78:107–114

    Article  CAS  Google Scholar 

  • Eriksen J, Olesen JE, Askegaard M (2002) Sulphate leaching and sulphur balances of an organic cereal crop rotation on three Danish soils. Eur J Agron 17:1–9

    Article  CAS  Google Scholar 

  • Fismes J, Vong PC, Guckert A, Frossard E (2000) Influence of sulfur on apparent N-use efficiency, yield and quality of oilseed rape (Brassica napus L.) grown on a calcareous soil. Eur J Agron 12:127–141

    Article  CAS  Google Scholar 

  • Fitzgerald MA, David Ugalde T, Anderson JW (1999) Sulphur nutrition changes the sources of S in vegetative tissues of wheat during generative growth. J Exp Bot 50(333):499–508

    CAS  Google Scholar 

  • Flæte NES, Hollungb K, Ruudc L, Sogna T, Færgestadb EM, Skarpeidb HJ, Magnusb EM, Uhlena AK (2005) Combined nitrogen and sulphur fertilisation and its effect on wheat quality and protein composition measured by SE-FPLC and proteomics. J Cereal Sci 41:357–369

    Article  Google Scholar 

  • Flowers MD, Lutcher LK, Corp MK, Brown B (2007) Managing nitrogen for yield and protein in hard wheat. Oregon State University, Extension Service. FS 335

  • Gan YT, Campbell CA, Janzen HH, Lemke RL, Basnyat P, McDonald CL (2010) Nitrogen accumulation in plant tissues and roots and N mineralization under oilseeds, pulses, and spring wheat. Plant Soil 332:451–461

    Article  CAS  Google Scholar 

  • Gan YT, Liang BC, Liu LP, Wang XY, McDonald CL (2011) C:N ratios and carbon distribution profile across rooting zones in oilseed and pulse crops. Crop Pasture Sci 62:496–503

    Article  CAS  Google Scholar 

  • Gee GW, Bauder JW (1986) Particle-size analysis. In: Klute A (ed) Methods of soil analysis: part 1. Physical and mineralogical methods, 2nd edn. SSSA, Madison, pp 383–411

    Google Scholar 

  • GV-EJ, Gobierno Vasco-Eusko Jaurlaritza (1999) Decreto 390/1998 por el que se dictan normas para la declaración de Zonas Vulnerables a la contaminación de las aguas por los nitratos procedentes de la actividad agraria y se aprueba el Código de Buenas Prácticas Agrarias de la Comunidad Autónoma del País Vasco. BOPV 18:1448–1474

  • Goh KM, Pamidi J (2004) Effects of cultivation and long-term superphosphate applications on pasture soil sulphur mineralisation and availability in the field. Plant Soil 264:299–312

    Article  CAS  Google Scholar 

  • Goñi J, Irañeta J, Sexmilo JR, Lafarga A (2008) La colza en Navarra. Navarra Agraria 170:5–10

    Google Scholar 

  • Györi Z (2005) Sulphur content of winter wheat grain in long term field experiments. Commun Soil Sci Plant Anal 36:373–382

    Article  Google Scholar 

  • ITGA, Instituto Técnico para la Gestión Agrícola de Navarra (2005) Cultivos extensivos, campaña 2004. Informe Técnico Rep. 3. Instituto Técnico y de Gestión Agrícola, Villava, Spain

  • ITGA, Instituto Técnico para la Gestión Agrícola de Navarra (2009) Manual del cultivo de la colza de otoño en España

  • IUSS Grupo de Trabajo WRB (2007) Base Referencial Mundial del Recurso Suelo. Primera actualización 2007. Informes sobre Recursos Mundiales de Suelos No. 103. FAO, Roma

  • Jackson G (2000) Effect of nitrogen and sulphur on canola yield and nutrient uptake. Agron J 92(4):644–649

    Article  CAS  Google Scholar 

  • Janzen HH, Bettany JR (1984) Sulphur nutrition of rapeseed: I. influence of fertilizer nitrogen and sulfur rates. Soil Sci Soc Am J 48:100–107

    Article  CAS  Google Scholar 

  • Janzen HH, Ellert BH (1998) Sulphur dynamics in cultivated temperate agroecosystems. In: Maynard DG (ed) Sulphur in the environment. Marcel Dekker, New York, pp 11–43

    Google Scholar 

  • Järvan M, Edesi L, Adamson A, Lukme M, Akk A (2008) The effect of sulphur fertilization on yield, quality of protein and baking properties of winter wheat. Agron Res 6(2):459–469

    Google Scholar 

  • Johnson CM, Ulrich A (1959) Analytical methods for use in plant analysis. University of California Agricultural Experiment Station, Berkeley. Bulletin 766

  • Kirchmann H, Pichlmayer F, Gerzabeck MH (1996) Sulfur balances and sulphur-34 abundance in a long-term fertilizer experiment. Soil Sci Soc Am J 60:174–178

    Article  CAS  Google Scholar 

  • Kirkegaard JA, Gardner PA, Angus JF, Koetz E (1996) Effect of Brassica break crops on the growth and yield of wheat. Aust J Agric Res 45(3):529–545

    Article  Google Scholar 

  • Kirkegaard JA, Hocking PJ, Angus JF, Howe GN, Gardner PA (1997) Comparison of canola, Indian mustard and Linola in two contrasting environments. II. Break-crop and nitrogen effects on subsequent wheat crops. Field Crop Res 52:179–191

    Article  Google Scholar 

  • Kübler E, Hobelsberger A (1984) Beeinflussung von Ertrag Inhaltsstoffen und Nährstoffeinträgen bei Zuckerrüben, Winterweizen und Sommergerste durch gestaffelte N-Gaben während der neunjährigen Versuchsdauer des internationalen Stickstoffdüngungsversuches, Standort Ihinger Hof, II Winterweizen. Kali-Briefe 17:125–145

    Google Scholar 

  • Kumar K, Goh M (2000) Crop residues and management practices: effects on soil quality, soil nitrogen dynamics, crop yield, and nitrogen recovery. Adv Agron 68:197–318

    Article  CAS  Google Scholar 

  • Lancashire PD, Bleiholder H, Van Der Boom T, Langelüddeke P, Stauss R, Weber E, Witzenberger A (1991) A uniform decimal code for growth stages of crops and weeds. Ann Appl Biol 119:561–601

    Article  Google Scholar 

  • Lewandowski I, Kauter D (2003) The influence of nitrogen fertilizer on the yield and combustion quality of whole grain crops for solid fuel use. Ind Crop Prod 17:103–117

    Article  Google Scholar 

  • Lohaus G, Moellers C (2000) Phloem transport of amino acids in two Brassica napus L. genotypes and one B. carinata genotype in relation to their seed protein content. Planta 211:833–840

    Article  PubMed  CAS  Google Scholar 

  • Lord EI, Shepherd MA (1993) Developments in the use of ceramic cups for measuring nitrate leaching. J Soil Sci 24:435–449

    Google Scholar 

  • MAPA (1994) Métodos oficiales de análisis. Tomo III. Ministerio de Agricultura, Pesca y Alimentación. Madrid

  • Marschner H (1986) Uptake of mineral elements by leaves and other aerial plant parts. In: Marschner H (ed) Mineral nutrition in higher plants, pp 103–114

  • Maynard DG, Stewart JWB, Bettany JR (1983) Sulphur and nitrogen mineralization in soils compared using two incubation techniques. Soil Biol Biochem 15:251–256

    Article  CAS  Google Scholar 

  • McEwen J, Darby RJ, Hewitt MV, Yeoman DP (1989) Effects of field beans, fallow, lupins, oats, oilseed rape, peas, ryegrass, sunflowers and wheat on nitrogen residues in the soil and on the growth of a subsequent wheat crop. J Agric Sci 115:209–219

    Article  Google Scholar 

  • McGrath SP, Zhao FJ (1996) Sulphur uptake, yield response and the interactions between N and S in winter oilseed rape (Brassica napus). J Agric Sci 126:53–62

    Article  CAS  Google Scholar 

  • Millán S, Sampedro MC, Gallejones P, Castellón A, Ibargoitia ML, Goicolea MA, Barrio JR (2009) Identification and quantification of glucosinolates in rapeseed using liquid chromatography–ion trap mass spectrometry. Anal Bioanal Chem 394:1661–1669

    Article  PubMed  Google Scholar 

  • Monaghan JM, Scrimgeour CM, Stein WM, Zhao FJ, Evans EJ (1999) Sulphur accumulation and redistribution in wheat (Triticum aestivum): a study using stable sulphur isotope ratios as a tracer system. Plant Cell Environ 22:831–839

    Article  CAS  Google Scholar 

  • Ortuzar MA (2007) Desarrollo de un sistema de fertilización nitrogenada racional en trigo blando de invierno bajo condiciones de clima mediterráneo húmedo. Doctoral thesis, Universidad del País Vasco, Leioa

  • Ortuzar MA, Castellón A, Alonso A, Besga G, Estavillo JM, Aizpurua A (2010) Estimation of optimum nitrogen fertilizer rates in winter wheat in humid mediterranean conditions. I. Selection of yield and protein response models. Commun Soil Sci Plant Anal 41(19):2293–2300

    Article  Google Scholar 

  • Ortuzar-Iragorri MA, Aizpurua A, Castellón A, Alonso A, Unamunzaga O, Azkorra Z, Estavillo JM (2006) Balances de nitrógeno en cultivo de trigo de invierno en el País Vasco. Monografías INIA: Serie agrícola no. 21:29–47

  • Papadakis J (1966) Climates of the world and their agricultural potentialities. Edited by the author. Buenos Aires

  • Quemada M (2006) Balance de nitrógeno en sistemas de cultivo de cereal de invierno y de maíz en varias regiones españolas. Monografías INIA, serie agrícola no. 21

  • Randall PJ, Wrigley CW (1986) Effects of sulfur supply on yield, composition, and quality of grain from cereals, oilseeds, and legumes. Adv Cereal Sci Technol 8:171–206

    CAS  Google Scholar 

  • Randall PJ, Spencer K, Freney JR (1981) Sulfur and nitrogen fertilizer effects on wheat. I Concentrations of sulfur and nitrogen and the nitrogen to sulfur ratio in grain, in relation to the yield response. Aust J Agric Res 32:203–212

    Article  CAS  Google Scholar 

  • Rathke GW, Christen O, Diepenbrock W (2005) Effects of nitrogen source and rate on productivity and quality of winter oilseed rape (Brassica napus L.) grown in different crop rotations. Field Crop Res 94(2–3):103–113

    Article  Google Scholar 

  • Rathke GW, Behrens T, 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. Agric Ecosyst Environ 117:80–108

    Article  CAS  Google Scholar 

  • Rieger S, Richner W, Streit B, Frossard E, Liedgens M (2008) Growth, yield, and yield components of winter wheat and the effects of tillage intensity, preceding crops, and fertilisation. Eur J Agron 28:405–411

    Article  CAS  Google Scholar 

  • Rossato L, Lainé P, Ourry A (2001) Nitrogen storage and remobilization in Brassica napus L. during the growth cycle: nitrogen fluxes within the plant and changes in soluble protein patterns. J Exp Bot 52:1655–1663

    Article  PubMed  CAS  Google Scholar 

  • Sahota TS (2006) Importance of sulphur in crop production. Northwest Link, 10–12 Sept

  • Salvagiotti F, Castellarín JM, Miralles DJ, Pedrol HM (2009) Sulfur fertilization improves nitrogen use efficiency in wheat by increasing nitrogen uptake. Field Crop Res 113(2):170–177

    Article  Google Scholar 

  • SAS Institute (2004) SAS version 9.1. SAS Institute, Cary

  • Shepherd MA, Sylvester-Bradley P (1996) Effect of nitrogen fertilizer applied to winter oilseed rape (Brassica napus) on soil mineral nitrogen after harvest and on the response of a succeeding crop of winter wheat to nitrogen fertilizer. J Agric Sci 126:63–74

    Article  CAS  Google Scholar 

  • Sieling K, Kage H (2006) N balance as an indicator of N leaching in an oilseed rape–winter wheat–winter barley rotation. Agric Ecosyst Environ 115:261–269

    Article  CAS  Google Scholar 

  • Sieling K, Kage H (2010) Efficient N management using winter oilseed rape. A review. Agron Sustain Dev 30:271–279

    Article  CAS  Google Scholar 

  • Sieling K, Günther-Borstel O, Teebken T, Hanus H (1999) Soil mineral N and N net mineralization during autumn and winter under an oilseed rape–winter wheat–winter barley rotation in different crop management systems. J Agric Sci 132:127–137

    Article  Google Scholar 

  • Sieling K, Brase T, Svib V (2006) Residual effects of different N fertilizer treatments on growth, N uptake and yield of oilseed rape, wheat and barley. Eur J Agron 25:40–48

    Article  CAS  Google Scholar 

  • SSS, Soil Survey Staff (2010) Keys to soil taxonomy, 11th edn. USDA-Natural Resources Conservation Service, Washington, DC

    Google Scholar 

  • Stout BA (1990) Handbook of energy for world agriculture. Elsevier, London

    Book  Google Scholar 

  • Talebnia F, Karakashev D, Angelidaki I (2010) Production of bioethanol from wheat straw: an overview on pretreatment, hydrolysis and fermentation. Bioresour Technol 101:4744–4753

    Article  PubMed  CAS  Google Scholar 

  • Walkley A, Black IA (1934) An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Sci 37:29–38

    Article  CAS  Google Scholar 

  • Watanabe FS, Olsen SR (1965) Test of an ascorbic acid method for determining phosphorus in water and NaHCO3 extracts from soil. Soil Sci Soc Am Proc 29:677–678

    Article  CAS  Google Scholar 

  • Withers PJA, O’Donnell FM (1994) The response of double-low winter oilseed rape to fertiliser sulphur. J Sci Food Agric 63:29–37

    Google Scholar 

  • Zadoks JC, Chang TT, Konzak CF (1974) A decimal code for the growth stages of cereals. Weed Res 14:415–421

    Article  Google Scholar 

  • Zasoski RJ, Burau RG (1977) A rapid nitric-perchloric acid digestion method for multielement tissue analysis. Commun Soil Sci Plant Anal 8(5):425–436

    Article  CAS  Google Scholar 

  • Zhao FJ, McGrath SP (1994) Comparison of sulphur uptake by oilseed rape and the soil sulphur status of two adjacent fields with different soil series. Soil Use Manag 10:47–50

    Article  Google Scholar 

  • Zhao FJ, Withers PJA, Evans EJ, Monaghan J, Salmon SE, Shewry PR, McGrath SP (1997) Sulphur nutrition: an important factor for the quality of wheat and rapeseed. Soil Sci Plant Nutr 43:1137–1142

    Article  CAS  Google Scholar 

  • Zhao FJ, Salmon SE, Withers PJA, Monaghan JM, Evans EJ, Shewry PR, McGrath SP (1999a) Variation in the breadmaking quality and rheological properties of wheat in relation to sulphur nutrition under field conditions. J Cereal Sci 30:19–31

    Article  Google Scholar 

  • Zhao FJ, Hawkesford MJ, McGrath SP (1999b) Sulphur assimilation and effects on yield and quality of wheat. J Cereal Sci 30:1–17

    Article  CAS  Google Scholar 

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Acknowledgments

This work was supported by the Ministry of Science and Innovation (MICINN-INIA RTA2005-00219-C03-02) and the Department of the Environment, Regional planning, Agriculture and Fisheries of the Basque Government. The authors are grateful to the Department of Analytical Chemistry (Faculty of Pharmacy of the UPV) for the analysis of glucosinolates in the seed of rapeseed. We thank Tom Misselbrook for reviewing the English.

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Gallejones, P., Castellón, A., del Prado, A. et al. Nitrogen and sulphur fertilization effect on leaching losses, nutrient balance and plant quality in a wheat–rapeseed rotation under a humid Mediterranean climate. Nutr Cycl Agroecosyst 93, 337–355 (2012). https://doi.org/10.1007/s10705-012-9520-2

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