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The effect of land use on the availability of soil nitrogen (N) was studied by separating total soil N into one labile and one stable fraction by oxidation and extraction of labile N with potassium permanganate. The nitrogen management index (NMI) was calculated according to Blair et al. (1995) f...


Westerhof, RVilela, LAyarza, Miguel AngelZech, W.[Labile N and the nitrogen management index of oxisols in the Brazilian cerrados]Labile N and the nitrogen management index of oxisols in the Brazilian cerrados

In the Cerrados, a large savanna region in Brazil, the effects of different land use on aggregation in Oxisols were studied, using laser diffraction grain-size analyses. The topsoil of plowed systems had significantly fewer macroaggregates (194-2000 micro m) and a significantly larger fraction of...


Westerhof, RBuurman, PGriethuysen, C. vanAyarza, Miguel AngelVilela, LZech, W.[Aggregation studied by laser diffraction in relation to plowing, soil organic matter, and lime in the Brazilian cerrados]Aggregation studied by laser diffraction in relation to plowing, soil organic matter, and lime in the Brazilian cerrados

The permanganate oxidation procedure is easily performed and may help monitor large areas for their soil organic matter (SOM) quality and nitrogen (N) availability. Knowledge of the chemical characteristics of fractions that are lost or remain after oxidation will help explain results obtained by...


Westerhof, RVilela, LAyarza, Miguel AngelZech, W.[Characterization labile and stable nitrogen]Characterization labile and stable nitrogen

Short-term changes in soil aggregation, total and particulate organic C and N were studied in cropping and pasture systems of the Brazilian savannas, also known as the Cerrados. Furthermore, the concepts of a hierarchical aggregate structure and of the interaction of soil structure with particula...


Freibauer, A.Westerhof, RAyarza, Miguel AngelSilva, J.E. daZech, W.[Short-term variation in aggregation and particulate organic matter under crops and pastures]Short-term variation in aggregation and particulate organic matter under crops and pastures

Soil 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 importan...


Westerhof, RVilela, LAyarza, Miguel AngelZech, W.[Carbon fractions as sensitive indicators of quality of soil organic matter]Carbon fractions as sensitive indicators of quality of soil organic matter

We examined whole-soil samples and particle-size fractions to study the distribution of different phosphorus (P) fractions after land-use change from native savanna to crops, pasture, and reforestation on clayey and loamy Oxisols of the Brazilian savannas. Phosphorus was extracted sequentially, a...


Westerhof, RSilva, J.E. daAyarza, Miguel AngelZech, W.[Phosphorus fractions under different land-use systems in oxisols of the Brazilian cerrados]Phosphorus fractions under different land-use systems in oxisols of the Brazilian cerrados

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