Some chemical and mineralogical properties of cocoa soils in Brazil
Soil samples were collected from the traditional cocoa producing zone of Southern Bahia as well as from areas potentially available for cocoa production both in Bahia State and in the Amazonian region. The pH of the soils ranged from 3.8 to 6.7. The pH's determined in water were in all cases higher than in KC1. The decrease in pH with depth agreed with the trend observed for KC1 extractable acidity. Most of the soils showed rather low values for base content but only in few cases was aluminum the dominant cation. The CEC by neutral NA OAc varied from 2.64 to 16.20 me/100 g and decreased with depth. Organic carbon showed the same trend. Considerable positive charge was present, especially in the B horizons, giving low effective net negative charge. In spite of the low negative charge measured at the field pH, a large pH dependent charge was present. X-ray analysis of the clay (Minor 2 micron) fraction revealed that differences in fertility among soils tested were mainly due to differences in clay mineralogy. The Amazonian soils apparently have less phosphate fixing capacity than the Southern Bahian soils, as indicated by their lower levels of iron oxides, and this can have practical significance relative to phosphate fertilizer practices
| Main Authors: | , |
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| Format: | biblioteca |
| Published: |
1976
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| Subjects: | SUELOS, PROPIEDADES FISICO-QUIMICAS SUELO, ZONAS CACAOTERAS, BRASIL, |
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