- 1Agricultural Research Organization- Volcani Institute, Soil and Water, Gilat, Israel (ranerel@volcani.agri.gov.il)
- 2The Robert H.S faculty of agriculture, food and environment, The Hebrew university of Jerusalem
- 3Ben-Gurion University of the Negev, The Jacob Blaustein Institutes for desert research
Low phosphorus (P) fertilizer utilization efficiency remains a major constraint in calcareous and semi-arid soils due to rapid sorption and precipitation of orthophosphate (orthoP). Polyphosphate (polyP) fertilizers have been proposed as an alternative P source, yet their interactions with rhizosphere microorganisms and the implications for plant P acquisition are still insufficiently understood.
Here, we investigated how P fertilizer type (orthoP vs. polyP) influence rhizosphere microbial activity, enzymatic processes, and plant P uptake. Field and pot experiments were conducted under low initial soil P conditions (Olsen P ≈ 8 mg kg⁻¹), combining crop performance measurements with analyses of arbuscular mycorrhizal fungi (AMF), phosphate-solubilizing and polyphosphate-hydrolyzing bacteria, and rhizosphere phosphatase activity.
PolyP fertilization consistently altered rhizosphere biological activity compared with orthoP. PolyP treatments increased the abundance and activity of phosphate-solubilizing and polyphosphate-hydrolyzing bacteria, which were able to utilize polyP as a sole P source. PolyP hydrolysis by bacteria was not directly associated with bulk pH changes, indicating enzymatic rather than purely chemical control. In parallel, polyP enhanced AMF colonization in both field-grown wheat and pot-grown tomato, suggesting improved biological P acquisition pathways. Acid and alkaline phosphatase activities in the rhizosphere were generally higher under polyP fertilization, reflecting enhanced microbial and plant-driven P mobilization.
These results demonstrate that P fertilizer type strongly regulates rhizosphere microbial communities and enzymatic activity, with polyP promoting biologically mediated P transformation and uptake. Our findings highlight the importance of considering soil–plant–microbe interactions when evaluating alternative P fertilizers and developing strategies to improve P use efficiency in calcareous soils.
How to cite: Erel, R., Shabtai, D., Kushmaro Biera, A., Nahari, I., Mutakale, I., and Toren, N.: Effects of phosphorus fertilizer type on rhizosphere microbial activity and plant phosphorus acquisition, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21453, https://doi.org/10.5194/egusphere-egu26-21453, 2026.
