『Abstract
　The phosphorus (P) resources worldwide are limited, and the prices of commercial P fertilizer continue to increase. Therefore, the use of P containing wastes is important for P recycling in agriculture. The P fractionation methods have been widely applied to characterize the effect of land use practice on soil P dynamics. Information about effect of organic manures on available P and inorganic P (Pi) fractions in calcareous soils of Chaharmahal va Bakhtiari province is limited. The objectives of this research were to study the effect of municipal compost (MC) on available P and Pi forms in five calcareous soils. Municipal compost was applied at the rates of 0, 0.5, 1.0, 1.5 and 2.9 ％ (w/w). samples were incubated at 25±1℃ and 20％ moisture content for 150 days. At the end of incubation, available P in MC-treated soils was extracted by Olsen, AB-DTPA and 0.01 M CaCl2 methods. Also, phosphorus was fractionated chemically into labile P (LP), non-occluded P (NP), re-adsorbed P (RP), occluded P (OP), calcium phosphates (CaP) and residual P. The results showed that there was a linear increase in soil available P with MC application. There was a significant positive relationship between Olsen-P, AB-DTPA-P and 0.01 M CaCl2-P, and MC additions with slopes ranged from 0.471 to 0.583, 0.032 to 0.106, and 0.033 to 0.081, respectively. The increase in soil test P (STP) from MC addition was not related to the initial STP of the soils. A sharp increase in LP, NP and CaP and decrease in residual P concentration occurred in all soils with MC application. It can be concluded that MC applied to calcareous soils may enhance P nutrition of plants. Furthermore, applied P partitioning into the relatively available forms means the potential erosion losses of P to streams and other bodies of water.

Keywords: Municipal compost; Phosphorus; Fractionation; Calcareous soils』

Introduction
Materials and methods
Results and discussion
Conclusion
References