Phosphorus Availability to Corn as Affected by Granulating Manganese with Ortho- and Pyrophosphate Fertilizers
1969
Giordano, P. M. | Mortvedt, J. J. (John J.)
The presence of MnSO₄ at a level of 10% Mn in granular ammonium polyphosphate (APP) and triammonium pyrophosphate (TPP) significantly reduced corn (Zea mays L.) forage yields and P uptake relative to treatments where P and Mn were applied separately in greenhouse pots. A significant reduction in P uptake resulted when MnSO₄ was combined with monoammonium phosphate (MAP), but no yield reduction occurred. Chemical extraction of the fertilizers indicated that the solubilities of both P and Mn were reduced when MnSO₄ was granulated with APP or TPP. A compound of very low solubility, Mn(NH₄)₂P₂O₇ · 2H₂O, was identified as the principal reaction product. Accordingly, movement of P in soil was restricted to a greater extent when MnSO₄ was combined with TPP than with MAP.
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