Study On Change And Main Influnecing Factors Of Soil Nutrient In Suburban Beijing

This study was based on the results from the long-term located monitoring of cultivated landquality in suburban Beijing for more than20years. It studied the changes of cultivated land fertility andthe influencing factors from the aspects of fertilization, land use and regional planning, and presentedsuggestions on fertility.The main conclusions and recommendations are as follows:（1）The soil nutrient of Beijing Suburban arable land takes on a rising tendency as a whole.The average content of soil organic matter and total nitrogen is rising slowly. During themonitoring span, there are mainly two upward periods, from1992to1995and from2004to2011. Theaverage content of soil alkali-hydrolyzable nitrogen keeps steady and then rises, with an obviousincrease in2006-2011. The content of soil available phosphorus was at a higher level from1992to1995,with an average content of70mg/mg. The content of soil available potassium is on the rise, mainly inthe three periods of1990-1995,2001-2004and2009-2011.(2) The effect on arable land soil fertility made by land use type, fertilizer input and functionzoningThe types of land use have made significant influence on arable land soil fertility. Vegetable fieldhas the highest nutrient, followed by orchard and the grain field, the lowest. Fertilizer input effects soilfertility obviously: the input of inorganic nitrogen and potash fertilizers had a direct effect on thecontent of soil alkali-hydrolyzable nitrogen and soil available potassium. The variation trend ofalkali-hydrolyzable nitrogen is almost in line with that of nitrogen input, and the variation trend ofavailable potassium is almost consistent with that of inorganic fertilizer input. Function zoning of arableland effects greatly soil nutrient by deciding the mode of land utilization and the level of fertilizermanagement. The content, variation trend and rate of soil nutrient index of arable land vary significantlywith different function zoning.In the final analysis, the land use and fertilizer input and functional zoning affect the change ofarable land soil fertility by the changes of nutrient supply and demand balance. The different land usetype and function zoning resulted in planting different crops and different expected targets (includingyield), which affect the fertilization and tillage methods and then affect the soil nutrient contentand change trend.（3）Zoning fertility betterment suggestions of soil fertility in Beijing suburbCircling around the agricultural functional location and according to the results of the dynamicmonitoring of soil fertility for many years and considering the protection of water resources planningand the plain groundwater vulnerable to pollution characteristics of regional distribution in beijing,suggested that Beijing farmland soil fertility regulation should be divided into three areas, one was theoptimum fertilization area which was the urban life in city life mainly within six loop, the other was thePlain scale agriculture fertilization area which was the production of security as the core function areamainly within the suburban plain outside six loop and Yanqing Basin, the last one was the Limit fertilizer area where was the ecological conservation as the core mainly within the north, west andsouthwest mountain and hill...