02027naa a2200349 a 450000100080000000500110000800800410001910000180006024500800007826000090015830000150016752010070018265000110118965000150120065000190121565000130123465000190124765000270126665000090129365000120130265000120131465000230132665000200134965000160136965000110138565000300139665000090142670000150143570000180145070000130146877301960148115454031999-07-15       1999    bl uuuu     u00u1 u    #d1 aWESTERHOF, R.  aCarbon fractions as sensitive indicators of quality of soil organic matter.  c1999  ap.123-132.  aSoil organic matter quality is usually seen as a major attribute of soil quality. In this study, we extracted organic carbon with water (WEOC) or with potassium permanganate (PEOC). We assessed these extractions for their potential as sensitive indicators of the effect of land use on two important soil functions: biological activity and nutrient availability. Water-extractable organic carbon and PEOC were better correlated with C and N mineralization in the laboratory than were total and stable C, and were mineralization flush that occurs at the beginning of the wet season. However, the more stable fraction also seemed to contribute to the pool of mineralizable C and N was, within 5 years, siginificantly effected by changes in land use. Extraction of labile soil organic carbon with water and permanganate is an easy and valuable screening method for comparing the short-term effects of land-use systems on biological activity and nutrient availability in the soils of the Brazilian savannas.  acarbon  aFerralsols  amineralization  anitrogen  aorganic matter  apotassium permanganate  asoil  aCarbono  aCerrado  aMatéria Orgânica  aMineralização  aNitrogênio  aOxisol  aPermanganato de Potássio  aSolo1 aVILELA, L.1 aAYARZA, M. A.1 aZECH, W.  tIn: THOMAS, R.; AYARZA, M.A., ed. Sustainable land management for the oxisols of the Latin American savannas: dynamics of soil organic matter and indicators of soil quality. Cali: CIAT, 1999.