| This paper took Shangluo city of ShanXi province as the research object.Organic matter,available phosphorus,available potassium,total nitrogen and pH were selected as five soil nutrient elements.Traditional statistic method,geo-statistic method and GIS information technology were combined applied in this thesis.The basic characterisitics,spatial distribution and influencing factors of each nutrient element were analyzed,and the regional cultivated land force evaluation was carried out,The main results were as follows:(1)In this study,the average content of soil organic matter was 17.97g/kg,and the average content of available phosphorus was 19.22mg/kg.The average content of available potassium was 118.05mg/kg,and the average content of total nitrogen was 1.05g/kg.According to the standard of nutrient content of the second soil survey in Shaanxi province,the content of these four nutrient elements was at medium level.The pH value is 7.15,showing a weak alkalinity.The coefficient of variation of the five nutrient elements was from large to small:effective phosphorus>,potassium>,whole nitrogen,>organic matter>pH.Among them,pH showed a weak variability,while the remaining nutrient elements were all at moderate variation.(2)In this study,the spatial autocorrelation of soil nutrients was examined by the optimal semi-variance function and Moran's I index.Among them,the optimal semi-variance function model of total nitrogen was spherical model,while the optimal semi-variance function model of organic matter,effective phosphorus,available potassium,pH were index model.The order of block gold coefficients from large to small was:effective phosphorus>organic matter>instant potassium>pH>total nitrogen.Among them,the block gold coefficient of effective phosphorus was 75%,which showed weak spatial autocorrelation.The remaining four nutrient elements were between 25%and 75%,presenting medium spatial autocorrelation.Meanwhile,Moran's I index of five nutrient elements was 0.183~0.556.The normalized Z values were positive and greater than 1.96,having Strong spatial clustering.The sort of degree of aggregation was same as block gold value.(3)The spatial distribution of the five soil nutrient elements in this study was different.The organic matter was significantly higher in the northeast than in other areas.The available phosphorus was distributed in the space with broken patterns,and the eastern content was higher than that in the west.The distribution of available potassium in the northeast was with broken patterns.And the change in southwest was relatively smooth with a relatively strong continuity.The spatial regularity of total nitrogen was obvious,and the content of the northeast corner was obviously higher than that of other regions.The pH changed heavily in the northeast with a bulk or clastic distribution.The overall spatial distribution pattern is the eastern partial acidity,the western partial alkalinity.(4)In this study,the correlation between four topographic factors and soil nutrient elements was different.There was a significant correlation between elevation,slope,aspect,fluctuation and five nutrient elements(p<0.01).Among them,the correlation coefficient between the fluctuation degree and each nutrient element was greater than the slope.The slope direction was significantly positively correlated with available phosphorus and total nitrogen,and was negatively correlated with p H,and was not correlated obviously with organic matter and available potassium.Soil type and geomorphic type had significant influence on the spatial pattern of soil nutrients.(5)The total area of cultivated land in this study was2240.98km~2.Among them,the fifth grade cultivated area was the largest,the area was 743.39km~2.accounting for 33.17%of the total cultivated land.The first grade cultivated areawas 121.37km~2.The second grade cultivated area was 138.17km~2.The third grade cultivated land area was 226.95km~2.The forth gradecultivated area was 730.18km~2.And the sixth grad cultivated area was 280.93km~2.These wer accounting for 5.42%,6.17%,10.13%,32.58%,12.54%of the total cultivated land respectively.Among them,the first gradeand second grade cultivated land was mainly distributed in the river terrace,which was flat,with abundant sunlight,abundant water supply and perfect infrastructure.And the soil types were mainly brown soil,new soil and yellow brown soil.The tertiary cultivated land had a large distribution in the hilly area,and the soil type was mainly yellow brown soil.The fourth,fifth,sixth grade cultivated land were concentrated in mountainous areas with high elevation,high fluctuation and low human activity.And the soil types were mainly yellow brown soil,coarse bone soil and brown soil.Soil type and geomorphologic type had significant influence on the potential of cultivated land. |
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