02594naa a2200361 a 450000100080000000500110000800800410001910000220006024501070008226000090018950001470019852015460034565000150189165000120190665000150191865000190193365000150195265000120196765000120197965000130199165000090200465300100201365300110202365300130203465300110204765300080205865300150206665300110208165300200209270000210211270000170213377300820215010870332020-06-26       1982    bl uuuu     u00u1 u    #d1 aVELLOSO, A. C. X.  aCapacidade de troca de cátions e adsorção de fosfato de solos sob vegetação de cerrado do Amapá.  c1982  aTítulo em inglês: Cation exchange capacity and phosphate adsortion of soils under cerrado (Savannah) vegetation of Amapá, Amazonian Region.  aRESUMO - Foi estudada, em cinco solos sob vegetacao de cerrado do Territorio Federal do Amapa, a capacidade de troca de cations e de adsorcao de fosfatos. Para a capacidade de troca de cations determinada a pH 7,0, observou-se um aumento de, aproximadamente, 0,5 mEq/100 g para cada 0,1% de aumento do teor de carbono. Nos horizontes inferiores, com baixo teor de materia organica, pode-se estimar a CTC da caulinita como variando entre 1,5 e 3 mEq/100 g de argila. Nao se encontrou correlacao entre a diferenca da CTC medida a pH 8,2 e pH 7,0 com o teor de carbono organico. Os teores de fosfato adsorvido correlacionaram-se com as percentagens de oxi-hdroxidos de ferro e de aluminio. Para os horizontes A desses solos, a media de fosfato adsorvido foi de 1,24 mmole/100 g. ABSTRACT - The properties of cation exchange capacity and phosphate adsorption were studied In five solis under "cerrado" vegetation, collected in the Federal Territory of Amapá, Brazil. The cation exchange capacity at pH 7,0 was related to the organic matter content; the Increase of CTC was about 0,5 mEq per 0,1% carbon. In the Iower horizons, with 10w contents of organle matter, tha CTC of kaolinite could be estimated as varying from 1.5 to 3.0 mEq/100 g of clay. No correlation was found between the difference of CTC measured at p11 8.2 and 7.0 with the organic carbon content. The phosphate adsorbed was eorrelated with the percentage of oxihydroxides of iron and aluminurn. In the A horizons of the soils the average of phosphate adsorbed was 1.24 mmoles  aadsorption  aOxisols  aphosphorus  atropical soils  aAdsorção  aCerrado  aFosfato  aFósforo  aSolo  aAmapa  aAmazon  aAmazonas  aBrasil  aCTC  aLatossolos  aMacapa  aSolos tropicais1 aSANTOS, G. de A.1 aRAMOS, D. P.  tPesquisa Agropecáaria Brasileira, Brasíliagv.17, n.1, p. 27-32, jan. 1982.