22 results
Registry-based trials: a potential model for cost savings?
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- Brett R. Anderson, Evelyn G. Gotlieb, Kevin Hill, Kimberly E. McHugh, Mark A. Scheurer, Carlos M. Mery, Glenn J. Pelletier, Jonathan R. Kaltman, Owen J. White, Felicia L. Trachtenberg, Danielle Hollenbeck-Pringle, Brian W. McCrindle, Donna M. Sylvester, Aaron W. Eckhauser, Sara K. Pasquali, Jeffery B. Anderson, Marcus S. Schamberger, Subhadra Shashidharan, Jeffrey P. Jacobs, Marshall L. Jacobs, Marko Boskovski, Jane W. Newburger, Meena Nathan
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- Cardiology in the Young / Volume 30 / Issue 6 / June 2020
- Published online by Cambridge University Press:
- 08 May 2020, pp. 807-817
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Background/Aims:
Registry-based trials have emerged as a potentially cost-saving study methodology. Early estimates of cost savings, however, conflated the benefits associated with registry utilisation and those associated with other aspects of pragmatic trial designs, which might not all be as broadly applicable. In this study, we sought to build a practical tool that investigators could use across disciplines to estimate the ranges of potential cost differences associated with implementing registry-based trials versus standard clinical trials.
Methods:We built simulation Markov models to compare unique costs associated with data acquisition, cleaning, and linkage under a registry-based trial design versus a standard clinical trial. We conducted one-way, two-way, and probabilistic sensitivity analyses, varying study characteristics over broad ranges, to determine thresholds at which investigators might optimally select each trial design.
Results:Registry-based trials were more cost effective than standard clinical trials 98.6% of the time. Data-related cost savings ranged from $4300 to $600,000 with variation in study characteristics. Cost differences were most reactive to the number of patients in a study, the number of data elements per patient available in a registry, and the speed with which research coordinators could manually abstract data. Registry incorporation resulted in cost savings when as few as 3768 independent data elements were available and when manual data abstraction took as little as 3.4 seconds per data field.
Conclusions:Registries offer important resources for investigators. When available, their broad incorporation may help the scientific community reduce the costs of clinical investigation. We offer here a practical tool for investigators to assess potential costs savings.
Extraneural Metastases of a Cerebral Astrocytoma
- Harold J. Hoffman, Larry E. Becker, Derek Jenkin, Sylvester H. Chuang, Ian R. Munro
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- Journal:
- Canadian Journal of Neurological Sciences / Volume 8 / Issue 2 / May 1981
- Published online by Cambridge University Press:
- 18 September 2015, pp. 115-119
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Extraneural spread of a cerebral glioma has been described infrequently. The present case provides an example of this unique mode of metastasis.
Contributors
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. Jacob, Arthur James, Maria Jansdotter-Samuelsson, David Jasper, Werner G. Jeanrond, Renée Jeffery, David Lyle Jeffrey, Theodore W. Jennings, David H. Jensen, Robin Margaret Jensen, David Jobling, Dale A. Johnson, Elizabeth A. Johnson, Maxwell E. Johnson, Sarah Johnson, Mark D. Johnston, F. Stanley Jones, James William Jones, John R. Jones, Alissa Jones Nelson, Inge Jonsson, Jan Joosten, Elizabeth Judd, Mulambya Peggy Kabonde, Robert Kaggwa, Sylvester Kahakwa, Isaac Kalimi, Ogbu U. Kalu, Eunice Kamaara, Wayne C. Kannaday, Musimbi Kanyoro, Veli-Matti Kärkkäinen, Frank Kaufmann, Léon Nguapitshi Kayongo, Richard Kearney, Alice A. Keefe, Ralph Keen, Catherine Keller, Anthony J. Kelly, Karen Kennelly, Kathi Lynn Kern, Fergus Kerr, Edward Kessler, George Kilcourse, Heup Young Kim, Kim Sung-Hae, Kim Yong-Bock, Kim Yung Suk, Richard King, Thomas M. King, Robert M. Kingdon, Ross Kinsler, Hans G. Kippenberg, Cheryl A. Kirk-Duggan, Clifton Kirkpatrick, Leonid Kishkovsky, Nadieszda Kizenko, Jeffrey Klaiber, Hans-Josef Klauck, Sidney Knight, Samuel Kobia, Robert Kolb, Karla Ann Koll, Heikki Kotila, Donald Kraybill, Philip D. W. Krey, Yves Krumenacker, Jeffrey Kah-Jin Kuan, Simanga R. Kumalo, Peter Kuzmic, Simon Shui-Man Kwan, Kwok Pui-lan, André LaCocque, Stephen E. Lahey, John Tsz Pang Lai, Emiel Lamberts, Armando Lampe, Craig Lampe, Beverly J. Lanzetta, Eve LaPlante, Lizette Larson-Miller, Ariel Bybee Laughton, Leonard Lawlor, Bentley Layton, Robin A. Leaver, Karen Lebacqz, Archie Chi Chung Lee, Marilyn J. Legge, Hervé LeGrand, D. L. LeMahieu, Raymond Lemieux, Bill J. Leonard, Ellen M. Leonard, Outi Leppä, Jean Lesaulnier, Nantawan Boonprasat Lewis, Henrietta Leyser, Alexei Lidov, Bernard Lightman, Paul Chang-Ha Lim, Carter Lindberg, Mark R. Lindsay, James R. Linville, James C. Livingston, Ann Loades, David Loades, Jean-Claude Loba-Mkole, Lo Lung Kwong, Wati Longchar, Eleazar López, David W. Lotz, Andrew Louth, Robin W. Lovin, William Luis, Frank D. Macchia, Diarmaid N. J. MacCulloch, Kirk R. MacGregor, Marjory A. MacLean, Donald MacLeod, Tomas S. Maddela, Inge Mager, Laurenti Magesa, David G. Maillu, Fortunato Mallimaci, Philip Mamalakis, Kä Mana, Ukachukwu Chris Manus, Herbert Robinson Marbury, Reuel Norman Marigza, Jacqueline Mariña, Antti Marjanen, Luiz C. L. Marques, Madipoane Masenya (ngwan'a Mphahlele), Caleb J. D. Maskell, Steve Mason, Thomas Massaro, Fernando Matamoros Ponce, András Máté-Tóth, Odair Pedroso Mateus, Dinis Matsolo, Fumitaka Matsuoka, John D'Arcy May, Yelena Mazour-Matusevich, Theodore Mbazumutima, John S. McClure, Christian McConnell, Lee Martin McDonald, Gary B. McGee, Thomas McGowan, Alister E. McGrath, Richard J. McGregor, John A. McGuckin, Maud Burnett McInerney, Elsie Anne McKee, Mary B. McKinley, James F. McMillan, Ernan McMullin, Kathleen E. McVey, M. 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Phan, Isabel Apawo Phiri, William S. F. Pickering, Derrick G. Pitard, William Elvis Plata, Zlatko Plese, John Plummer, James Newton Poling, Ronald Popivchak, Andrew Porter, Ute Possekel, James M. Powell, Enos Das Pradhan, Devadasan Premnath, Jaime Adrían Prieto Valladares, Anne Primavesi, Randall Prior, María Alicia Puente Lutteroth, Eduardo Guzmão Quadros, Albert Rabil, Laurent William Ramambason, Apolonio M. Ranche, Vololona Randriamanantena Andriamitandrina, Lawrence R. Rast, Paul L. Redditt, Adele Reinhartz, Rolf Rendtorff, Pål Repstad, James N. Rhodes, John K. Riches, Joerg Rieger, Sharon H. Ringe, Sandra Rios, Tyler Roberts, David M. Robinson, James M. Robinson, Joanne Maguire Robinson, Richard A. H. Robinson, Roy R. Robson, Jack B. Rogers, Maria Roginska, Sidney Rooy, Rev. Garnett Roper, Maria José Fontelas Rosado-Nunes, Andrew C. Ross, Stefan Rossbach, François Rossier, John D. Roth, John K. Roth, Phillip Rothwell, Richard E. 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Yee, Viktor Yelensky, Yeo Khiok-Khng, Gustav K. K. Yeung, Angela Yiu, Amos Yong, Yong Ting Jin, You Bin, Youhanna Nessim Youssef, Eliana Yunes, Robert Michael Zaller, Valarie H. Ziegler, Barbara Brown Zikmund, Joyce Ann Zimmerman, Aurora Zlotnik, Zhuo Xinping
- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
- Published online:
- 05 August 2012
- Print publication:
- 20 September 2010, pp xi-xliv
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An evaluation of phase separated, self-assembled LaMnO3-MgO nanocomposite films directly on IBAD-MgO as buffer layers for flux pinning enhancements in YBa2Cu3O7-δ coated conductors
- Özgür Polat, Tolga Aytug, M. Parans Paranthaman, Keith J. Leonard, Andrew R. Lupini, Steve J. Pennycook, Harry M. Meyer, Kim Kim, Xiaofeng Qiu, Sylvester Cook, James R. Thompson, David K. Christen, Amit Goyal, Xumin Xiong, Venkat Selvamanickam
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- Journal:
- Journal of Materials Research / Volume 25 / Issue 3 / March 2010
- Published online by Cambridge University Press:
- 31 January 2011, pp. 437-443
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- March 2010
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Technological applications of high temperature superconductors (HTS) require high critical current density, Jc, under operation at high magnetic field strengths. This requires effective flux pinning by introducing artificial defects through creative processing. In this work, we evaluated the feasibility of mixed-phase LaMnO3:MgO (LMO:MgO) films as a potential cap buffer layer for the epitaxial growth and enhanced performance of YBa2Cu3O7-δ (YBCO) films. Such composite films were sputter deposited directly on IBAD-MgO templates (with no additional homo-epitaxial MgO layer) and revealed the formation of two phase-separated, but at the same time vertically aligned, self-assembled composite nanostructures that extend throughout the entire thickness of the film. The YBCO coatings deposited on these nanostructured cap layers showed correlated c-axis pinning and improved in-field Jc performance compared to those of YBCO films fabricated on standard LMO buffers. Microstructural characterization revealed additional extended disorder in the YBCO matrix. The present results demonstrate the feasibility of novel and potentially practical approaches in the pursuit of more efficient, economical, and high performance superconducting devices.
A comparison of the responses of two cultivars of late-autumn-sown wheat to applied nitrogen
- J. Webb, R. Sylvester-Bradley
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- Journal:
- The Journal of Agricultural Science / Volume 125 / Issue 1 / August 1995
- Published online by Cambridge University Press:
- 27 March 2009, pp. 11-24
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At four pairs of sites in the UK, two cultivars of wheat, bred either for autumn (cv. Mercia) or for spring (cv. Tonic) sowing were sown in November 1988 and 1989 and their yield response to springapplied fertilizer N assessed over the range 0–320 kg/ha N. Grain samples were taken at harvest and analysed for those qualities regarded as indicators of suitability for milling. In five experiments, the grain yield of Mercia was up to 1 t/ha greater than that of Tonic, but overall there was no consistent difference between the two cultivars in the optimum economic yield (Yopt)or in the amount of fertilizer N needed to produce it (Nopt). Both cultivars produced c. 17·5 kg of grain per kg of fertilizer N applied up to Nopl. In the five experiments in which Tonic yielded less, it produced grain of greater N concentration than Mercia when given the same amount of fertilizer N. Differences in grain N concentration, while small (< 0·3%), were significant when analysed across sites. In six experiments both cultivars produced grain of 11 % protein at Nopt. There were no consistent or worthwhile increases in specific weight, Hagberg falling number (HFN) or response to the sodium dodecyl sulphate (SDS) sedimentation test of either cultivar from applying more fertilizer N than Nopl. The average specific weight of Mercia grain was 2·5 kg/hi greater than that of Tonic, while Tonic gave larger SDS values of c. 8. There was little difference in HFN. It was concluded that the yield requirement for fertilizer N was similar for these two cultivars of wheat when sown in late autumn, and there was no need to apply differential fertilizer N applications to the cultivars to produce grain of the quality needed for breadmaking. In four experiments the application of plant growth regulator (PGR) increased the yields of both cultivars by c. 0·5 t/ha.
Influence of sowing date on the uptake of and responses to soil and fertilizer nitrogen by the spring wheat cultivar Tonic
- J. Webb, R. Sylvester-Bradley, J. D. Wafford
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- The Journal of Agricultural Science / Volume 125 / Issue 1 / August 1995
- Published online by Cambridge University Press:
- 27 March 2009, pp. 25-37
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At 14 sites in the UK, spring wheat (Triticum aestivum) cv. Tonic, was sown on three or four dates at each site between October and March in the 1988/89, 1989/90 and 1990/91 seasons. Responses to spring-applied fertilizer N over the range 0–320 kg/ha were determined. Earlier sowing did not increase uptake of soil N by the crop. Fertilizer N increased grain N offtake by between 25 and 140 kg/ha and yield by between 0·3 and 5·5 t/ha, although grain yield was less responsive to fertilizer N at later sowing dates. Apparent recovery of fertilizer N (AFR) also decreased as sowing was delayed but there was no effect of delayed sowing on the amount of grain produced from each kg of fertilizer N recovered. Because fertilizer N recovery decreased with later sowing, the amount of fertilizer N needed to produce the optimum economic grain yield was not reduced. Neither AFR nor optimum fertilizer (Nopt) was related to optimum yield. Regression of Nopt on the difference between optimum yield and yield without fertilizer N (△y) explained 77% of the variance in Nopt. There was an inverse relationship between △y and soil mineral N (SMN) in spring; regression of △y, on SMN in spring accounted for 29% of the variance in △y Current advisory systems which adjust economic fertilizer N recommendations according to anticipated yield are not justified by these results. Moreover the adjustments made, based on yield expectation, appear about three times as large as those needed to minimize residues of fertilizer N left unrecovered by the crop and to reduce the risk of nitrate leaching in the following winter.
Effects of fertilizer nitrogen on soil nitrogen availability after a grazed grass ley and on the response of the following cereal crops to fertilizer nitrogen
- J. Webb, R. Sylvester-Bradley
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- Journal:
- The Journal of Agricultural Science / Volume 122 / Issue 3 / June 1994
- Published online by Cambridge University Press:
- 27 March 2009, pp. 445-457
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Nitrogen nutrition of two succeeding wheat crops was studied after ploughing of grassland in July 1987 on a clay soil at ADAS Drayton. The four plots of grassland had received 100, 250, 450 and 750 kg N/ha per year for 4 years from 1984 and were grazed by beef cattle at stocking densities which varied according to grass growth.
Determinations of soil mineral N taken to 60 cm every 3 weeks from July to the following May were particularly variable. However, in the first 2 years after ploughing the means of the series of mineral N measurements were directly proportional to the amounts of fertilizer N applied to the grass.
N offtake in winter wheat grain without fertilizer N was directly proportional to fertilizer N applied to grass but this had little effect on maximum grain yields. Large soil N supplies did not necessarily predispose the wheat crops to large grain N concentrations because fertilizer N caused grain N offtake to reach a similar maximum, irrespective of previous grass N.
Optimum amounts of fertilizer N for the wheat were 188, 147, 87 and nil kg/ha in 1988 and 152,130, 89 and 25 kg/ha in 1989 after 100, 250, 450 and 750 kg N/ha per year applied to the grass. Soil N supply as indicated by both the amount of fertilizer applied to grass and means of mineral N measurements accounted for almost all of this variation. Mean soil mineral N over winter was no better as an indicator of soil N supply than the amount of N applied to the grass. However, before adopting N applied to grass as a more general index of N supply, it would need to be adjusted for variation in N removed and lost during grass growth; these were controlled in this experiment.
Effects of cultivation and nitrification inhibitor on soil nitrogen availability after a grass ley and on the response of the following cereal crop to fertilizer nitrogen
- J. Webb, M. Froment, R. Sylvester-Bradley
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- Journal:
- The Journal of Agricultural Science / Volume 117 / Issue 1 / August 1991
- Published online by Cambridge University Press:
- 27 March 2009, pp. 9-21
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Three experiments carried out at Bridget's Experimental Husbandry Farm, Hampshire between 1984 and 1987 on clay loam and silty clay loam soils over chalk investigated the response of winter wheat grown after grass to spring-applied fertilizer nitrogen. The influence of method of establishment and the use of a nitrification inhibitor were also studied. Yields were similar whether the crops were established by direct drilling or following ploughing. Crops required between 88 and 209 kg N/ha nitrogen fertilizer for optimum yield. There was no consistent difference in nitrogen requirement nor were there consistent differences in nitrogen offtake (which is the amount of N in kg/ha removed in harvested grain) or apparent fertilizer recovery following ploughing or direct drilling. The use of a nitrification inhibitor increased grain yield when applied in the autumn without fertilizer, but not when applied with fertilizer in the spring.
PAPER PRESENTED AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 Genetic progress in yield potential in wheat: recent advances and future prospects
- M. J. FOULKES, J. W. SNAPE, V. J. SHEARMAN, M. P. REYNOLDS, O. GAJU, R. SYLVESTER-BRADLEY
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- Journal:
- The Journal of Agricultural Science / Volume 145 / Issue 1 / February 2007
- Published online by Cambridge University Press:
- 25 January 2007, pp. 17-29
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Knowledge of the changes in physiological traits associated with genetic gains in yield potential is essential to improve understanding of yield-limiting factors and to inform future breeding strategies. Recent advances in genetic yield potential and associated physiological changes in wheat (Triticum aestivum L.) are reviewed. Genetic gains in yield potential worldwide have been both positively correlated with harvest index (HI) and above-ground dry matter (AGDM), with more frequent reports of yield progress associated with biomass since about 1990. It is concluded that an important aim of future breeding will be the increase of biomass production while maintaining the present values of HI. In winter wheat recent biomass progress has been positively associated with pre-anthesis radiation-use efficiency (RUE) and water-soluble carbohydrate (WSC) content of stems at anthesis. Present results in two doubled-haploid (DH) populations show a positive linear relationship between stem WSC and grain yield in the UK environment. Results from various investigations worldwide in recent years have demonstrated that biomass increases have been associated with particular introductions of alien genes into wheat germplasm, e.g. the 1BL.1RS wheat-rye translocation and the 7DL.7Ag wheat-Agropyron elongatum translocation. Present results confirm a positive effect of 1BL.1RS on harvest biomass in two DH populations in the UK. The future prospects for identifying physiological traits to raise yield potential are considered with particular reference to winter wheat grown in northwestern Europe. It is proposed that optimized rooting traits, an extended stem-elongation phase, greater RUE, greater stem WSC storage and optimized ear morphology will be important for breeding progress in yield potential in future years.
The ability of wheat cultivars to withstand drought in UK conditions: formation of grain yield
- M. J. FOULKES, R. K. SCOTT, R. SYLVESTER-BRADLEY
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- Journal:
- The Journal of Agricultural Science / Volume 138 / Issue 2 / March 2002
- Published online by Cambridge University Press:
- 12 April 2002, pp. 153-169
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Experiments in three dry years, 1993/94, 1994/95 and 1995/96, on a medium sand at ADAS Gleadthorpe, England, tested responses of six winter wheat cultivars to irrigation of dry-matter growth, partitioning of dry matter to leaf, stem and ear throughout the season, and to grain at final harvest. Cultivars (Haven, Maris Huntsman, Mercia, Rialto, Riband and Soissons) were selected for contrasts in flowering date and stem soluble carbohydrate. Maximum soil moisture deficit (SMD) exceeded 140 mm in all years, with large deficits (>75 mm) from early June in 1994 and from May in 1995 and 1996. The main effects of drought on partitioning of biomass were for a decrease in the proportion of the crop as lamina in the pre-flowering period, and then earlier retranslocation of stem reserves to grains during the first half of grain filling. Restricted water availability decreased grain yield by 1·83 t/ha in 1994 (P<0·05), and with more prolonged droughts, by 3·06 t/ha in 1995 (P<0·001) and by 4·55 t/ha in 1996 (P<0·001). Averaged over the three years, grain yield responses of the six cultivars differed significantly (P<0·05). Rialto and Mercia lost only 2·8 t/ha compared with Riband and Haven which lost 3·5 t/ha. Losses for Soissons and Maris Huntsman were intermediate. In the two years with prolonged drought, the biomass depression was on average greater for Haven (6·0 t/ha) than for Maris Huntsman (4·2 t/ha) (P<0·05). Thus, the grain yield sensitivity of Haven to drought derived, in part, from a sensitivity of biomass growth to drought. Harvest index (HI; ratio of grain to above-ground dry matter at harvest) responses of the six cultivars to irrigation also differed (P<0·05) and contributed to the yield responses. The smallest decrease in HI of the six cultivars with restricted water availability was shown by Rialto (−0·033); this partially explained the drought resistance for this cultivar. The largest decrease was for Maris Huntsman (−0·072). The cultivars differed in flowering dates by up to 9 days but these were poorly correlated with grain yield responses to irrigation. Stem soluble carbohydrate at flowering varied amongst cultivars from 220 to 300 g/m2 in the unirrigated crop; greater accumulation appeared to be associated with better maintenance of HI under drought. It is concluded that high stem-soluble carbohydrate reserves could be used to improve drought resistance in the UK's temperate climate, but that early flowering seems less likely to be useful.
The ability of wheat cultivars to withstand drought in UK conditions: resource capture
- M. J. FOULKES, the late R. K. SCOTT, R. SYLVESTER-BRADLEY
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- Journal:
- The Journal of Agricultural Science / Volume 137 / Issue 1 / August 2001
- Published online by Cambridge University Press:
- 24 October 2001, pp. 1-16
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Experiments in three dry seasons (1993/94, 1994/95, 1995/96) on a loamy medium sand at ADAS Gleadthorpe, Nottinghamshire, England tested responses of green area, radiation interception, water uptake and above-ground dry matter growth of six wheat cultivars to irrigation. Cultivars differing in date of introduction (Haven 1987, Maris Huntsman 1969, Mercia 1983, Rialto 1991, Riband 1985 and Soissons 1989) were chosen for contrast in flowering time and maximum green area. Maximum soil moisture deficit (SMD) exceeded 140 mm in all years, with large deficits (> 75 mm) from early June in 1994 and more prolonged large deficits in 1995 and 1996. Restricted water availability first affected canopy expansion at a SMD of 74 mm (50% available water capacity; AW), and canopy senescence at 95 mm (64% AW). Decreases in biomass at harvest were larger with prolonged droughts in 1995 and 1996 (424–562 g/m2) than in 1994 (222 g/m2). Compared in the two driest years, 1995 and 1996, the decrease in biomass was greater in Haven (599 g/m2) than in Maris Huntsman (420 g/m2) (P < 0·05). The better drought resistance of Maris Huntsman appeared to arise through its greater water use efficiency (WUE); 6·2 cf. 5·5–5·7 g/m2/mm. The susceptibility of Haven to drought was possibly due to restricted water uptake, depression of radiation use efficiency (RUE) and accelerated senescence. The cultivars differed in flowering by up to 9 days but date of flowering correlated poorly with biomass response to irrigation. Early flowering was, however, correlated with favourable distribution of seasonal water use with respect to the grain filling period. The maximum green area index (GAI) of cultivars varied from 4·4 to 5·3 (P < 0·01), but differences were countered by shifts in the extinction coefficient (K), such that season-long radiation interception varied little. Green area index maxima did not therefore relate to the pattern of growth or water use, and they were correlated poorly with the biomass responses. Cultivars did not differ in their maximum depth of water extraction; they all extracted water to 1·65 m depth in each year. It is concluded that early flowering and high WUE might offer scope for improving drought resistance in the UK's temperate climate, but that small maximum GAI seems less useful.
An approach to modelling the effect of environmental and physiological factors upon biomass accumulation in winter wheat
- A. G. GILLETT, N. M. J. CROUT, D. T. STOKES, R. SYLVESTER-BRADLEY, R. K. SCOTT
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- Journal:
- The Journal of Agricultural Science / Volume 136 / Issue 4 / June 2001
- Published online by Cambridge University Press:
- 16 July 2001, pp. 369-381
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Six sites of variable soil type and environments in England and Scotland were sown with winter wheat (Triticum aestivum L. cv. Mercia) in the autumns of 1992 and 1993 with optimum inputs for growth. Crop monitoring between February and grain maturity provided data to investigate environmental and physiological factors important in controlling biomass accumulation.
With increasing use of crop modelling as a tool for interpreting experiments and as crop management decision support systems, it is important that all influences on crop productivity are understood. The ‘radiation use efficiency’ or radiation conversion coefficient provides a convenient basis to study these influences.
Significant differences in seasonal radiation conversion coefficients were observed between sites (P < 0·001), ranging from 2·82 to 3·87 g total dry matter/MJ absorbed photosynthetically active radiation. A series of simple dry matter models were developed to help explain biomass accumulation in relation to a number of environmental variables (using the measured green area index as an input) with correlation coefficients [ges ] 0·98 obtained across all sites. Apart from sunlight, differences in the canopy's ability to accumulate nitrogen and maintenance respiration costs were the most significant factors (P < 0·001). The nitrogen effect suggests changes in the conversion of assimilates with nitrogen availability, despite relatively high nutrition levels ([ges ] 180 kg N/ha).
Over all sites the canopy extinction coefficient could be described as a linear function of the site spring time plant population (P < 0·01). A more detailed model considered canopy light attenuation to vary between sites according to sowing date and autumn/winter plant establishment and environment.
Availability of nitrogen after fertilizer applications to cereals
- J. A. KING, R. SYLVESTER-BRADLEY, A. D. H. ROCHFORD
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- Journal:
- The Journal of Agricultural Science / Volume 136 / Issue 2 / March 2001
- Published online by Cambridge University Press:
- 25 April 2001, pp. 141-157
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An experiment was conducted over seven sites in eastern England sown to winter cereals, whereby the soil mineral nitrogen (N) and N recovery in the crop were measured frequently during the active growth period. Plots received 100 kg/ha fertilizer N on one of three dates in spring (28 March, 11 April and 25 April) on each site in each of the three years (1994 to 1996), and these were compared with controls with no applied N. At one site, uncropped plots were included, and measurements of gaseous N emission, soil respiration, soil microbial biomass and root tissue N concentration were also made. The fertilizer applications boosted yields by at least 3 t/ha at all sites, but apparent recovery of fertilizer N varied throughout the previously known range of 45–85%. Soil type and timing of application had no effect on N recovery, or on final yields. N was mineralized from soil sources throughout the growth period, but mineralization was outweighed by ‘‘immobilization’’ of large amounts of N (around 30 kg/ha) in the soil, chiefly during May when crop growth was most rapid. This occurred on all sites with a crop, but not where the crop was absent. Measured losses of N2 and N2O were very small (<70 g/ha/dayN) on the site where they were measured, and no other evidence of loss or storage of N was found. The apparent recovery of fertilizer N at each site, was almost exactly explained by the amount immobilized during May. We conclude that the poor recovery of spring-applied N was due, not to losses as previously assumed but to temporary immobilization during the period of most active crop uptake. Immobilization was caused primarily by the presence of the crop.
Simple winter wheat green area index model under UK conditions
- A. G. GILLETT, N. M. J. CROUT, D. T. STOKES, R. SYLVESTER-BRADLEY, R. K. SCOTT
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- Journal:
- The Journal of Agricultural Science / Volume 132 / Issue 3 / May 1999
- Published online by Cambridge University Press:
- 01 May 1999, pp. 263-271
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A simple model of canopy expansion and senescence with accumulated thermal time from sowing was used to describe differences in canopy development and potential size across a range of sites in the UK between 1992 and 1995. The principal model inputs were nitrogen, temperature and sowing date. The model was calibrated across six sites within the major wheat growing areas using canopy data collected during the 1992/93 and 1993/94 growing seasons and was validated using data collected in the 1994/95 season. The model was able to predict the time course of green area index (GAI) over a season with an r2[ges ]0·87 for the five English sites, and an r2=0·68 for the single Scottish site. This model may prove to be a useful approach to forecasting the potential canopy size, based upon an estimate or measure of the total nitrogen available to the crop (both from applied fertilizer and the soil).
Silicate and ice emission bands in the ISO spectrum of the PAH-emitting carbon-rich planetary nebula CPD-56°8032
- Martin Cohen, M. J. Barlow, R. J. Sylvester, X.-W. Liu, P. Cox, T. Lim, B. Schmitt, A. K. Speck
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- Symposium - International Astronomical Union / Volume 191 / 1999
- Published online by Cambridge University Press:
- 25 May 2016, pp. 291-296
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- 1999
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Combined ISO SWS and LWS spectroscopy is presented of the late WC-type planetary nebula nucleus CPD-56†8032 and its carbon-rich nebula. The extremely broad coverage (2.4–197 μm) enables us to recognize the clear and simultaneous presence of emission features from both oxygen- and carbon-rich circumstellar materials. Removing a smooth continuum highlights bright emission bands characteristic of polycyclic aromatic hydrocarbons (hereafter PAHs) in the 3–15 μm region, bands from crystalline silicates longwards of 18 μm, and the 43- and 62-μm bands of crystalline water ice. We discuss the probable evolutionary state and history of this unusual object in terms of (a) a recent transition from an O-rich to a C-rich outflow following a helium shell flash; or (b) a carbon-rich nebular outflow encountering an O-rich comet cloud orbiting in a Kuiper-belt-like distribution.
Effects of nitrogen fertilizer on the grain yield and quality of winter oats
- A. G. CHALMERS, C. J. DYER, R. SYLVESTER-BRADLEY
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- Journal:
- The Journal of Agricultural Science / Volume 131 / Issue 4 / December 1998
- Published online by Cambridge University Press:
- 01 December 1998, pp. 395-407
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Amounts of spring nitrogen (N) fertilizer (0–240 kg/ha), combined with three timing treatments (single, divided early or divided late), were tested at 14 sites in England and Wales between 1984 and 1988 to determine the optimum fertilizer N requirement for winter oats. The trials were superimposed on commercial crops of the cultivars Pennal (9 sites) or Peniarth (5 sites). Optimum amounts of N ranged from nil to 202 kg/ha (mean 119) and optimum yields varied between 5·8 and 9·9 t/ha (mean 7·3). Much (c. 60%) of the inter-site variation in N optimum was explained by differences in soil N supply, as indicated by N offtake in the grain at nil applied N. Mean yield differences between single and early (+0·08 t/ha) or late (−0·04 t/ha) divided dressings were slight, although significant (P<0·05) but inconsistent yield effects were obtained from early N at two sites and late N at three sites.
Lodging occurred at 11 of the 12 sites where lodging scores were recorded and always increased significantly (P<0·05) with applied N. The amount of crop lodging at N optimum was, on an area basis, <50% at nine of the sites. The overall extent of site lodging was also influenced by soil N fertility and hence inversely related to N optimum. However, multiple regression, using site lodging as well as soil N supply, only accounted for slightly more (65%) of the variation in N optimum, which suggests that lodging was not a major limiting factor. Lodging was unexpectedly less from early N (mean 43%), but more from late N (53%) divided dressings, compared with a single N dressing (49%). Early N reduced lodging significantly (P<0·05) at four sites, although the actual reduction was only large at one site where early N also increased yield significantly (+0·57 t/ha).
Grain N concentrations increased significantly (P<0·05) with applied N, on average by 0·12% per 40 kg/ha N increment. Timing effects on grain N concentration were very small, with mean values of 1·94, 1·91 and 1·96%N respectively from single, early and late divided dressings. Apparent recovery in grain of fertilizer N at the optimum amount ranged from 13 to 57% (mean 37), with better N recovery at the more yield-responsive sites. Changes in mean grain weight due to the amount and timing of fertilizer N were small, with an average reduction of 0·6 mg/grain per 40 kg/ha N applied. The adverse effects of N fertilizer on grain quality were slight and unlikely to have commercial significance. The agronomic implications of these results on the N fertilization of winter oats are discussed.
The response to fertilizer nitrogen of cereals grown on sandy soils
- J. WEBB, F. M. SEENEY, R. SYLVESTER-BRADLEY
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- Journal:
- The Journal of Agricultural Science / Volume 130 / Issue 3 / May 1998
- Published online by Cambridge University Press:
- 01 May 1998, pp. 271-286
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The responses to fertilizer N of winter wheat and winter barley grown on sandy soils were measured in 74 experiments in England from 1991 to 1994. A series of curves was fitted to the data from each of the experiments to determine which best described the yield response to fertilizer N. The linear plus exponential model, adopted for data from a range of other soil types, with the rate parameter (r) determined for each experiment, proved to be the most satisfactory for these data. The median value of r at 0·987 was less than has usually been determined for other soil types, and was reduced by increasing moisture stress in June, suggesting that the reduced efficiency with which recovered N produces assimilate is partly a result of moisture stress. The model produced a mean Nopt of 143 kg/ha following cereals.
Soil N supply in spring (SNSs) was small at c. 45 kg/ha and commensurate with a large requirement for fertilizer N. Apparent fertilizer recovery (AFR) at 0·70 was greater than that previously measured on clay or chalk soils, suggesting that AFR was not restricted by lack of soil moisture. The larger AFR is considered to be a consequence of more rapid remobilization of fertilizer N in these sandy soils. The greater recovery of fertilizer N reduced the optimum requirement for fertilizer N. Nitrogen harvest index (NHI) was decreased from 0·76 to 0·70 as fertilizer N increased from 0 to 300 kg/ha, whereas dry matter harvest index (HI) decreased from 0·53 to 0·50. The economic optimum requirement for fertilizer N, at 143 kg/ha, was less than reported for other soil types.
The increase in grain yield from applied fertilizer N was less in these experiments than in those reported on other soil types in the UK. However, this overall observation masks two counterbalancing differences. Fertilizer N was recovered more efficiently on these soils; the recovered fertilizer N was used with similar efficiency to produce grain dry matter. The explanation proposed is that on these soils a large proportion of soil water is readily available to crops, and this was taken up rapidly in May accompanied by fertilizer N. However, shortage of water in June restricted the ability of the crop to produce assimilate from fertilizer N applications >c. 150 kg/ha.
Evidence for differences between winter wheat cultivars in acquisition of soil mineral nitrogen and uptake and utilization of applied fertilizer nitrogen
- M. J. FOULKES, R. SYLVESTER-BRADLEY, R. K. SCOTT
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- Journal:
- The Journal of Agricultural Science / Volume 130 / Issue 1 / February 1998
- Published online by Cambridge University Press:
- 01 February 1998, pp. 29-44
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The response of cultivars to applied nitrogen was examined in 11 seasons, 1982–92, in two experiments per year, normally testing seven cultivars at seven rates of fertilizer nitrogen. In all, 27 cultivars were tested in 22 experiments throughout Nottinghamshire, Lincolnshire, Northamptonshire and Suffolk. Cultivars ranged in their date of introduction from Maris Huntsman (1969) to Hereward (1988). For each cultivar in each experiment, the economic optimum yield (Yopt), the amount of fertilizer N needed to produce it (Nopt), the grain %N at Nopt, the offtake of N in the grain at nil N (Noff(N0)) and Nopt (Noff(opt)) and the estimated recovery of fertilizer in the grain at Nopt (AFRopt) were estimated by fitting linear plus exponential curves to data for grain yield and two-straight-line models to data for grain N offtake. From cross-site analysis, normalized cultivar means were calculated for each variate. Over the 20-year period relating to the cultivars in the trial, the contribution of new genotypes to grain yield improvement was 1·92 t/ha, Yopt increasing by 96 kg/ha per year. There was no change in grain %N at Nopt. The effect of changes through breeding from 1969 to 1988 was to increase Noff(opt) by 42 kg/ha (2·1 kg/ha per year), that was associated with a decrease in Noff(N0) (equivalent of soil N offtake) of 15 kg/ha (0·77 kg/ha per year). Part of the increased requirement for fertilizer N was fulfilled by an increase in AFRopt of 18% over the 20-year period. The net effect was for Nopt itself to increase by 56 kg/ha (2·8 kg/ha per year). Since survey evidence indicates no general increase in N use on wheat by farmers since the mid-1980s, it appears that current fertilizer use by farmers may be underestimating the requirement for N now. Alternatively in previous years N requirements may have been overestimated. The change in N available for loss to the environment, from the balance of grain Noff(opt) and Nopt, was from 11 kg N/ha in 1969 compared to 25 kg N/ha in 1988. It seems possible that the potential increase in nitrate levels in groundwater associated with plant type may not have been realised because farmers have conserved the amount of N they use.
Prediction of leaf and internode development in wheat
- R. M. WEIGHTMAN, E. J. M. KIRBY, R. SYLVESTER-BRADLEY, R. K. SCOTT, R. W. CLARE, A. GILLETT
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- Journal:
- The Journal of Agricultural Science / Volume 129 / Issue 4 / December 1997
- Published online by Cambridge University Press:
- 01 December 1997, pp. 385-396
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Functions which predict rate of leaf emergence and final number of leaves, used in a model to predict the date at which growth stages occur, were tested in an experiment on winter wheat cv. Mercia grown with standardized husbandry at six sites in 1992/93, 1993/94 and 1994/95. A study of the number of detectable nodes on the culm and leaf length was also made.
The predicted rate of leaf emergence was mostly within 5% of the observed value. The difference between observed and predicted final number of leaves was mostly less than half a leaf but suspected errors in leaf counts resulted in some differences of more than two leaves.
Variable extension of the basal internode impaired confidence in the detection of nodes. The mean number of detectable nodes differed significantly among sites and between seasons from 3·7 to 4·8 but could not be related to sowing date or final number of leaves. Further information on factors affecting extension of the basal internode is desirable to standardize node detection and improve prediction of culm leaf appearance.
Culm leaves showed successively longer laminae up to the penultimate leaf. There was a significant relationship between length of the flag leaf and the final number of leaves, but it was positive in 1993/94 and negative in 1994/95. This may have been due to greater water stress in 1994/95.
The effects of site and season on the fate of nitrogen residues from root crops grown on sandy soils
- J. WEBB, R. SYLVESTER-BRADLEY, F. M. SEENEY
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- Journal:
- The Journal of Agricultural Science / Volume 128 / Issue 4 / June 1997
- Published online by Cambridge University Press:
- 01 June 1997, pp. 445-460
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In 74 experiments carried out in England from 1990 to 1994, cereal test crops were grown on sandy soils prone to nitrate leaching, following cereals, sugarbeet and potatoes. Measurements were made of the effects of the previous crops on soil mineral N, and on N recovery by the cereal test crop.
Soil N supply in autumn (SNSa) was greater following potatoes (c. 100 kg/ha N) than following sugarbeet or cereals (c. 60 kg/ha N). However when potato crops to which organic manures had been applied were excluded, mean SNSa after potatoes was only c. 60 kg/ha. Soil N supply in spring (SNSs) following sugarbeet and potatoes was similar and at c. 56 kg/ha, c. 10 kg/ha greater than following cereals. Seasonal differences in SNSs were related to excess winter rainfall and soil water-holding capacity. Modelled leaching losses gave good agreement with overwinter changes in SNS (r=0·87), although SNSs was usually greater than predicted by the model. This discrepancy was considered to be due to overwinter mineralization, which was estimated from the intercept of the regression lines to be c. 40 kg/ha following cereals and potatoes, and c. 50 kg/ha following sugarbeet.
Apparent net mineralization (AM) of N during the test crop growing season was c. 37, 53 and 63 kg/ha following cereals, sugarbeet and potatoes respectively. However, AM was c. 24 kg/ha N greater if the preceding potato crop had been given organic manures, but there was no difference in AM following manured and unmanured sugarbeet crops.
Nitrogen offtake by the cereal test crop without fertilizer N (NoffN0) was c. 15·20 kg/ha greater following potatoes and sugarbeet than following cereals. The greater N offtake following potatoes is considered to be due to mineralization of organic manures applied to the potato crop, while the effect following sugarbeet appears to be due to mineralization of sugarbeet residues. At harvest, SMN was c. 38 kg/ha and similar for all three previous crops. It is concluded that mineralization of sugarbeet residues has taken place more quickly on these sandy soils than previously reported on soils of greater clay content. Only potatoes grown with organic manures leave greater N residues than cereals.