Abstract: A laboratory experiment was conducted to study the effect of incubation period on the phosphorus adsorption by the Pindorian, Satghrah, Shandara, Wazirabad, Balkassar, Hafizabad and Missa soil series of Pakistan. Five levels of P (50, 100, 200, 400 and 800 μg P/g of soil) were added to these samples and incubated for 1, 7 and 15 days. Results showed that the amount of adsorbed P increased by increasing the incubation period from 1 to 15 days. The highest adsorption was found after 15 days incubation period and lowest P was adsorbed after incubation period of one day in all the soils and each level of P application.