ABRUÑA, F. and J. VICENTE-CHANDLER 1955 - Organic matter activity of some typical soils of Puerto Rico. Journ. Agric. Univ. Puerto Rico, 39 (2): 65-76.
ABRUÑA, F., J. VICENTE-CHANDLER, R.W. PEARSON and S. SILVA 1970 - Crop Response to Soil Acidity Factors in Ultisols and Oxisols: I. Tabacco. Soil Sc. Soc. Am. Proc. 34: 629-634.
AHN, P.M. 1970 - West African Soils. Oxford University Press, 332 pp., London.
AHN, P. 1972 - Contribution to the knowledge of Ghana Forest soils. Doctoral Thesis Rijksuniversiteit, Ghent, Belgium.
AGARWALL, A.S., B.R. SINGH and Y. KANEHIRO 1971 - Soil Nitrogen and Carbon Mineralization affected by drying - rewetting cycles. Soil Sc. Soc. Am. Proc. 35: 96-100.
AHMAD, S. and C.E. DAVIS 1970 - Forms of K. fertilizers and soil moisture content on potassium status of a Trinidad soil. Soil Sci. 109: 121-126.
ATKINSON, R.J., A.M. POSNER and J.P. QUIRK 1967 - Adsorption of potential determining ions at the ferric oxide-aqueous electrolyte interface. J. Phys. Chem. 71: 550-558.
BARREIRA-PEREIRA, F. and J. DE SOUZA-RODRIGUES 1971 - Posibilidades Agro-climáticas do Municipio de Altamira (Pará). Escola de Agronomía da Amazônia. Boletim n° 1, 46 pp. Belém-Pará, Brazil.
BARTHOLOMEW, W.V. 1972 - Soil Nitrogen and organic Matter. IN: Soils of the humid tropics: 63-81. National Academy of Sciences. Washington D.C.
BARTHOLOMEW, W.V. 1972 - Soil Nitrogen, Supply processes and crop requirements. Technical Bulletin no 6, 78 pp., International Soil Fertility Program. North Carolina State University, Raleigh U.S.A.
BARTHOLOMEW, W.V., J. MEYER and H. LAUDELOUT 1953 - Mineral Nutrient Immobilization under forest and grass fallow in the Yangambi (Belgian Congo) Region. Publication INEAC, série scientifique no 57, 27 pp. Bruxelles.
BAVER, L.D., W.H. GARDNER and W.R. GARDNER 1972 - Soil Physics. John Wiley and Sons, 4th ed., 498 pp., New York.
BECKING, J.H. 1961 - Studies on nitrogen-fixing bacteria of the genus Beijerinckia. I. Geographical and ecological distribution in soils. Plant and Soil 14, 49-81.
BENAVIDES, S.T. 1963 - Distribution of Native Phosphorus and Phosphorus Sorption Capacity of Some Tropical Soils of Colombia. Master of Science Thesis, 103 pp., Oklahoma State University, U.S.A.
BENNEMA, J., A. JONGARIUS and R.C. LEMOS 1970 - Micromorphology of some oxic and argillic horizons in south Brazil in relation to weathering sequence. Geoderma 4: 333-355.
BERTONI, J. 1966 - O Plantíc a o Preparo do Solo am Contôrno e as Perdas por erosão. I. Congreso Panamericano de Conservacão do Solo Proceedings, 101-104.
BOSHOFF, W.H. and G. HILL 1969 - The Comparative value of pro-ploughing cultivations for simplifying seedbed preparations. E. Afr. agric. For. J. 34, 457-460.
BOUCHARD, L. and G. RAKOTOARIMANANA 1970 - Study on the development of structure in lateritic soil under various cultural treatments in relation to the return of crop residues. Agron. Trop., Paris 25, 574-588.
BOUGHEY, A.S., P.E. MUNRO, J. MEIKLEJOHN et al. 1964 - Antibiotic reaction between African savanna species. Nature, London 203, 1302-1303.
BOYE, P. 1962 - Nutrition minérale et carence potassique du palmier à huile. Conf. N.U, Applic. Sci. Techn. Régions peu Développées. C. 3-1.
BOYER, J. 1956 - Quelques critères dans le choix d'un sol à sisal en Oubangi - Chari. 6° Congr. Int. Sc. Sol. 4: 347-351, Paris.
BOYER, J. 1970 - Essai de synthèse des connaissances acquises sur les facteurs de fertilité des sols en Afrique Intertropicale Francophone. ORSTOM, texte polycopié, 175 pp., Paris.
BOYER, J. 1972 - Soil Potassium. IN: Soils of the humid tropics, pp. 102-135. National Academy of Sciences, Washington.
BOYER, Ph. 1971 - Les différents aspects de l'action des termites sur les sols tropicaux. IN: P. PESSON. La vie dans les sols: 281-334. Gauthier-Villars Editeur Paris, France.
BREMNER, J.M. and K. SHAN 1958 - Denitrification in Soils. I. Methods of Investigation. J. Agr. Sci. 51: 22-39.
BRITTO, D.P.P. de S., A.F. DE CASTRO, W. MENDES, A. JACCOUD, D.P. RAMOS and F.A. COSTA 1971 - Estudo das reacoes a micronutrientes en latossolo vermelho-escuro sob vegetacâo de cerrado. Pesq. agropec. bras. Sér. Agron., 6: 17-22.
BROWN, M.E., R.M. JACKSON and S.K. BURLINGHAM 1964 - Studies on Azotobacter species in soil. III. Populations of Azotobacter in the rhizosphere and effects of artificial inoculation. Plant and Soil 17: 320-332.
BURRIS, R.H. 1969 - Progress in the biochemistry of nitrogen fixation. Proc. Royal Soc. London 8, 172: 339-354.
CARNEIRO, A.M. and J. DOBEREINER 1968 - Sobrevivência de Bacterias Assimbioticas fixadoras de N na Rhizosfera do Sorgo. Pesq. Ag. Bras. 3: 151-157.
CATANI, R.A. and J.R. GALLO 1955 - Avaliação da exigência em calcário dos solos do estado de Sâo Paulo, mediante correlaçâo entre o pH e a porcentagem de saturaçâo em bases. Rev. da Agricultura, Piracicaba 30: 49-60.
CATANI, R.A. and N.A. GLORIA 1964 - Evaluation of the Capacity of P fixation by the Soil through the Isotopic Exchange Using p32. An. Esc. Sup. Agr. L. de Queiroz, Vol. XXI: 230-237.
CATE, R.B.Jr. and L.A. NELSON 1965 - A rapid method for correlation of soil test analyses with plant response data. Techn. Bull. n° 1, International soil testing series, North Carolina State University Agricultural, Experiment Station, Raleigh, U.S.A.
CHACON, S.O. 1968 - Effect of lime and Mo on the yield of soya beans and groundnuts. Oriente agrop. 1, 11-22.
CIAT 1972 - (Centro International de Agricultura Tropical). Annual Report 1971. Ciat, Apartado aéreo 67-13, Cali, Colombia.
COMBEAU, A. 1965 - Variations saisonnères de la stabilité structurale en région tempérés. Comparaison avec la zone tropicale. Cahiers ORSTOM, série pédologie 1965, III (2): 123-135.
COMBEAU, A. et G. MONNIER 1961 - Méthode d'étude de la stabilité structurale. Application aux sols tropicaux. Sols Africains 1961, 6 (1): 5-62.
COMBEAU, A. et P. QUANTIN 1963 - Observations sur les variations dans le temps de la stabilité structurale des sols en région tropicale. Cahiers ORSTOM 1963, Série Pédologie 3, 17-26.
COMMISSÃO DE SOLOS 1960 - Levantamento de Reconhecimento dos solos do Estado de São Paulo. Boletim n° 12 do Serviço Nacional de Pesquisas Agronômicas, Ministerio de Agricultura, Rio de Janeiro, Brazil.
CORNFORTH, I.S. and J.B. DAVIS 1968 - Nitrogen Transformations in Tropical Soils; I. The Mineralization of Nitrogen - Rich Organic Materials added to Soil. Trop. Agric. 45(3): 211-221.
DABIN, B. 1967 - Sur une méthode d'analyse du phosphore dans les sols tropicaux. Colloque sur la fertilité des sols tropicaux, Tananarive. 1: 99-115
DAGG, M. and MACARTNEY, J.C. 1968 - The agronomic efficiency of the NIAE tied ridge system of Cultivation. Exp. Agric. 4, 279-294.
DE FREITAS, L.M.M., A.C. McCLUNG and W.L. LOTT 1960 - Field Studies on Fertility Problems of two Brazilean Campos Cerrados 1958-1959. IRI Bull. 21 New York, U.S.A.
DE FREITAS, L.M.M., P.F. PRATT and L. VETTORI 1968 - Testes rápidos para estimar as necesidades em calcarío de alguna solos de São Paulo. Pesq. agropec. bras. 3: 159-164.
DE MARTONNE, E. 1957 - Traité de Géographie Physique. Armand Colin, Paris.
DOBEREINER, J. 1969 - Nonsybiotic Nitrogen Fixation in Tropical Soils. IN: Biology and Ecology of Nitrogen. Proceedings of a Conference National Academy of Sciences, Washington D.C.
DOBEREINER, J. 1970 - Further research on Azotobacter paspali and its variety specific occurrence in the Rhizosphere of Paspalum notatum Flügge. Zentralbl. (in press)
DOBEREINER, J. 1970 - Personal Communication. Rio de Janeiro, Brazil.
DOMMERGUES, Y. 1962 - (A contribution to microbial dynamics in soils of semi-arid and dry tropical regions. I.) Ann. agron. Paris 13, 265-324.
DOMMERGUES, Y. 1962 - (A contribution to microbial dynamics in soils of semi-arid and dry tropical regions. II.) Ann. agron. Paris 13, 391-468.
DOMMERGUES, Y. and F. MANGENOT 1970 - Ecologie microbienne. Masson, 796 pp., 180 fig., 101 tables, Paris, France.
DROSDOFF, M. 1972 - Soil Micronutrients. IN: Soils of the humid tropics, pp. 150-162. National Academy of Sciences, Washington.
ENWEZOR, W.O. and A.W. MOORE 1966 - Phosphorus status of some Nigerian Soils. Soil Sc. 102(5): 322-328.
FAO 1970 - Soil Resources, Development and Conservation Service, Land and Water Development Division, Key to Soil Units, 16 pp., Rome.
FORESTIER, J. 1964 - Relations entre l'alimentation du Coffea Robusta et les caractéristiques analytiques des sols. Café, Cacao, Thé 8 (2): 89-112.
FOX, L.R, 1973 - Examples of anion and cation adsorption by soils of tropical America. Mimeo, 9 pp., University of Hawaii, Honolulu, Hawaii (U.S.A.)
FOX, L.R., D.L. PLUCKNETT and A.S. WHITNEY 1968 - Phosphate requirements of Hawaiian latosols and residual effects of fertilizer phosphorus. 9th Int. Cong. Soil Sci. 2: 302-310.
FRANKART, R. 1960 - Carte des sols et de la végétation du Congo Belge et du Ruanda-Burundi: 14: UELE. Notice explicative 128 pp. Publication INEAC, Bruxelles.
FRANKART, R. and J. CROEGAERT 1959 - Contribution à l'étude de la nutrition minérale du caféier Robusta en Uélé. Publ. INEAC sér. sci. n° 80, 107 pp. Bruxelles.
GREENLAND, D.J. 1958 - Nitrate fluctuations in tropical soils. J. agric. Sci. 50, 82-92.
GREENLAND, D.J. and P.H. NYE 1959 - Increases in the carbon and nitrogen contents of tropical soils under natural fallows. J. Soil Sci. 10: 284-299.
GREENLAND, D.J. 1962 - Denitrification in some tropical soils. J. agric. Sci. 58, 277-233.
GREENLAND, D.J. 1972 - Biological and Organic Aspects of Plant Nutrition in relation to needed research on tropical soils. Mimeo. 13 pp.
HENIN, S., O. ROBICHET and A. JONGERIUS 1955 - Principes pour l'évaluation de la stabilité de la structure du sol, Ann. Agron. 6: 537-557.
IGUE, K. and J.R. GALLO 1960 - Zinc deficiency of Corn in São Paulo. IBEC Research Institute Bulletin 20, New York.
IRI Research Institute 1967 - Semi Annual Report. June 1967. Mimeographed 95 pp., 1 Rockefeller Plaza, New York 10020, U.S.A.
IRI Research Institute 1968 - Semi-Annual Report, June 1968. Mimeographed 63 pp., 1 Rockefeller Plaza, New-York 10020, U.S.A.
IRI Research Institute 1969 - Progress Report 16 pp., IRI Research Institute, Inc. 1 Rockefeller Plaza, New York, N.Y. 10020, U.S.A.
JENSEN, H.L. 1965 - Non-symbiotic nitrogen fixation. IN: Bartholomew, W.V. and F.E. Clark, editors: Soil Nitrogen pp. 440-485. Am. Soc. Agron. Monograph n° 10. Madison, Wisconsin, U.S.A.
JORGE, J.A. and J. VALADARES 1969 - Formas de Fósforo em solos do Estado de São Paulo. Bragantia 28: 23-30.
JULIA, H. 1962 - La station de Sibiti. Oléagineux 17: 356-360.
JURION, F. and J. HENRY 1969 - Can Primitive farming be modernized ? Publication INEAC, Hors Série 457 pp., Bruxelles.
KASS, D.C. 1970 - Sources of N in tropical Environments with special reference to the relationship between Paspalum Notatum Flügge and Azotobacter Paspali Döbereiner. Thesis Cornell University, Ithaca, N.Y., U.S.A.
KASS, D.C. and M. DROSDOFF 1970 - Sources of Nitrogen in Tropical Environments Agronomy Mimec. 70-9, Cornell University, Ithaca, N.Y.
KASS, D.L., DROSDOFF, M. and M. ALEXANDER 1971 - Nitrogen fixation by Azotobacter paspali in association with Bahia grass (Paspalum notatum). Proc. Soil Sc. Soc. Amer. 35, 286-289.
KUPPER A., F. GROHMANN and H. GARGANTINI 1953 - Movimento de Ions, NO3, NH4, K e PO4 em Solos Massapé, Roxa Misturada e Arenito Baurú. Instituto Agronômico de Campinas, Bôletim n° 34, 9 pp. Brazil.
LAUDELOUT, H. 1959 - Principes de l'Utilisation des engrais minéraux au Congo Belge. Agricultura 7: 451-457, Leuven, Belgium.
LATHWELL, D.J., H. D. DUBEY and R.H. FOX 1972 - Nitrogen supplying Power of some Tropical Soils of Puerto Rico and Methods of its Evaluation. Agronomy Journal 64: 763-766.
LAUDELOUT, H. 1961 - Dynamics of Tropical Soils in Relation to their Fallowing Techniques. FAO, Publication 11266/E, Rome, Italy.
LE BUANEC, J. 1970 - Personal Communication IN: J. Boyer. Essai de synthèse des connaissances acquises sur les facteurs de fertilité des sols en Afrique Intertropicale. Francophone. ORSTOM, mineographed 175 pp., Paris.
LUGO LOPEZ, M.A., J. Jr. JUAREZ and J.A. BONNET 1968 - Relative infiltration rate of Puerto Rican soils. J. Agric, Univ. Puerto Rico 52(3): 233-240.
MARTIN, G. 1969 - Some boron deficiency symptoms in oil palms. Aléagineux 24, 613-614.
MASCARENHAS, H.A.A., E.S. MIYASAKA, G. FREIRE, E. SORDI and S. LOPES 1967 - Adubação da Soja. V. Efeitos da Inoculacao das sementes com Rhizobium e da subsequente "Peletização" com pasta de carbonato de Calciu na ausencia e na presença da Calagem e da Adubação nitrogenada Bragantia 26: 143-154.
McCLUNG, A.C., L.M.M. DE FREITAS, D.S. MIDDELSEM and W.L. LOTT 1961 - Cotton Fertilization on Campo Cerrado Soils, State of São Paulo, Brazil. IBEC Research Institute Bull. n° 27.
McCLUNG, A.C. and L.R. QUINN 1959 - Sulfur and Phosphorus Responses of Batatais Grass (Paspalum Notatum). IBEC Research Institute Bull. n° l8.
McCLUNG, A.C., L.M. MARTINS and L. DE FREITAS 1959 - Sulfur deficiencies in soils from Brazilean campos. Ecology 40(2): 3l5-317
MEDOALF, J.C. 1956 - Preliminary Study on Mulching Young Coffee in Brazil. IBEC Research Institute 30 Rockefeller Plaza, New York 20, Bull. 12.
MEDINA, H.P. and F. GROHMANN 1966 - Disponibilidade de Agua em Alguns Solos do Cerrado. Bragantia 25(6): 65-76.
MEIKLEJOHN, J. 1962 - Microbiology of the nitrogen cycle in some Ghana soils. Emp. J. Exp. Agric. 30, 115-126.
MEYER, J.A. 1959 - Fluctuations de l’N minéral dans les sols eous cultures vivrières. Comptes Rendus de la III° Conférence Interafricaine des sols 1: 517-524. Dalaba. CCTA Publications Bureau, Watergate House, Yorks Buildings, London, W.C. 2.
MIDDELBURG, M.A. 1950 - Donnan evenwichten en de samenstelling van tabaksas. Landbouwkunding tijdschrijft, 62: 306-311.
MIDDELSEN, D.S., L.M.M. DE FREITAS and A.C. McCLUNG 1963 - Effects of Liming and Fertilizing Cotton, Corn and Soybeans on Campo Cerrado Soils, State of São Paulo, Brazil. IRI Research Institute, Bull. 29.
MISHUTIN, E.H. 1967 - Soil Microbiology in the USSR (1917-1967). Microbiology 36: 664-685.
MIYASAKA, S., S.A. PAES DE CAMARGO, R. INFORZATO and T. IGUE 1966 - Efeitos da Cobertura e da Incorporaçao do Solo, immediatamente antes do Plantio, de diferentes formas de Matéria Orgânica não decomposta na cultura do Feijoéiro. Bragantia. 25: 349-363.
MOITY, M. 1954 - La carence en zinc sur bananier. Fruits 9(8): 354.
MOREL, R. and P. QUANTIN 1964 - (Fallowing and soil regeneration under the Sudan-Guinea climate in Central Africa). Agron. trop. Paris 19, 105-136.
MOULINIER, H. 1962 - Contribution à l'étude agronomique des sols de basse Côte d'Ivoire. Bull. Inst. Français Café et Cacao, (3), 1962.
MOURA, W. 1968 - Characterization of the Physical, Chemical and Micromorphological Changes engendered by the Cultivation of a Soil in the Triangulo of Minas Gerais, Brazil. Thesis, NCSU, Raleigh 55 pp., mimeographed.
MUZILLI, O., R.E. KALCKMANN and F.G. MUNHOZ 1969 - Estudo da Correção da Acidez dos Solos do Estado do Parana. I. Determinação de Curvas de Neutralização em Latossols Roxo do Oeste. Rev. Esc. Agron. Veterinaria, 5: 25-33. Universidad Federal do Paraná, Curitiba, Paraná, Brazil.
NEWTON, J.D. and A. SAID 1957 - Molybdenum deficiency in latosols of Java. Nature 180: 1485-1486.
NYE, P., D. CRAIG, N.T. COLEMAN and J.L. RAGLAND 1961 - Ion exchange equilibrium involving aluminium. Soil. Sci. Soc. Amer. Proc. 251 14-17.
NYE, P.H. and GREENLAND, D.J. 1960 - The Soil under Shifting Cultivation. Commonw. Bur. Soils Tech. Comm. 51, pp. 156.
OLIVEIRA, V., A.E. LUDWICK and M.T. BEATTY 1971 - Potassium removed from some southern Brazilian soils by exhaustive cropping and chemical extraction methods. SSSAP 35(5): 763-767.
OLSON, R.A. and O.P. ENGELSTAD 1972 - Soil Phosphorus and Sulfur. IN: Soils of the Humid Tropics, pp. 82-101. National Academy of Sciences Washington D.C.
OLMOS, J.I.L., C.A. SCOTTI, O. MUZILLI and L. TURKIEWICZ 1971 - Estudo comparativo da productividade de alguns solos álicos e não álicos do estado do Paraná. Boletim da Universidade Federal do Paraná. Agronomia n° 6.
PARKER, C.A. 1954 - Effect of oxygen on the fixation of nitrogen by Azotobacter. Nature 173: 780.
PEARSON, R.W. 1966 - Soil Environment and Root Development. IN: Plant Environment and Efficient Water Use ASA and SSA Madison, Wisconsin.
PEREIRA, H.C. 1954 - Soil Structure criteria for tropical crops. Trans. V. Int. Crop Soil Sci. II: 59-64.
PEREIRA, H.C. 1954 - The assessment of structure in tropical soils. J. Agr. Sci., 45: 401-410.
PEREIRA, H.C., E.M. CHENERY and W.R. MILLS 1954 - The transient effects of grasses on the structure of tropical soils. Emp. J. Exp. Agric., 22: 148-160.
PEREIRA, H.C., P.H. HOSEGOOD and M. DAGG 1967 - Effects of tied ridges, terraces and grass leys on a lateritic soil in Kenya. Exp. Agric. 3, 89-98.
PEREIRA, H.C., R.A. WOOD and H.W. BRZOSTOWSKI et al. 1958 - Water conservation by fallowing in semi-arid tropical East Africa. Emp. J. exp. Agric. 26, 213-228.
PEREZ-ESCOLAR, R. and M.A. LUGO-LOPEZ 1968 - Nature of aggregation in two tropical soils of Puerto Rico. 52(3): 227-32.
PRAMANIX, B.N. and A.N. MISRA 1955 - Effect of continuous manuring with artificial fertilizers on Azotobacter and soil fertility. Indian J. Agric. Soi. 25, 1-13.
PRATT, P.F. 1965 - Relatorio Final. Instituto de Pesquisas IRI, New York, São Paulo, 84 pp.
PRATT, P.F. 1966 - Report of Consultancy. Instituto de Pesquisas IRI. Mimeo. 17 pp., São Paulo, Brazil.
PRATT, P.F. and R. ALVAHYDO 1966 - Cation-Exchange Characteristics of Soils of São Paulo, Brazil. IRI Research Institute, Ino. Bull. 31.
ROCHE, P., J. VELLY and B. JOLIST 1959 - Utilisation du diagnostic foliaire de l'arachide dans le secteur de conservation des sols vallée - témoin Lao Alaotra. Essai d'interprétation des analyses foliaires effectuées sur arachides de 1954 à 1957. Agronomie Tropical 14: 580-584.
ROOSE, E., J. GODEFROY and M. MULLER 1970 - Estimation des pertes par lixiviation des éléments fertilisants dans un sol de bananaraie de basse Côte d'Ivoire. Fruits 25: 403-420.
RUSSELL, E.W. 1971 - Soil Structure; its maintenance and improvement J. Soil Sci. 22, 137-151.
SANCHEZ, P.A. 1972 - Class handouts for lectures on Soils under shifting cultivation. Soil Science Department, North Carolina State University, Raleigh, U.S.A.
SAUCHELLI, V. 1969 - Trace elements in agriculture. Van Norstrand Reinhold Company, 248 pp. New York.
SAUNDER, D.H. and P.M. GRANT 1962 - Rate of mineralisation of organic matter in cultivated Rhodesian soils. Int. Soil Conf. N.Z., 235-239.
SCHUFFELEN, A.C. and H.A. MIDDELBURG 1954 - Structural deterioration of lateritic soils through liming. Trans. V I.C.S.S. 2, 158-165.
SHARMA, M.L. and G. UEHARA 1969 - Influence of Soil Structure on Water Relations in Low Humic Latosols. I. Water retention. II. Water movement. SSAP 32(6): 765-774.
SMITH, R.M. and F. ABRUÑA 1955 - Soil and Water Conservation Research in Puerto Rico 1938-1947. University of Puerto Rico, Agricultural Experiment Station, Bulletin 124, 51 pp.
SMITH, R.M. and C.F. CERNUDA 1951 - Some applications of Water-drop stability testing to tropical soils of Puerto-Rico. Soil Science 71(5): 337-345.
STANTON, D.A. and BURGER 1967 - Availability to plants of Zinc sorbed by soil and hydrous iron oxides. Geoderma 1: 13-17.
STEWART, W.D.P. 1966 - Nitrogen fixation in Plants. Athlone Press, London. 168 pp.
STEWART, W.D.P. 1969 - Biological and Ecological aspects of N fixation by free living organisms. Proc. Roy. Soc. London B, 172: 367-388.
STOBBS, T.H. 1969 - The effect of grazing resting land upon subsequent arable crop yields. E. Afr. Agr. For. J. 35, 28-32.
SYS, C. 1971 - De Bodems van de tropisohe, subtropische en ariede gebieden. Mimeographed 128 pp., Rijksuniversiteit, Gent, Belgium.
SYS, C. 1972 - Caractérisation morphologique et physico-chimique de profile types de l'Afrique centrale. Publication INEAC, 497 pp., Bruxelles.
THORNTHWAITE, C.W. and J.R. MATHER 1955 - The water Balance. Drexel Institute of Technology, Publications in Climatology, 8(1): 104.
TURENNE, J.F. 1969 - Clearing and Burning as Soil Preparation Modifications of Physic and Chemic Characters of the upper Soil Horizons. ORSTOM, Centre de Cayenne, Texte Polycopie. 7e Congrès Caribbean Food Crops Society.
USHARA, G., L.D. SWINDALE and R.C. Jones 1972 - Mineralogy and Behaviour of Tropical Soils. Mimeo. 13 pp., Seminar on Tropical Soil Research, Ibadan.
U.S.D.A. 1960 - Soil Classification. A comprehensive system. 7th Approximation. Washington D.C., U.S.A.
U.S.D.A. 1970 - Selected Chapters from the Unedited Text of the National Cooperative Soil Survey. Washington D.C., U.S.A.
VAN RAIJ, B. and M. PEECH - Electrochemical properties of some oxisols and alfisols of the Tropics. Soil Sc. Soc. Am. Proc. 36(4): 587-592.
VERDADE, DA COSTA, F. 1969 - Importance of Nonsymbiotic Organisms in the Nitrogen Economy of Tropical Soils. IN: Biology and Ecology of Nitrogen, Proceedings of a Conference. National Academy of Sciences Washington D.C.
VETTORI, L. 1948 - Determinação da necessidade de cal dos solos. Bol. 7c., Inst. Quim. Agricola, Rio de Janeiro.
VICENTE-CHANDLER, J. and S. SILVA I960 - Effects of Nitrogen Fertilization and Grass Species on Soil Physical Condition in some Tropical Pastures. J. Agric. Univ. Puerto Rico 44(2): 77-86.
VICENTE-CHANDLER, J., R.C. COSTAS and R.W. PEARSON 1964 - The Intensive Management of tropical Forages in Puerto Rico. Univ. P. Rico Agr. Exp. St. Rio Piedras, Puerto Rico. Bull. 187.
WALTON, P.D. 1962 - The Effect of Ridging on the cotton crop in the Eastern Province of Uganda. Empire Journ. Exper. Agric. 30(117): 63-76.
WESTIN, F.C., J.G. DE BRITO 1969 - Phosphorus fractions of some Venezuelan soils as related to their stage of weathering. Soil Sc. 107, 194-202.
WILSON, H.M. and C.S. WINKELBLECH 1966 - Tillage: Basic Principles and Techniques. Cornell Ext. Bulletin 1176.
WOODRUFF, C.M. 1948 - Testing soils for lime requirement by means of a buffered solution and the glass electrode. Soil Sci. 66: 53-63.
