Spatial distribution characteristics of soil phosphorus in the plow layer soil of the main farmlands in Hainan Island
Investigating the spatial distribution characteristics of phosphorus in farmland plow layer soil can help understand the accumulation status of soil phosphorus,providing a basis for the judicial application of phosphorus fertilizer in farmland.From the main farmlands in Hainan Island 2 386 soil samples were collected from the plow layer(0-20 cm)and their soil indexes such as total phosphorus content,available phosphorus content,organic matter content,etc.,in the soil were determined.The spatial autocorrelation of the total phosphorus and available phosphorus in the soil was analyzed by using geostatistical methods,and ordinary kriging interpolation was used to predict the spatial distribution of total phosphorus and available phosphorus in the plow layer soil of the main farmlands in Hainan Island.The results indicate that the plow layer soil in the main farmlands of Hainan Island has relatively high and highly variable contents of total phosphorus and available phosphorus.The range of total phosphorus content in the soil is between 0.06 to 4.61 g·kg-1,with 40%of the soil samples exceeding the first level(>1 g·kg-1),with a mean of 1.02 g·kg-1 and a coefficient of variation of 64%;the range of available phosphorus content in the soil is between 3.16 to 478.88 mg·kg-1,with 72%of the soil samples exceeding the first level(>40 mg·kg-1),with a mean of 106.51 mg·kg-1 and a high coefficient of variation of 91%.The Nugget/Sill ratios of total phosphorus content and available phosphorus content are 0.918 and 0.928,respectively,indicating weak spatial autocorrelation mainly influenced by random factors.The kriging interpolation prediction map shows that the plow layer soil has higher total phosphorus content in the soil,mainly between 0.8 to 4.61 g·kg-1 in the north and south of Hainan Island,and relatively lower total phosphorus content,mainly ranging from 0.4 to 0.8 g·kg-1 in the east and west.The overall available phosphorus content in the soil is relatively high,with the available phosphorus content in the north ranging from 3.16 to 478.88 mg·kg-1,exhibiting uneven distribution,with the highest available phosphorus content reaching around 400 mg·kg-1 in Haikou City and Chengmai County.In the south the available phosphorus content in the soil is concentrated in between 90 to 240 mg·kg-1,while in the east and west it is relatively lower,concentrated in between 20 to 90 mg·kg-1.Overall,the contents of total phosphorus and available phosphorus in the plow layer soil of the main farmlands in Hainan Island are at a relatively high level,highly influenced by fertilizer application.The water bodies surrounding the main farmlands face significant pollution risks,indicating the need to control the application of phosphorus fertilizers in agricultural production.
Geographic Information Systemavailable phosphorusgeostatistical analysisspatial distributionland use type