AbstractBackgroundPhosphorus (P) fertilizer properties and nutrient management strategies substantially affect soil P availability as well as uptake and consequently crop yield.AimsThe present study aims to study the potential use of inorganic soluble polyphosphates (Poly‐P) as slow‐release fertilizer under drip fertigation.MethodsA pot experiment was conducted using an alkaline soil. Two Poly‐P fertilizers, differing in their polymerization rate (Poly‐53 with 53% and Poly‐100 with 100% Poly‐P of the total‐P content), were compared to an orthophosphate (Ortho‐P) and a treatment without P application (control) under three drip fertigation frequencies (Fsow: P fertilizer applied at sowing, Fweek: once a week, and F3days: every 3 days). Soil samples were taken at 40 days after sowing and at harvest from 3 layers (0–5, 5–10, and 10–20 cm) to determine P availability in soil (Olsen‐P) and its relocation into deeper soil layers. Furthermore, plant growth, yield, P uptake, P use efficiency, as well as water productivity were investigated.ResultsSoil P availability varied significantly between fertilizer forms and fertigation frequencies. At higher polymerization rate of the Poly‐P fertilizer, P becomes less mobile in the soil, but its availability is maintained until harvest. The analysis of Olsen‐P at harvest showed that the higher P availability in soil was obtained with Poly‐P forms with higher values in the 0–5 and 5–10 cm soil layers than in the 10–20 cm. In addition, weekly fertigation (Fweek) revealed the best results in terms of P availability compared to other P fertigation regimes, and all P fertilizers significantly improved chickpea grain yield, seed quality, and water productivity, compared to the unfertilized control.ConclusionPoly‐P fertilizers can be recommended as an effective source of phosphorus for plants, due to their slow‐release properties. Using Poly‐P, the frequency of P application through the drip fertigation system can be reduced while ensuring high crop yields.