| In this research, the study area is four towns of Datong District in Daqing city, four towns were chosen for the Laoshantou village, Bajingzi village, Taiyangsheng township and Shuangyushu village. Soil fertility survey was conducted in the area of arable land in four towns, and thus the evaluation could be performed. Not only this investigation is significant and meaningful to support the quality improvement and utilization for Four towns of arable farmland plaque, precision fertilization and achieve comprehensive benefits of agricultural production. But also it is necessary to peasants to achieve the sustainable use of soil fertility. At the same time, some help could be provided for the guides, output and yield.In this experiment, for the study object is farmland soil of four towns in Datong District, soil nutrient content in Datong District was investigated in time. At first, 12 indicators were chosen to evaluate cultivated land productivity using the Delphi method, and then the weight of each factor was determined by AHP(Analytic Hierarchy Process). These factors were classified into three basic types: the basic soil conditions, physical properties and nutritional conditions. The types include some sub-items respectively: the p H, topographic position, irrigation guarantee rate, effective soil texture, barrier layer, potassium, organic matter, phosphorus, zinc and soil salt content; then the fuzzy mathematical theory was used to calculate the degree of membership for each sub-item; finally, the spatial variability of soil nutrient was studied by the support of GIS and computer technologies, and using the Krigng interpolation method to generate the thematic map of cultivated land fertility evaluation. The map can help directors to understand the spatial distribution of soil nutrients, soil fertility and obstacles in the study area, meanwhile it can provide some suggestions to the section of agricultural production and land management. The main results obtained in this paper are summarized as follows:1. Spatial variability of soil nutrients. the spatial variability studied of these sub-items(soil pH, potassium, organic matter, phosphorus, zinc and effective soil total salt content)was analyzed before the evaluation of soil fertility, and Spatial variability maps were made by using GIS software. It could be showed clearly by the pattern of electronic maps. The results show that the coefficient of variation of soil pH <10%, it presented weak variability; the range of other sub-items was between 12.85%-38.15%, showing a moderate variation; From semi-variance analysis, the nugget values of organic matter and available potassium are pretty high, the explanation of this phenomenon showed that these sub-items were influenced by the random factors; And the nugget values of Soil pH, available zinc, phosphorus, and total salt content close 0, indicating that less affected by random factors. From the nugget effect, the maximum value of each nugget effect of soil nutrients was 22.1%, less than 25%, indicating strong spatial correlation was existed, soil nutrients influenced by structural factors.2. Analysis of soil nutrient status. From each spatial distribution of soil nutrients, soil in four townships is alkaline and high degree of salinization, crops will be moderately affected. There are some similarities in the spatial distribution of each soil nutrient factors; it is consider that the trend was gradually improved from the West to the East. From the results of the spatial distribution of organic matter and available Zn, soil conditions of Bajingzi village have obvious advantages. Within the higher range of indicators in four townships, spatial distribution of potassium, phosphorus content were scattered, but the overall trend is more consistent.3. Evaluation of cultivated land productivity of four towns. Using GIS software to draw thematic maps of cultivated land fertility evaluation results and collect statistic data which related to the arable land and then five grades were classified by using equally spaced method. The results showed: The first grade land area is 9987.39 hectares in four township, accounting for 29.33% of the total area of basic farmland; second is 4727.15 hectares, accounting for 13.88%; third-class area is 8584.77 hectares, accounting for 25.21%; the forth is 10,415.27 hectares, accounting for 30.59%; the fifth is only 336.12 hectares, accounting for 0.99%. Each grade area showed the area order is the forth> the first>the third>the second > the fifth.4. The spatial distribution of farmland for each grade. The first grade land mainly distribute in the Laoshantou village, an area of 7181.29 hectares, accounting for more than half of the rural basic arable land, and each level has distribute in this town; The second and third grade land distributed in the four townships, and the Laoshantou village and Taiyangsheng town occupied by the larger area; The forth grade land mainly distributed in Shuangyushu Township, an area of 8947.38 hectares, accounting for a percentage of the total area of rural basic farmland 91.3%; The fifth grade land only distributed in Shuangyushu Township and Bajingzi Township, an area of less.5. The arable soil Obstacles mainly in soil pH, soil salinization, soil fertility insufficient and irrigation guarantee rate is very low. Its main improvements are: ① Noting irrigation methods, crop year after planting and fertilizer application may be change the case of soil pH and soil salinization; ② If soil was alkaline conditions, it is not easy to the use plant mineral elements sufficiently, it should be noted that constant element fertilizer combined with the use of trace element fertilizers and improved soil pH; ③ The soil organic matter situated the middle edge of the extent, it is recommended to applied organic fertilizer, manure, straw and other measures to compensate the consumption of organic matter; ④ It should strengthen the construction of irrigation facilities to improve irrigation guarantee rate, and establish the soil and water conservation measures. |
PDF Full Text Request