Calcium Phosphate Fertilizers: II. A Petrographic Study of Their Alteration in Soils1
- J. R. Lehr and
- W. E. Brown2
As a supplemental study to pot-culture tests in which six calcium phosphates were investigated, petrographic examinations were made of the fertilizer residues and surrounding soils. The materials tested were Ca(H2PO4)2 · H2O, CaHPO4 · 2H2O, CaHPO4, Ca4H(PO4)3 · 3H2O, Ca3(PO4)2, and Ca10(PO4)6(OH)2).
The purpose was to determine the physical and chemical alterations that the materials had undergone while in a soil environment and in the presence of feeding roots. Correlations between these observations and plant response were sought.
Some correlation was found between plant response and; (a) relative rates of solution or solubilities of the phosphates, and (b) chemical alterations of the phosphates. Positive evidence was found for 4 hydrolysis reactions, 2 of which confirm the postulated formation of octocalcium phosphate and apatite. Other observations lend new support to the concept of contact feeding by plant roots.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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