Distribución de las fracciones de fósforo en suelos ácidos venezolanos
Changes in P soil fractions in Venezuela are not well known. The objectives of this study were to examine the distribution of P in acid soils, the fate of the soluble P applied to the soil and incubated for 140 days and P utilization by maize. Twelve acidic soils were used most with ten years of pho...
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2016
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| Online adgang: | http://hdl.handle.net/10872/14956 |
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| Summary: | Changes in P soil fractions in Venezuela are not well known. The objectives of this study were to examine the distribution of P in acid soils, the fate of the soluble P applied to the soil and incubated for 140 days and P utilization by maize. Twelve acidic soils were used most with ten years of phosphate fertilization, coming from Yaracuy, Portuguesa, Guárico, Barinas, Cojedes and Lara States. The soil samples were collected at a depth of 0-20 cm, are air dried and sieved with a 2 mm mesh. Soil fractions were determine by Tiessen and Moir (1993) sequential extraction. Two experiments were carried out, one of incubation and other in the greenhouse. For the incubation experiment, two treatments were used: phosphate fertilizer, 200 mg P.kg-1, in the form of triple superphosphate (1P) and without phosphate fertilizer (0P). Sampling was carried out at the 1, 35, 70 and 105 and 140 days of incubation. For the second experiment, once past the 140 days of incubation, soil were ground dried and 3.5 kg of soil potted and maize seeded, Plants were harvested 35 days after planting and the dry matter and the P in the tissue were determined. At harvest a sample of soil was taken to determine the fractionation of P and the available P by Olsen and Bray I Mehlich III methods. The results showed that PiR and PiL decreased when soil was incubated, but PiML increased, the recovery of PiML was about 50% in some soils. Distribution of applied P to the soils was related to P adsorption capacity of soils and to the Fe, Al and Ca content. Maize growth for 35 days produced a decrease of PiR, PiL, PiLL and PiML in the soils. Maize P uptake was close related to PiL and PiML fractions and maize root length decreased as PiL, PiLL and PiML increased. Olsen extractable P was the best estimate of available P for maize. |
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