The effects of strategic nitrogen fertiliser application during the cool season on perennial ryegrass-white clover pastures in the Western Cape Province 1. Soil nitrogen dynamics

References

• Allison , F. E. 1966 . The fate of nitrogen applied in soils . Adv. Agron. , 18 : 219 – 258 .
   Google Scholar
• ANON . 1996 . Verslag van die grondkundige opname van die plaas Elsenburg. Western-Cape : Resource Utilization, Department of Agriculture .
   Google Scholar
• ARC-ISCW . 2004 . Databank Agrometeorology, ARC-Institute for Soil, Climate and Water. Stellenbosch.
   Google Scholar
• Ball , P. R. and Ryden , J. C. 1984 . Nitrogen relationships in intensively managed temperate grasslands . Plant Soil , 76 : 23 – 33 .
   Web of Science ®Google Scholar
• Bessinger , F. 1985 . Methods of Plant Analysis by Autoanalyzer Techniques. Information Bulletin No D-3. Soil and Irrigation Research Institute, Private Bag X79, Pretoria. 0001.
   Google Scholar
• Beyers , C. P. and De , L. 1983 . Bemesting van aangeplante weidings. Winterreën, Spesiale uitgawe No. 5 54 – 59 .
   Google Scholar
• Clarkson , D. T.A. and Warner , A. 1979 . Relationships between root temperature and transport of ammonium and nitrate ions by Italian and perennial ryegrass (Lolium multiflorum Lolium perenne) . Plant Physiol. , 64 : 557 – 561 .
   PubMed Web of Science ®Google Scholar
• Curtis , A. and O'Brien , G. 1994 . Pasture management for dairy farmers. Victorian Department of Agriculture, 166 Wellington Parade, East Melbourne 3002, Victoria, Australia 3 – 57 .
   Google Scholar
• Du Preez , C. C. and Burger , R . 1987a . Laboratory measurements of ammonia volatilization from five nitrogen-containing fertilizers after surface application at different rates on a neutral to alkaline soil . S. Afr. J. Plant Soil , 4 : 17 – 20 . Du.T
   Google Scholar
• Du Preez , C. C. and Burger , R . 1987b . Effect of application methods on ammonia volatilization from soils in a controlled environment . S. Afr. J. Plant Soil , 4 : 57 – 60 . Du.T
   Google Scholar
• Eckard , R. J. 1994 . The nitrogen economy of three irrigated temperate grass pastures with and without clover in Natal. Ph.D Thesis. The University of Natal, Pietermaritzburg. South Africa.
   Google Scholar
• Frame , J. and Boyd , A. G. 1987 . The effect of strategic use of fertiliser nitrogen in spring and/or autumn on the productivity of perennial ryegrass/white clover sward . Grass Forage Sci. , 42 : 429 – 438 .
   Web of Science ®Google Scholar
• Hatch , D. J. and Macduff , J. H. 1991 . Concurrent rates of N2 fixation, nitrate and ammonium uptake by white clover in response to different root temperatures . Ann. Bot. , 67 : 265 – 274 .
   Web of Science ®Google Scholar
• Hutchings , N. J. and Kristensen , I. S. 1995 . Modelling mineral nitrogen accumulation in grazed pasture: Will more nitrogen leach from fertilized grass than unfertilized grass/clover? . Grass Forage Sci. , 50 : 300 – 313 .
   Google Scholar
• Labuschagne , J. 2005 . Nitrogen management strategies on perennial ryegrass-white clover pastures in the Western Cape Province. Ph. D thesis. University of Stellenbosch.
   Google Scholar
• Laidlaw , A. S. 1984 . Quantifying the effect of nitrogen fertiliser applications in spring on white clover content in perennial rye- grass-white clover swards . Grass Forage Sci. , 39 : 317 – 321 .
   Web of Science ®Google Scholar
• McKENZIE , F. R. 1996 . The effect of grazing frequency and intensity on root development of Lolium perenne L. under subtropical conditions . S. Afr. J. Plant Soil , 13 : 22 – 26 .
   Google Scholar
• McKENZIE , F. R. , Ryan , M. J. , Jacobs , J. L. and Kearney , G. 1999 . Effect of rate and time of nitrogen application from autumn to midwinter on perennial ryegrass-white clover dairy pastures in western Victoria. 1. Growth and composition . Aust. J. Agric. Res. , 50 : 1059 – 1065 .
   Google Scholar
• NON-AFFILIATED SOIL ANALYSIS WORK COMMITTEE . 1990 . Handbook of standard soil testing methods for advisory purposes. Soil Science Society of South Africa, Sunnyside, 0132.
   Google Scholar
• Olsen , R. A. and Kurtz , L. T. 1982 . “ Crop nitrogen requirements, utilization and fertilization. ” . In Nitrogen in agricultural soils. Agron. No 22, Madison, Wisconsin. 567. Edited by: Stevenson , F. J.
   Google Scholar
• Ott , R. L. 1998 . An introduction to statistical methods and data analysis. California : Duxbury Press . Belmont
   Google Scholar
• Reid , D. 1984 . The seasonal distribution of nitrogen fertiliser dressings on pure perennial ryegrass swards . J. Agric. Sci. Cam. , 103 : 659 – 669 .
   Google Scholar
• Ridley , A. M. , Simpson , R. J. and White , R. E. 1999 . Nitrate leaching under phalaris, cocksfoot and annual ryegrass pastures and implications for soil acidification . Aust. J. Agric. Res. , 50 : 55 – 63 .
   Google Scholar
• Ryden , J. C. 1985 . “ Denitrification loss from managed grassland. ” . In Denitrification in the Nitrogen Cycle. Plenum Publishing Corporation. Edited by: Goltersman , H. L.
   Google Scholar
• Ryden , J. C. , Ball , P. R. and Garwood , E. A. 1984 . Nitrate leaching from grassland . Nature , 311 : 50 – 53 .
   Web of Science ®Google Scholar
• SAS . 1999 . SAS/STAT User's Guide, Version 8, 1^st printing, Volume 2 Cary , North Carolina : SAS Institute Ine, SAS Campus Drive . 27513
   Google Scholar
• Shapiro , S. S. and Wilk , M. B. 1965 . An analysis of variance test for normality . Biometrika , 52 : 591 – 611 .
   Web of Science ®Google Scholar
• Snedecor , G. W. and Cochran , W. G. 1967 . Statistical Methods. Ames , Iowa : Iowa State University Press . Sixth Ed. The, U.S.A
   Google Scholar
• SOIL CLASSIFICATION WORKING GROUP . 1991 . Soil Classification: A taxonomic system for South Africa. Memoirs on the Agricultural Natural Resources of South Africa Nr. 15. Department of Agricultural Development. Pretoria, South Africa.
   Google Scholar
• Stout , W. I. , Weaver , R. S. and Elwinger , G. F. 2001 . Effects of early season nitrogen on grass-clover swards in the northern USA . Agron. J. , 93 : 1000 – 05 .
   Google Scholar
• Van Der Watt , H. V.H. 1966 . Improved tables and a simplified procedure for soil particle size analysis by the hydrometer method . S. Afr. J. Agric. Sci. , 9 : 911 – 916 .
   Google Scholar
• Whitehead , D. C. 1970 . The role of nitrogen in grassland procductivity. Bulletin, Commonwealth Bureau of Pastures and Field Crops. No 48 Farnhum Royal; Commonwealth Agricultural Bureau.
   Google Scholar
• Whitehead , D. C. , Pain , B. F. and Ryden , J. C. 1986 . Nitrogen in UK Grassland Agriculture . J. Royal Agric. Soc. Eng. , 147 : 190 – 201 .
   Google Scholar
• Wienhold , B. J. and Halvorson , A. D. 1999 . N-mineralization responses to cropping, tillage and N rate in the Northern Great Plains . Soil Sci. Soc. Am. J. , 63 : 192 – 196 .
   Web of Science ®Google Scholar
• Wolfson , M. M. and Tainton , N. M. 2000 . “ The morphology and physiology of the major forage plants. ” . In Pasture management in South Africa. Edited by: Tainton , N. M. Pietermaritzburg : University of Natal Press .
   Google Scholar