References

Agboola, A.A., 1978. The influence of organic matter on cowpeas response to N fertilizer. Agron. J., 70: 25-28.
Direct Link  |  

Amberger, A., 2006. Soil Fertility and Plant Nutrition in the Tropics and Subtropics. IFA, IPI, Paris, France.

Chapman, H.D., 1966. Diagnostic Criteria for Plants and Soils. Citrus Resources Centre and Agriculture Experiment Station, California.

Eikan, G.H., 1992. Biological N Fixation Systems in the Tropical Ecosystem: An Overview. IITA, Ibadan, pp: 27-40.

Eshett, E.T., 1990. The Wetland Soils of Nigeria. Properties, Classification and Traditional Landuse Practices. In: Wetlands and Ecotones Studies on Land-water Interactions, Gopal, B., A. Hillbricht-Ilkowska and R.G. Wetzel (Eds.). National Institute of Ecology, New Delhi, pp: 227-244.

Essoka, A.N. and I.E. Esu, 2001. Physical properties of inland valley soils of central Cross River State, Nigeria. Proceedings of the 27th Annual Conference, (AC'01), Soil Science Society, Nigeria, pp: 119-123.

FAO, 1977. Guidelines for Soil Profile Description. 2nd Edn., FAO, Rome, pp: 53.

FAO, 1988. Bio and Organic Fertilizers: Prospects and Progress in Asia. RAPA Publication, Bangkok, Thailand, pp: 78.

FAO, 1974. Soil Map of the World 1: 5,000,000. Vol. 1, FAO, Unesco, Paris, pp: 59.

FAO, 1976. A Framework for land evaluation. Food and Agriculture Organization, Vol. 32, Soils Bulletin No. 32. Rome.

FAO., 1979. Soil survey investigation for irrigation. Soil Bulletin No. 42. FAO, Rome, pp: 188.

FAO/UNESCO, 1988. The Revised Legend of the Soil Map of the World. World Resources Publication, Rome.

Fagbemi, A., S.O. Adjayi and E.M. Ali, 1985. Nutrient distribution in the basement complex soils of the tropical, dry rainforest of southwestern Nigeria: 2. Micronutrients-zinc and copper. Soil Sci., 139: 531-537.

Francis, C.A., R.R. Harwood and J.F. Parr, 1986. The potential for regenerative agriculture in the developing world. Am. J. Alternative Agric., 1: 65-74.
Direct Link  |  

Gichuru, M.P., 2003. Soil fertility management in Africa. A regional perspective. Tropical Soil Biology and Fertility-CIAT.

IFPRI, 1999. Nurturing the soil in sub-saharan Africa. International Food Policy Research Institute, A 2020 Vision for Food, Agricultural and the Environment.

IITA, 1979. Selected Methods for Soil and Plant Analysis. 2nd Edn., International Institute of Tropical Agriculture, Ibadan, Oyo State, Nigeria, Pages: 70.

Ibia, T.O. and E.J. Udo, 1993. Phosphorus forms and fixation capacity of representative soils in Akwa Ibom State of Nigeria. Geoderma, 58: 95-106.

Ibia, T.O., 1995. Inland Swamps of Akwa Ibom State: Their Characteristics, Potentials and Constraints to Development. In: African Soils: Rehabilitation and Management of African Soils for Sustainable Productivity and Environmental Protection, Agboola, A.A. (Ed.). Vol. 28, OAU/STRC, Lagos, Nigeria, pp: 551-561.

Jalloh, M. and G. Anderson, 1986. Integrated Development of Watersheds in Sierra Leone. In: The Wetlands and Rice in Sub-Saharan Africa, Juo, A.S.R. and J.A. Lowe (Eds.). IITA, Ibadan, Nigeria, pp: 275-283.

Klute, A., 1986. Methods of Soil Analysis. 2nd Edn., American Society of Agronomy, Madison, Wisconsin, USA.

Landon, J.R., 1984. Booker Tropical Manual: A Handbook for Soil Survey and Agricultural Land Evaluation in the Tropics and Subtropics. Longman, New York.

Likens, G.E., C.T. Driscoll, D.C. Buso, T.G. Siccama and C.E. Johnson et al., 1994. The biogeochemistry of K at habbard brook. Biogeochemistry, 25: 61-125.
Direct Link  |  

Nigerian Meteorological Services, 1996. Climate data for calabar airport. Lagos, Nigeria.

Obi, M.E., 1984. The wetlands of Nigeria. Proceedings of the 21st Annual Conference of Soil Science Society of Nigeria. Port Harcourt, Nigeria.

Ogban, P.I. and O. Babalola, 2003. Soil characteristics and constraints to crop production in inland valley bottoms in southwestern Nigeria. Agric. Water Manage., 61: 13-28.
Direct Link  |  

Ogban, P.I., 1999. Characterization and management of inland valley bottoms for crop production in southwestern Nigeria. Ph.D. Thesis, Department of Agronomy, University of Ibadan, Nigeria.

Ojanuga, A.G., G. Lekwa and T.A. Okusami, 1996. Distribution, classification and potentials of wetland soils of Nigeria. Monograph No. 2, Soil Science Society of Nigeria, pp: 1-24.

Omoti, U., 2001. Presidential address. Proceedings of the 27th Annual Conference of Soil Science Soceity of Nigeria, Calabar.

Opuwaribo, E.E. and N.O. Isirimah, 1984. Fertility and Management of Wetland Soils in Nigeria. Proceedings 12th Annual Conference of Soil Science Society of Nigeria, Port Harcourt, Nigeria.

Paul, E.A. and F.C. Clark, 1989. Soil Microbiology and Biochemistry. Academic Press Inc., San Diego, California, pp: 406.

Soil Survey Staff, 1990. Keys to Soil Taxonomy. Soil Management Support Services and Technical Monograph 19. 4th Edn., Virginia Polytechnic Institute and State University, Blacksburg, VA., pp: 19.

Sparks, D.L., A.L. Page, P.A. Helmke, R.H. Loeppert and E. Summer et al., 1996. Methods of Soil Analysis. Part 3. Chemical Methods. ASA, SSSA, Madison WI., USA., pp: 1390.

Ukpong, I.E., 2000. Ecological classification of Nigerian mangroves using soil nutrient gradient analysis. Wetlands Ecol. Manage., 8: 263-272.

Uniuyo Consult Ltd, 2003. Soil potentials of Akwa Ibom state: Soils of the coastal zone. Government of Akwa Ibom State, Ministry of Agriculture, Uyo, pp: 116.

Valiela, I. and J.M. Teal, 1974. Nutrient Limitation in Salt Marsh Vegetation. In: Ecology of Halophytes, Reimold, R.J. and W.H. Queen (Eds.). Academic Press, New York, pp: 547-563.

Villapando, R.R. and D.A. Greatz, 2001. Phosphorus absorption and desorption properties of the soil. Spolic horizon from selected Florida spodosols. Soil Sci. Soc. Am. J., 63: 331-339.

Yadav, A.K., S.R. Chaudhuri and M.R. Motsara, 2001. Recent advances in biofertilizer technology. Society for Promotion and Utilization of Resources and Technology, pp: 526.

Zonn, S.V., 1986. Tropical and Subtropical Soil Science. Mir Publishers, Moscow, pp: 442.