Study On Spatial Variability Of Land Productivity In Nutrient Barren Area Of Heilonggang

To ensure national food security is a prerequisite of building a socialist harmonious society. productivity is the core and key of Farmland ecosystem, the growth of China's food supply is based on a further increase when the grain yield is already close to or above the world average, so studying on regional agro-ecosystem productivity and Variability of spatial distribution and characteristics of productivity, analysising the controlling factors of the land productivity spatial variability, is important to the improvment of the Agro-ecosystem productivity. In this study, taking the Xiong County Land of Heilonggang Valley for ecosystem study, by analyzing the theory and content of the land productivity spatial variability, the study analysised the feature of Xiong County land productivity spatial variability through different levels and builded evaluation system of land productivity and land productivity variation in field Scale, And then studyed the spatial distribution and controlling factors by using the methods of field survey, laboratory analysis and map address. The main conclusions are as follows:(1) The land productivity was analyzed from three aspects of trend, volatility and stability. Productivity trends, the average growth rate of total grain output is 4.05% and it is not stable development, the growth rates has declined since 2000; The villages and towns of the average annual growth rate more than 4.00% is Mibei and it's the highest in Xiongxian county.The development conditions of Daying town is poor and total grain output grew for the negative trend by the -0.28%. In the Volatility of land productivity, Xiong County's total grain output shows the 5yeaes, 10 yeaes and 15 yeaes, three time scale fluctuations in the cyclical changes in characteristics exist, the spatial distribution of fluctuations in intensity is weakening from the southeast to the northwest, the fluctuations of the maximum intensity is 0.59 in Beisha town and the minimum is 0.12 in Zangang town. The Stability variation showed a feature that it is weaken gradually from southeast to northwest, the highest stability of land productivity is 0.3968 in Xiongzhou town and the lowest is Beisha town which is Less than zero,is the worst areas in cultivated land productivity stability in Xiongxian County.(2) The study established a field scale evaluation index system of land productivity, Ascertained the spatial distribution and the main control factors of land productivity in Xiongxian. Xiong County pay the highest standard grain of 891kg/acre, the minimum is only 432kg/acre, and the standard grain within the different levels of distribution was distributed by poor state flower,the concentration of Land Quality is Higher. Drainage conditions, organic matter, irrigation guarantee rate, total nitrogen, available nitrogen and potassium is the control factors of volatility of productivity.With the productivity rising, Human factors and natural factors on the productivity appeared alternately phenomenon, Concrete expression is: Human factors and natural properties of soil is interacting in the relatively low productivity areas, dominated by human factors higher productivity areas.(3) It reveals spatial variability rule of land productivity from further cultivated field scale for land productivity variability in Xiong County.The distribution area of one class variable region ([0,0.10]) 9722.28hm2 is the biggest ,and accounts for 31.09% in the total area of cultivated land, 2 class variable region ((0.10,0.18]) and 3 class variable region ((0.18,0.25]) are similar, It is respectively 7889.41hm2 and 7862.33hm2 and accounts for 25.23% and 25.14%; 4 class variable region ((0.10,0.18]) is the least and only accounts for 18.54% .The controlling factors of productivity space fluctuations in the Productivity stability contain mainly total nitrogen, soil configuration, salinization conditions and organic matter.The effect of human is the biggest for productivity in farmland ecosystem productivity stability, it is similar for Natural properties of soil stability factor in the middle with the very human factors.(4) High-yield farmland ecosystem productivity (grain yield high standard) is not necessarily high stability, and low output (standard grain yield is low) is not necessarily less stable in Xiong County. It exist the cross-cutting areas,that certains cross-cutting. High stability and high yield of low stability were the two largest area and 68766.61hm2 6836.73hm2,high yield of high stability and low yield of high stability respectively is 6836.73hm2 and 68766.61hm2, accounts for 43.85%in the total area of cultivated land throughout the county, The higher level and stability of farmland ecosystem productivity can maintain high steady-state by Strengthening labor management, controling fertilizer, improving irrigation facilities and so on.