Differentiation Regularity Of Organic Phosphorus Components In Soil Profile Of Apple-pear Orchard In Yanbian Region

In order to research soil phosphorus cycle at apple-pear orchard in Korean Autonomous Prefecture of Yanbian of Jilin Province and provide a scientific basis for reasonable fertilization,organic phosphorus fractions were determined with improved Bowman-Cole by Xiong Hengduo and Fan Yekuan,revealed the differentiation regularity of organic phosphorus components in different soil profile of apple-pear orchard.The results showed that:Compared with the different slope positions of soil in apple-pear orchard,labile organic phosphorus and moderately labile organic phosphorus flowed and accumulated in different degrees down soil horizon and slope position under influence of extermal factors(gravity,water and fertilization,etc.),moderately stable organic phosphorus and highly stable organic phosphorus were accumulated on the upslope,and were the highes.For the same soil horizon,under different season and different cultivated years,the distribution of different organic phosphorus fractions at apple-pear orchard was not the same.Mainly,organic phosphorus content of apple-pear orchard cult:ivated 11 years and 63 years declined from spring to summer,and it of apple-pear orchard cultivated 25 years and 50 years increased from spring to summer.Compared autumn with summer,organic phosphorus content of cultivated 40 years,50 years and 63 years decreased,it of apple-pear orchard cultivated 11 years and 25 years increased.Different soil horizon,organic phosphorus eomponent eontent was also different,along with increase depth of soil horizon,the content of different organic phosphorus fractions at apple-pear orchard soil and wasteland showed a downward trend in Yanbian region,Labile organic phosphorus was easily absorbed by plant,highly stable organic phosphorus was relatively stable and difficultly mineralized.Overall,total extracted organic phosphorus was low at apple-pear orchard in Hunchun and Helong,should be properly applied phosphate fertilizer.The proportion of each organic phosphorus fractions accounting for total exrracted phosphorus was different at apple-pear orchard in Yanbian region,and there is no obvious change rule with the increasing depth in the profiles,and the percentage of moderately labile organic phosphorus accounting for total phosphorus was the highest,it was the most important form of organic phosphorus in apple-pear orchard soil of Yanbian region.