Effect of fertilizer sources on chemical and organic forms of phosphorus under wheat cultivation in a calcareous soil

The distribution of phosphorus (P) forms is very important to evaluate the soil P in calcareous soils. Organic fertilizers increase the soil P dynamics by adding organic matter. This experiment was conducted by using 50 mg P kg-1 soil from sheep manure (SM), municipal solid waste compost (MSWC) and triple superphosphate (TSP) treatments with control (without fertilizer) in a calcareous soil in greenhouse conditions. At the end of the plant's physiological growth, dry weight of shoots, phosphorus concentrations of wheat, organic and inorganic forms of soil P were measured. The results showed that by using of 50 mg P kg-1 soilfrom SM, the highest P uptake by wheat was obtained from TSP treatment. All organic P forms significantly increased (P<0.05) in comparison with the control, but Highly Resistant Organic Phosphorus (HROP) showed invers trend. Moderately Resistant Organic Phosphorus (MROP) had the highest of organic P fraction and the Labile Organic Phosphorus (LOP) was the least. The highest fraction of mineral phosphorus was the apatite form. By applying of 50 mg P kg-1 soil from SM and TSP, Ca2P form increased by 4.2 and 3.9 times compared to control respectively. The AlP form increased by applying SM. MSWC and TSP treatments at 31.0, 44.0 and 46% compared to control, respectively. According to the research data, with the application of 50 mg P kg-1 soil from the source SM, increased organic phosphorus forms and by 50 mg P kg-1 soil from the source TSP, increased phosphorus absorption and its mineral forms in wheat cultivation.