Premium
Availability of Phosphorus in the Water‐Insoluble Fraction of Monoammonium Phosphate Fertilizers
Author(s) -
Bartos J. M.,
Mullins G. L.,
Sikora F. J.,
Copeland J. P.
Publication year - 1991
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1991.03615995005500020042x
Subject(s) - chemistry , phosphorus , phosphate , fertilizer , sorghum , phosphorite , reagent , phosphate fertilizer , forage , ammonium phosphate , agronomy , fraction (chemistry) , monocalcium phosphate , environmental chemistry , chromatography , biochemistry , fish <actinopterygii> , fish meal , organic chemistry , fishery , biology
Declining reserves of premium‐grade phosphate rock (PR) have resulted in a reliance on lower grade ore to met the needs for phosphate fertilizer production. Elemental impurities, primarily Fe, Al, Mg, and K, are released from closely associated accessory minerals during acidulation of PR. These impurities result in the formation of sludge compounds in the wet‐process acid, and in impurity compounds in commercial monoammonium phosphate (MAP, NH 4 H 2 PO 4 ) fertilizers. Plus, these impurity compounds are generally water insoluble, thus reducing the level of water‐soluble P in commercial MAP fertilizers. A greenhouse study was initiated to determine the availability of P in the water‐insoluble fractions of MAP fertilizers. Seven commercial MAP fertilizers were selected to represent the major U.S. sources of PR (Florida, North Carolina, and Idaho). The water‐soluble P was removed by washing with deionized water, and the remaining material having low water‐soluble P was compared with reagent‐grade MAP (100% water soluble). The water‐insoluble‐P‐containing materials produced lower sorghum‐sudangrass ( Sorghum bicolor [L.] Moench) yield and less P uptake than water soluble reagent‐grade MAP. Forage yields and P uptake were dependent on the source of the water‐insoluble fraction. Phosphorus soluble in neutral ammonium citrate was not a reliable measure of short‐term P availability in the water‐washed fertilizer fractions.