Using of phosphorus fertilizers in agriculture production affects on environmental quality, to minimize chances of negative environmental impact from over fertilization we should place them in correct form and with suitable application way. Water solubility and acidity of phosphate fertilizers used in fertigation are critical parameters in choosing the phosphate fertilizers. A column experiment was conducted out to study the effect of phosphorus fertilizers forms (mono-ammonium phosphate (MAP),

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... mono-potassium phosphate (MKP), urea phosphate (UP) and phosphoric acid (PA), fertigation frequencies (every 3 and 6 days) and amount of irrigation water (0.66 and 1.32 L day ) on the movement and availability of P in sandy calcareous soils. Increasing the 1 amount of irrigation water revealed a highly significant effect (p<0.01) on the distribution of available P underneath the dripper through the soil column. Urea-phosphate and phosphoric acid (acidic P fertilizers) were more mobile compared to the other P fertilizers. Continuous injection of P fertilizer with irrigation water (high-frequency P drip fertigation, P injection every 3 days) significantly (p<0.01) increased the Olsen's extractable P in the surface layers. Based on our results, it may be concluded that amount of water irrigation and fertigation frequency are major factors influenced P availability and movement in sandy calcareous soils. Phosphorus fertilizers in sandy calcareous soils must be added in high frequency with low concentrations.