Variation of soil organic phosphorus fractions, and relationship of organic P and its fractions, with soil organic matter
and readily
available P were studied with Bowman-Cole method. The results showed that active Po,
moderately active Po, moderately stable Po and highly stable Po accounted for 80.2%, 9.8%, 9.0 % and 2.0 % of total Po, respectively. And combined application of organic manure and inorganic fertilizer significantly increase contents of active Po, moderately active Po and moderately stable Po, but decreased highly stable Po. Application of chemical fertilizer increased total amount and activity of Po. and content of moderately active Po, but decreased contents of highly and moderately stable Po, and had no significant influence on distribution of Pofractions. Activity and moderately active Po showed positive relationship with readily available P, organic matter and total organic P, whereas moderately and highly stable Po had nothing to do with readily available P and organic matter.