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Comparison of the hydrolysis characteristics of three polyphosphates and their effects on soil phosphorus and micronutrient availability
Author(s) -
Wang Xuewei,
Gao Yanju,
Hu Baowei,
Chu Guixin
Publication year - 2019
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/sum.12526
Subject(s) - polyphosphate , chemistry , hydrolysis , ammonium polyphosphate , phosphorus , phosphate , calcareous , micronutrient , zinc , environmental chemistry , agronomy , biochemistry , botany , organic chemistry , raw material , biology
Polyphosphate is an alternative phosphorus (P) source which can substitute for orthophosphate‐based P fertilizers in agriculture. In order to explore the effects of polyphosphate addition on soil P availability, and how pH and temperature affect polyphosphate hydrolysis, an aqueous and a soil incubation experiment were conducted at different pH s (5.0 and 8.2) and temperatures (15, 25 and 35°C); the influence of polyphosphate addition on soil available micronutrients (i.e., iron—Fe, manganese—Mn and zinc—Zn) was also studied. The experiments used three different polyphosphate fertilizers (solid and liquid ammonium polyphosphate and polyphosphoric acid) and two soil types (acid and alkaline). In aqueous incubation conditions, the average amount of phosphate ( PO 4 3 − ) released from polyphosphate fertilizers at 35°C was 2.7 times greater than at 25°C. The average Olsen P in polyphosphate‐treated soil at 35°C was 1.12 times greater than at 25°C, indicating that higher temperature facilitates polyphosphate hydrolysis. Polyphosphate hydrolysis increased as the pH decreased in aqueous solution, but its hydrolysis rate was greater in calcareous soil than in acid soil. Moreover, polyphosphate significantly increased soil available Fe, Mn and Zn concentrations by an average of 14%, 16% and 20%, respectively, relative to orthophosphate fertilizer. In summary, high temperature and low pH favour the hydrolysis of short‐chain polyphosphate (aqueous incubation experiment), and polyphosphate significantly increases soil P availability and mobilizes soil micronutrients. The application of polyphosphate can be recommended as a pragmatic P management strategy in agriculture: however, soil temperature and pH should be taken into account when using polyphosphate fertilizers.