Phosphorus release from apatite mineral using some organic amendments and their effect on some clay loam soil properties

A pot incubation experiment was conducted to assess the impact of some organic amendments (citric acid, compost and Bacillus megaterium) on phosphorus releasing from two apatite levels (2 and 4 g/pot) added to clay loam soil as well as investigating its effect on some soil chemical properties at four incubation periods of total 12 months. The obtained results indicated that the soil electrical conductivity varied from 1.115 to 1.555 dS/m with the application of apatite levels 1 and 2, respectively. However, the highest reduction in the soil pH from 8.05 to 7.57 was found via the citric acid addition compared to the control. Furthermore, it is found that the integrated application of apatite level 2 with compost had the highest capability to increase phosphorus availability while the B. megaterium came second. So, the periods mean of level 2 was higher than of level 1 as well as the mean of treatments. Also, the 2nd period of the soil incubation showed the highest phosphorus (P) variation. It could be summarized that the apatite+compost followed by the apatite+phosphorus solubilizing bacteria (PSB) had the highest contribution in the P availability.