The effect of the incubation period on the availability of phosphorus in calcareous soils of different agricultural exploitation in Nineveh Governorate

Abstract

An incubation experiment was conducted on six calcareous soils of different textures and agricultural uses to find out the effect of time on phosphorus added to the soil through nanofertilizer. 5 levels of NPK nano fertilizer were added to each soil (120, 80, 40, 20,0) mg kg-1. The experiment lasted for 6 months, where soil samples were taken at each of the different incubation periods (1, 7, 15, 30, 45, 60). After that, the samples were dried and the ready phosphorus was measured to calculate the fixed phosphorus from the difference between the added phosphorus and the ready phosphorus. The results showed that the highest level of available phosphorus in all soils was during the first incubation period, which was one day. Then the rate of available phosphorus decreased with time, reaching its lowest value at the last period of incubation, which is 60 days. The results also showed the superiority of uncultivated forest soil in the rate of available phosphorus remaining after the end of incubation, followed by cultivated forest soil, uncultivated Shalalat soil, cultivated shalalat soil, uncultivated Qubbah soil, and finally the cultivated Qubbah soil, which recorded the lowest rate of ready phosphorus after the end of the incubation periods.