References
- Analogidis , D. 2000 . Soil nutrients and crop production , Athens, Greece : Agro Typos SA .
- Bremmer , J. M. 1965 . “ Total nitrogen ” . In In Methods of soil analysis, part 2, ed. C. A. Black et al., 1149–1178 , Madison, Wisc : ASA .
- Bremmer , J. M. and Keeney , D. R. 1966 . Determination and isotope-ratio analysis of different forms of nitrogen in soils, 3: Exchangeable ammonium, nitrate, and nitrite by extraction–distillation methods . Proceedings of the Soil Science Society of America , 30 : 577 – 582 .
- Carrow , R. N. , Stowell , L. , Gelernter , W. , Davis , S. , Duncan , R. R. and Skorulski , J. 2004 . Clarifying soil testing, III: SLAN sufficiency ranges and recommendations . Golf Course Management , 72 : 194 – 198 .
- Cataldo , D. A. , Haroon , M. , Schrader , L. E. and Youngs , V. L. 1975 . Rapid colorimetric determination of nitrate in plant tissue by nitration of salicylic acid . Communications in Soil Science and Plant Analysis , 6 : 71 – 80 .
- CCME . 2007 . Canadian soil quality guidelines for the protection of environmental and human health , Winnipeg : Canadian Council of Ministers of the Environment .
- Hassett , J. J. and Banwart , W. L. 1992 . Soils and their environment , Englewood Cliffs, N.J : Prentice Hall .
- Ilaco , B. V. 1985 . Agricultural compendium, for rural development in the tropics and subtropics , New York : Elsevier .
- Loveland , P. and Webb , J. 2003 . Is there a critical level of organic matter in the agricultural soils of temperate regions: A review . Soil and Tillage Research , 70 : 1 – 18 .
- MAAF . 1988 . Fertilizer recommendations , London : HMSO .
- Makoi , J. H. J. R. and Ndakidemi , P. A. 2008 . Selected chemical properties of soil in the traditional irrigation schemes of the Mbulu district, Tanzania . African Journal of Agricultural Research , 3 : 348 – 356 .
- Marx , E. S. , Hart , J. and Stevens , R. G. 1999 . Soil test interpretation guide (EC 1478 Extension and Station Communications) , Corvallis : Oregon State University .
- Miller , R. H. and Keeney , D. R. 1982 . Methods of soil analysis, part 2 , Madison, Wisc : American Society of Agronomy .
- Ndakidemi , P. A. and Semoka , J. M. R. 2006 . Soil fertility survey in western Usambara, Northern Tanzania Mountains . Pedosphere , 16:237 : 244
- Nelson , D. W. and Sommers , L. E. 1982 . Total carbon, organic carbon, and organic matter. In Method of soil analysis, part 2 , 2nd , Edited by: Page , A. L. 539 – 579 . Madison , Wisc : ASA and SSSA .
- Olsen , S. R. , Cole , C. V. , Watanabe , F. S. and Dean , L. A. 1954 . Estimation of available phosphorous in soils by extraction with sodium bicarbonate (USDA Circular 939). Washington , D.C : U.S. Government Printing Office .
- Panagiotopoulos , L. 1995a . “ Sustainable crop fertilization, review: Potato fertilization ” . In Agriculture crop and animal husbandry , 227 – 231 . Athens , , Greece : Agro Typos SA .
- Panagiotopoulos , L. 1995b . “ Sustainable crop fertilization, review: Cucumber fertilization ” . In Agriculture crop and animal husbandry , 250 – 256 . Athens , , Greece : Agro Typos SA .
- Sanchez , P. A. , Palm , C. A. and Boul , S. W. 2003 . Fertility capability classification: A tool to help assess soil quality in the tropics . Geoderma , 114 : 157 – 185 .
- Schmidt , E. L. 1982 . “ Nitrification in soil ” . In In Nitrogen in agricultural soils , Edited by: Stevenson , F. J. Madison, Wisc : American Society of Agronomy .
- Silanpaa , N. 1982 . Micronutrients and nutrient status of soils: A global study (FAO Soil Bulletin). Rome , Italy : FAO .
- Tilman , G. D. 1984 . Plant dominance along an experimental nutrient gradient . Ecology , 65 : 1445 – 1453 .
- Walkley , A. and Black , I. A. 1934 . An examination of the Degtjareff method for determining organic carbon in soils: Effect of variations in digestion conditions and of inorganic soil constituents . Soil Science , 63 : 251 – 263 .