Early-stage changes in chemical phosphorus speciation induced by liming deforested soils
Abstract A hypothesis of whether an increase in Ca2+ due to liming acid soils causes an increase in Ca-phosphates with a concomitant decrease in Al- and Fe-phosphates was tested on a relatively short-term time frame, as observed in the investigations of chemical phosphorus (P) speciation. Soil samples were taken at a deforested site and split into three treatment groups: a control and two CaCO3 treatments (0.1 and 0.4 g CaCO3 in 100 g soil). Each soil was incubated at 25±2°C for 40 days. Inorganic-P was partitioned into three fractions: Fraction-A (Al- and occluded Fe-P), Fraction-B (non-occluded Fe- and adsorbed-P), and Fraction-C (Ca-P). The pH of CaCO3-treated soils decreased right after liming, indicating a probable formation of solid phosphate compounds. Available P in CaCO3-treated soils decreased from 0.67 mg kg-1 to control levels at the end of incubation. Total-P and organic-P of CaCO3-treated soils were virtually the same as those of control soils, while inorganic-P varied. Fraction-A in both CaCO3-treated soils peaked at 10 days of incubation, and then decreased below control levels, while Fraction-B decreased abruptly right after liming, and thereafter gradually decreased. Liming decreased Fraction-C, and caused an increase in Al- and Fe-P due to an increase in exchangeable Al3+ and Fe3+. Our results challenge the hypothesis by showing the unexpected opposite data for Al-, Fe- and Ca-P compounds at least in the early stage of equilibrium disturbances due to liming an acidic soil.
| Main Authors: | , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Chilean Society of Soil Science / Sociedad Chilena de la Ciencia del Suelo
2018
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| Online Access: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-95162018000200435 |
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