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Orthophosphate solubility in waters of different ionic composition
Year:
1995
Authors :
Bar-Yosef, Bnayahu
;
.
Keinan, Miriam
;
.
Levkovitch, Irit
;
.
Volume :
44
Co-Authors:
Imas, P., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Bar-Yosef, B., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Levkovitch, I., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Keinan, M., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Facilitators :
From page:
73
To page:
78
(
Total pages:
6
)
Abstract:
Orthophosphate (OP) is a major component of irrigation and nutrient solutions. Since OP precipitates may clog drippers, and deviations from intended OP concentrations may adversely affect plant development and yield, an understanding of the mechanisms controlling OP solubility in solutions of various ionic compositions, is essential. The objectives of this study were (i) to suggest guidelines for permitted OP additions to waters of various ionic compositions, so as to avoid OP crystallization and (ii) to predict the decrease in OP concentration as a function of time in supersaturated solutions. Five freshwater sources, used for irrigation in Israel, and representing extremes of pH and of Ca, HCO3 and SO4 concentrations, were tested. Solutions of three different initial OP concentrations (10, 30 and 90 mg Pl-1) and two pH values were prepared in 21 plastic bottles and kept in a dark room at 27 °C. Solution samples were withdrawn from the bottles at predetermined times, filtered and analysed for pH and total OP, Ca and HCO3 concentrations. In all the studied waters and for all initial OP levels the OP concentration (Cp) declined with time. The rate of decrease in Cp was proportional to the difference between the observed and equilibrium Cp values, with a specific rate constant for each water.The pH and the Ca2+ and HCO3- activities in solution were influenced by the initial Cp. The equilibrium Cp in all treatments was found to be controlled by octacalcium phosphate (OCP). Available chemical equilibria models allow to calculate the maximum level of OP that can be added to various waters before OCP precipitates, based on water pH and Ca, HCO3 and SO42- concentrations. © 1996 Kluwer Academic Publishers.
Note:
Related Files :
Agriculture
ionic composition
octacalcium phosphate
orthophosphate
pH
P precipitation
solid phase
Solubility
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Related Content
More details
DOI :
10.1007/BF00750694
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
19259
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:27
Scientific Publication
Orthophosphate solubility in waters of different ionic composition
44
Imas, P., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Bar-Yosef, B., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Levkovitch, I., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Keinan, M., Institute of Soils and Water, Agricultural Research Organization, Bet Dagan, 50250, Israel
Orthophosphate solubility in waters of different ionic composition
Orthophosphate (OP) is a major component of irrigation and nutrient solutions. Since OP precipitates may clog drippers, and deviations from intended OP concentrations may adversely affect plant development and yield, an understanding of the mechanisms controlling OP solubility in solutions of various ionic compositions, is essential. The objectives of this study were (i) to suggest guidelines for permitted OP additions to waters of various ionic compositions, so as to avoid OP crystallization and (ii) to predict the decrease in OP concentration as a function of time in supersaturated solutions. Five freshwater sources, used for irrigation in Israel, and representing extremes of pH and of Ca, HCO3 and SO4 concentrations, were tested. Solutions of three different initial OP concentrations (10, 30 and 90 mg Pl-1) and two pH values were prepared in 21 plastic bottles and kept in a dark room at 27 °C. Solution samples were withdrawn from the bottles at predetermined times, filtered and analysed for pH and total OP, Ca and HCO3 concentrations. In all the studied waters and for all initial OP levels the OP concentration (Cp) declined with time. The rate of decrease in Cp was proportional to the difference between the observed and equilibrium Cp values, with a specific rate constant for each water.The pH and the Ca2+ and HCO3- activities in solution were influenced by the initial Cp. The equilibrium Cp in all treatments was found to be controlled by octacalcium phosphate (OCP). Available chemical equilibria models allow to calculate the maximum level of OP that can be added to various waters before OCP precipitates, based on water pH and Ca, HCO3 and SO42- concentrations. © 1996 Kluwer Academic Publishers.
Scientific Publication
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