Spatial And Temporal Variation Of Soil Available Phosphorus In The Field Of Yizheng City In Jiangsu Province

The spatial-temporal variation of the field of county has been analyzed for Yizheng city of Jiangsu province by making good use of five phases of general soil survey data from1982to2005as a case study, using Geo-statistics methods and GIS technique to analyze the soil available phosphorus level, the spatial-temporal variation characteristic and the spatial distribution. Furthermore, discussing the various physiognomy types, various soil classification, various soil parent materials and so on, which have the influence on the temporal-spatial heterogeneity of soil available phosphorus, finally, analyzing to change the main reasons and the corresponding countermeasure. The results described as follows:Compared with the available phosphorus data of various physiognomy types indicated that the content of available phosphorus in the area of hill and mesa were obvious lower than that in the areas of floodplain and plain. Significant difference for soil properties are found in different subgroup soils which the content of the available phosphorus rank in the following order:yellow brown soil> various subgroup paddy soil> grey chao soil. Similar methods are presented in different soil parent materials too, which showed that new alluvial deposit soil from Yangtze River and Xiashu Loess and alluvial deposit soil from Yangtze River were low. In addition, statistics are performed to determine the content of the available phosphorus in different soil texture. The result followed that medium loam soil, heavy loamy soil and light clay soil were higher than light loam soil.The spatial distribution variations are found in different years. All theoretical model conforms to the exponential model; the ratio of nugget to sill of available phosphorus changed from62.96%to89.10%, which was found that spatial heterogeneity of available phosphorus showed low spatial auto-correlation in different years, however, the degree of the spatial heterogeneity in2005were higher than in1982and in1989.The findings discovered that the available phosphorus average content in1982were lower than in1989from7.91mg/kg to5.78mg/kg and kept rising gradually to0.30mg/kg in2005, the content of the available phosphorus between the year of1982and2005was almost the same. Analysis the content of soil available phosphorus in2005showed that45.44%area had achieved the Ministry of Agriculture soil available phosphorus grade high level standard.Based on the data of the survey and stationary monitoring of soil fertility, grain output, fertilizer investigation and so on from1980to2005, and make use of fertilizer investment situation investigation of182farmers in Yizheng region, which were concluded that the improvement of the available phosphorus in soil was mainly contributed to the more application of fertilizers, the changes of tillage, government policy, crop system and soil management.