| Soil is a continuous variant in space-time, which has high degree spatial heterogeneity. Under the long-time actions of human,the circulation of materials and soil fertility status of cultivated land have changed greatly. So there is an important realistic significance to study on spatial viability of extent soil fertility in condition to figure out artificial adjustment, soil fertility under directional cultivation for improvement of soil environment and promoting continual development of agriculture and society.In this study, the ways of investigating in outdoor typical field and analysis in laboratory were used, and the traditional statistics and geostatistics were used to analyze and treat the data. The variogram analysis of geostatistical, Kriging estimation method, binary linear model and principal component analysis were used to study the soil nutrition spatial variances and distribution characteristics of cultivated lands in different counties of Saiqi town. The main results are as follows:1) In all cultivated lands, the content of alkali-hydrolyzable nitrogen of baidi land was highest, and the content of available phosphorus of wusha land was highest with the similar trend to rapid available potassium. The content of organic matter showed high values with the highest lanjiaoni land and the lowest huishali land.2) The coefficient of variation of the soil nutrient factors was between 0.088 and 1.086. Available phosphorus showed high variant with the value of 1.086, and pH showed weak variant with the value of 0.088, except the other nutrients showed medium variant. The content level of nutrients showed medium level besides available phosphorus with poor level. The related coefficients between pH and alkali-hydrolyzable nitrogen are higher with significantly negative relations.3) The nugget of rapid available potassium was lowest with 7.9% and showed extreme space correlation. The nugget of alkali-hydrolyzable nitrogen, available phosphorus, pH, organic matter was 14.1%, 24.5%, 18.5% and 13.5% respectively. These results indicated that the description of soil properties in the region has a strong space correlation. Judging from the spatial correlation distance, the soil variance tune ranged was 480-7410m, dependence space showed available phosphorus> alkali-hydrolyzable nitrogen>organic matter>rapid available potassium> pH. From the 3-D soil nutrient information pictures, the alkali-hydrolyzable nitrogen is variable mostly at southeast-northwest direction, the rapid available potassium is at northwest- southeast direction, organic matter is at west-east direction, available phosphorus is at east-west direction, and pH shows little fluctuation.4) The bivariate regression model was used to simulate the relation between soil nutrients and geographic position, the results were as follows: the contents of alkali-hydrolyzable nitrogen, available phosphorus, rapid available potassium and organic matter have significant correlation with geographic position. As compared, the content of pH value has no significant correlation with geographic position.5) Principal component analysis showed that first principal component had significant positive correlation with alkali-hydrolyzable nitrogen and organic matter which may reflect the ability of continual fertility of lands, as second principal component had significant negative correlation with available phosphorus which may reflect the inhomogeneous distribution of phosphorus in lands. Meanwhile, factor loading pattern was calculated to achieve eigenvector matrix of principal component and the equations of first, second and comprehensive principal component were showed as follows: F1 = 0. 559x1-0.278x2-0.410x3-0.363x4+0.557x5 F2 = 0. 198x1+0.748x2+0.366x3-0.504x4+0.116x5 F = 0 .440x1 +0.059x2-0.155x3-0.409x4+0.412x5The scatter pot of first and second principal component was drawn and soil fertility of lands was analyzed as follows: the counties which had a long cultivating period maintain well alkali-hydrolyzable nitrogen and organic matter. On the contrary, the counties which manure chemical fertilizer have high content of available phosphorus and rapid available potassium. |
