Distribuation Characteristics Of Soil Aggregate And Organic Phosphorus In Aggregate Soil Of Apple-pear Orchard In Longjing City

Yanbian area is an eugenic area of apple-pear production,its peculiarity of climatic conditions and endemism of pear species differ from other orchard ecosystem in our country,which makes the quality of soil in Yanbian become the emphasis of our research.Longjing is located in the southeast of Yanbian Korean Autonomous Prefecture,and is also the major producing area of Yanbian’s apple-pear.This text takes the soil of Longjing’s apple-pear orchard as the main object of study,Select planting years for 11,25,40,50,63,and arranges sections in spring,summer and autumn,2015,made a soil layer according to 0-20cm,20-40cm,40-60cm to gather the soil samples,measure the content of soil aggregate by dry-select method,determinate composition of organic phosphorus in soil aggregate by modified Bowman-Cole.Research results can furnish scientific basis for soil phosphorus cycle research and rational application of fertilizer for Yanbian’s apple-pear orchard,and remedy the deficiency of research about organic phosphorus distribution in soil aggregate.The results of the study are as following:1.In the early stage of orchard reclamation(planting 11 years),the content of<0.25mm aggregate was higher,after that,with the increase of planting period<0.25mm aggregate content decreased,0.25mm-10mm aggregate content showed an increasing trend.The fractal dimension was the smallest in orchard reclamation,and there was a decreasing trend in planting orchards for 63 years compared with 50 years.<10mm aggregates in 0-20cm soil layer,1-0.5mm as the first grade aggregate advantage.Below 20cm soil layer,5-3mm as the first grade aggregate advantage of orchard soil.With the layer increase the contents of>10mm and<0.25mm aggregates decreased.The mean weight diameter and geometric mean diameter increase with the increase of soil layer.The fractal dimension decreases with the increase of soil layer.2.The organic phosphorus in the aggregate of apple pear orchard in Longjing area is mainly middle active organic phosphorus content,and the middle active organic phosphorus>high stable organic phosphorus>active organic phosphorus>middle stable organic phosphorus3.The content and concentration of organic phosphorus in each form showed a wavy change with the planting period.After 25 and 40 years,the content of organic phosphorus and the stocks were higher,and the content in the garden was relatively small for 50 years4.Organic phosphorus content in 1-0.5mm,0.5-0.25mm and<0.25mm content in grain size increases with the decrease of the particle size,and Organic phosphorus storage with the decrease of particle size decreases.The organic phosphorus in the in 0-20cm layer in the 1-0.5mm aggregate for the first advantage.In 0.5-0.25mm is the second advantage;In 20-40cm and 40-60cm layers the 5-3mm aggregate organic phosphorus storage is the highest.In three layers,the aggregate organic phosphorus storage in<0.25mm aggregate is the minimum.In summary,planting fruit trees are favorable to the formation of 0.25-10mm aggregates,planting the longer form 0.25-10mm aggregates more,and young(25 years of orchard planting)tend to form small aggregates,young people and adults(planting 40 years)make aggregate structure more complex,the accumulation of organic phosphorus.More than the lower and upper orchard soil,organic easy occurrence in larger particle phosphorus..