Afericao de níveis de potássio em solos da regiao sul da Bahia
Available potassium was measured for 11 soils from Southern Bahia. Five extraction methods were used: Mehlich, Truog, 0. 1N H2SO4, 1N HNO3, 1N NH4OAc at pH 7.0. Pot experiments were made in the greenhouse to test the response of cocoa seedlings (Theobroma cacao L.) to rising levels of potassium added to the soils. The experiment was completely randomized with four replications. Potassium was added at rates equivalent to 0, 30, 60, 90 and 120 kg (K2O per hectare), with a basic fertilizer of nitrogen, phosphorus, calcium, magnesium and micronutrients being applied to all treatments. The cocoa seedlings were harvested after 150 days and the dry weights obtained of the leaves and stems and the roots. The order of the extraction capacity for the different methods was 1N HNO3 major Truog major 0.1N H2SO4 major 1N NH4OAc - pH 7.0 major Mehlich. The average correlation between the dry weights of the leaves and stems and the roots compared with the five different extraction methods based on the zero K treatment was 54 per cent for the leaves and stems and 47 per cent for the roots. The best correlation was found for the methd 0.1N H2SO4 and the lowest for the 1N HNO3. Application of potassium to the soils with a potassium content greater than 0.12 mEq/100g has no significant effect on cocoa seedling growth, although highly significant results were found for three soils to which potassium had been added. Critical levels of potassium for the Mehlich and Truog extractants were set at 0.12 mEq/100g and 0.13 mEq/100g for the 0.1N H2SO4 and the 1N NH4OAc pH 7.0
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| Format: | biblioteca |
| Published: |
1973
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| Subjects: | SUELOS, VALOR NUTRITIVO, FOSFORO, DISPONIBILIDAD DE NUTRIENTES, FERTILIDAD DEL SUELO, BAHIA, BRASIL, |
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