Spatial Difference And Influencing Factors Of Available Phosphorus Enrichment In Cultivated Land Of Fujian Province

Taking the top soil(0～20 cm)of farmland in Fujian province as the research object,soil properties data were analyzed by using 36777 samples from the Second Soil Survey in 1982,200322 samples from farmland productivity evaluation in 2008 and 20477 samples from soil testing and fertilizer recommendation in 2016.On the basis of establishment of spatial database of soil available phosphorus(P)from 1982 to 2008 and from 2008 to 2016 in Fujian Province by GIS and Kriging spatial interpolation techniques,the spatial variation and causes of available P enrichment in cropland soils in Fujian Province from 1982 to 2016 were analyzed;and the main influencing factors of available P enrichment in arable land in Fujian province from 1982 to 2016 were also explored.The division of available P enrichment with varying degree of arable land in Fujian province from 1982 to 2016 had been finally zoned using the dynamic clustering analysis model.The results could provide a scientific basis for the development of reasonable phosphate fertilizer management measures in Fujian Province.The main findings were as follows:1.The available P in arable land in Fujian province showed enrichment in general from 1982 to 2016,with the average enrichment amounted to 31.57 mg·kg-1,and the total areas accounted for 97.24%of the total cultivated land.2.Among the horizontal spatial differences of available P enrichment in arable land Fujian province,from 1982 to 2016,the available P enrichment of farmland during the periods were significantly higher in the south subtropical region than those in the mid-subtropical region;and the availability of available P in the three cropping system periods were higher than that in other planting areas.Simultaneously,with the increasing of the distance from roads and residential areas,the degree of available P enrichment decreased.3.In terms of different altitudes,soil under an elevation of 200m showed the highest available P enrichment from 1982 to 2008,reaching31.84 mg·kg-1;and the available P enrichment in the soil at other altitudes was lower.From 2008 to 2016,the available P enrichment of cropland soil increased firstly and then decreased with the increasing of elevation,and the highest available P enrichment was shown in the cropland soil with an elevation of 600～800 m,reaching 22.79 mg·kg-1.4.During 1982-2016,available phosphorus highly enriched areas of arable soil in Fujian Province were mainly distributed in the eastern and southern regions,while the moderately enriched and slightly enriched areas were mainly distributed in the central and western regions of the province.In addition,the available P enrichment level in arable land during 2008-2016 was lower than that in 1982-2008.5.The grey slope correlation analysis showed that the annual mean P fertilizer application rate,annual mean precipitation,and soil pH were the key factors(correlation coefficient absolute value>0.74)affecting available P enrichment in cultivated land of Fujian Province;the annual mean temperature,soil organic matter,clay content,silt content and sand content had a low impact on available P enrichment in cultivated soil.(the correlation coefficient was between 0.68～0.74),and the effect of soil sand content on the available P enrichment in cropland soil was the lowest(the absolute value of the correlation coefficient was only 0.68).