AU - A. Halajnia, AU - G. H. Haghnia, AU - A. Fotovat, AU - R. Khorasani, TI - Effect of Organic Matter on Phosphorus Availability in Calcareous Soils PT - JOURNAL ARTICLE TA - JSTNAR JN - JSTNAR VO - 10 VI - 4 IP - 4 4099 - http://jstnar.iut.ac.ir/article-1-610-en.html 4100 - http://jstnar.iut.ac.ir/article-1-610-en.pdf SO - JSTNAR 4 ABĀ  - Study of phosphorus reactions over time and the role of organic matter in the calcareous soils are important for the development of P fertilizer and manure management practices. The objective of this study was to determine the effect of applied manure on P availability and its chemical forms in the soil, over time. Eight samples were collected from semi-arid calcareous soils of Mashhad plain. The samples were treated with two levels of inorganic P (0 and 300 mg P kg-1 soil as KH2PO4) and two levels of organic matter (0 and 1% cattle manure). The experiment was conducted in a completely randomized design with factorial arrangement. The treated soil samples were incubated for 2, 5, 10, 30, 60, 90 and 150 days, then analyzed for available P (Olsen-P). The result showed that only 17% of added phosphorus was available in P treatment at the end of experiment. In manure treated soils, this figure reached 34% for the same period of time. Application of manure along with P increased the recovery of applied P and CBD-P (Citrate-Bicarbonate-Dithionite). This may be due to the formation of P-organic complexes with Fe oxides. Application of manure in soil increased NaCl-NaOH-P considerably compared with P and P+OM treatments. It can be concluded that P originating from manure compared with inorganic-P may be more available for plants over the time. CP - IRAN IN - LG - eng PB - JSTNAR PG - 121 PT - Research YR - 2007