Reaction products of triammonium pyrophosphate in different Indian soils

Abstract

Studies were undertaken on the isolation and identification of reaction products of triammonium pyrophosphate (TPP), the major non-orthophosphate constituent of ammonium polyphosphate newly introduced in India, in representative soils of the alfisol, oxisol, entisol, mollisol and vertisol groups of India. Saturated solution of TPP were reacted with soils for periods of 30 minutes and one day with corresponding precipitation times of 15 days, three months and one year to isolate reaction products which were identified by X-ray diffraction technique, infra-red spectroscopy and chemical analyses. Six reaction products, namely, Ca(NH₄)₂P₂O₇ . H₂O, Mg(NH₄)₂P₂O₇ . 4H₂O, Ca(NH₄)₄H₂(P₂O₇)₂, Ca₃(NH₄)₄H₆(P₂O₇)₄.3H₂O, FeNH₄P₂O₇ and NH₄Al_0.33 Fe_0.67P₂O₇ were identified in different soils; Ca(NH₄)₂P₂O₇.H₂O and Mg(NH₄)₂P₂O₇ . 4H₂O occurring in abundance in most soils. Significant hydrolytic degradation of pyrophosphate reaction products to orthophosphate was not observed. Complementary studies where TPP in solid form was applied to soil, and reaction formed at and around the site of TPP placement were identified after six weeks incubation also showed the formation of Ca(NH₄)₂P₂O₇ . H₂O and Mg(NH₄)₂P₂O₇ . 4H₂O in the soils examined.