Publication Date:
2019
Description:
Abstract
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 pHs (5.0 and 8.2) and temperatures (15, 25 and 35°C); the influence of polyphosphate addition on soil available micro‐nutrients (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 PO43‐ 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 with pH decreasing 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 favor the hydrolysis of short‐chain polyphosphate (aqueous incubation experiment), and polyphosphate significantly increases soil P availability and mobilizes soil micro‐nutrients. The application of polyphosphate can be recommended as a pragmatic P management strategy in agriculture, especially, soil temperature and pH should be taken into account when using polyphosphate fertilizers.
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Print ISSN:
0266-0032
Electronic ISSN:
1475-2743
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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