Standardization of phosphate rocks

Sinclair A.G., . and Rajan S.S.S., . and Watkinson J.H., . (1992) Standardization of phosphate rocks. [Proceedings Paper]

The effectiveness of phosphate rocksPR as direct application phosphate fertilizers depends on the properties of soil and plants for which they are used as well as the intrinsic properties of the PR themselves. Standardization of PR is taken to mean their characterization in terms which assist the prediction of their performance as phosphate fertilizers in specified agricultural situations. Laboratory tests of PR reactivity i.e. ability to release P generally consist of measuring the amount of P dissolved in one of several organic acid or salt solutions under strictly specified conditions. Solubility tests with citric and formic acids and with neutral ammonium citrate generally give similar reactivity rankings among PR and correlate fairly well with agronomic performance of PR in glasshouse and field trials. The influence of particle size on PR reactivity can be incorporated into solubility tests by conducting these on PR in the same state of fineness as applied to the soil. These empirical solubility tests contribute little to understanding and modelling the PR dissolution process and a more fundamental assessment of PR reactivity can be based on solubility product and by recent improvements in analytical techniques for measuring PR residues and should increasingly be used in basic studies of PR performance. An index of the ability of soils to dissolve PR is urgently required. In combination with an index of PR reactivity this should provide a system for predicting the agronomic performance of any PR in any agricultural environment. This paper discusses a current approach to this objective

Full text available from:

Abstract

The effectiveness of phosphate rocksPR as direct application phosphate fertilizers depends on the properties of soil and plants for which they are used as well as the intrinsic properties of the PR themselves. Standardization of PR is taken to mean their characterization in terms which assist the prediction of their performance as phosphate fertilizers in specified agricultural situations. Laboratory tests of PR reactivity i.e. ability to release P generally consist of measuring the amount of P dissolved in one of several organic acid or salt solutions under strictly specified conditions. Solubility tests with citric and formic acids and with neutral ammonium citrate generally give similar reactivity rankings among PR and correlate fairly well with agronomic performance of PR in glasshouse and field trials. The influence of particle size on PR reactivity can be incorporated into solubility tests by conducting these on PR in the same state of fineness as applied to the soil. These empirical solubility tests contribute little to understanding and modelling the PR dissolution process and a more fundamental assessment of PR reactivity can be based on solubility product and by recent improvements in analytical techniques for measuring PR residues and should increasingly be used in basic studies of PR performance. An index of the ability of soils to dissolve PR is urgently required. In combination with an index of PR reactivity this should provide a system for predicting the agronomic performance of any PR in any agricultural environment. This paper discusses a current approach to this objective

[error in script]

Item Type:	Proceedings Paper
Additional Information:	2 fig. 4 tables; 29 refs. Summary En
AGROVOC Term:	FOSFATO MINERAL
AGROVOC Term:	NORMAS
AGROVOC Term:	FOSFORO
AGROVOC Term:	SOLUBILIDAD
AGROVOC Term:	DISOLUCION
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:26
URI:	http://webagris.upm.edu.my/id/eprint/15042

Actions (login required)

View Item