Disponibilidad de fósforo en suelos de cacao de Bahía
Samples from eight soil profiles from the Bahian cacao region were analysed for their inorganic forms of phosphorus and their total phosphorus content. Other samples taken from near the soil surface were analysed for their phosphorus content by various chemical methods, some samples being incubated with lime, others not. The results from the different extraction methods were compared with the growth of sorghum (Sorgum vulgare) and cacao seedlings (Theobroma cacao L.). The degree of phosphorus fixation of these soils was also determined. Two of the eight profiles had a total phosphorus content greater than 1.700 ppm, while the remainder had between 150 and 550 ppm, the organic fraction usually making up 55 percent of the total. The inorganic phosphorus forms, most of which were in the inactive form, were found in the following proportions: reductant soluble-P (39.5 per cent); Fe-P (24.8 per cent); occluded-P (24 percent); Ca-P (9.5 percent)ç Al-P (2.0 percent). In the first comparison experiment between the different extraction methods, the Truog and the Olsen methods correlated more closely with the growth of the sorghum than either the Egner-Riehm or the North Carolina (ratio of soil to extractor solution 1:4 and 1:10) methods. There was no influence due to the liming but the extraction capacity varied according to the method used. The comparison of the different extraction methods and the dry matter of the cacao seedling gave correlation coefficients in the following declining order: Truog major Egner-Riehm major Olsen modified major Olsen major North Carolina. The different levels of response to the phosphorus were also determined for the various extraction methods. The fixation of phosphorus of the Bahian cacao soils compared with that of other tropical soils is discussed with special reference to the influence of liming and the free oxides of aluminium and iron
| Main Authors: | , , , , , , , , , , |
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| Format: | biblioteca |
| Published: |
St. Augustine (Trinidad y Tobago)
1972
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| Subjects: | SUELOS DE CACAO, FOSFORO, DISPONIBILIDAD DE NUTRIENTES, FRACCIONAMIENTO, FOSFATOS, ANALISIS QUIMICO, PERFIL DEL SUELO, ENCALADO, BAHIA, BRASIL, |
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| Summary: | Samples from eight soil profiles from the Bahian cacao region were analysed for their inorganic forms of phosphorus and their total phosphorus content. Other samples taken from near the soil surface were analysed for their phosphorus content by various chemical methods, some samples being incubated with lime, others not. The results from the different extraction methods were compared with the growth of sorghum (Sorgum vulgare) and cacao seedlings (Theobroma cacao L.). The degree of phosphorus fixation of these soils was also determined. Two of the eight profiles had a total phosphorus content greater than 1.700 ppm, while the remainder had between 150 and 550 ppm, the organic fraction usually making up 55 percent of the total. The inorganic phosphorus forms, most of which were in the inactive form, were found in the following proportions: reductant soluble-P (39.5 per cent); Fe-P (24.8 per cent); occluded-P (24 percent); Ca-P (9.5 percent)ç Al-P (2.0 percent). In the first comparison experiment between the different extraction methods, the Truog and the Olsen methods correlated more closely with the growth of the sorghum than either the Egner-Riehm or the North Carolina (ratio of soil to extractor solution 1:4 and 1:10) methods. There was no influence due to the liming but the extraction capacity varied according to the method used. The comparison of the different extraction methods and the dry matter of the cacao seedling gave correlation coefficients in the following declining order: Truog major Egner-Riehm major Olsen modified major Olsen major North Carolina. The different levels of response to the phosphorus were also determined for the various extraction methods. The fixation of phosphorus of the Bahian cacao soils compared with that of other tropical soils is discussed with special reference to the influence of liming and the free oxides of aluminium and iron |
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