| The evaluation of land soil fertility and equality of national cultivated land has been carried out by agricultural department during the period of eleventh five-year plan in order to strength the quality protection of cultivated land and to carry out the Regulations on the Protection of Basic Farmland. Now there are 374 thousand hectare cultivated land in Nenjiang county. As one of major grain producing areas and national key marketable grain base, it is needed to investigate the present situation of soil fertility and equality and make suitable plan of agricultural development on the purpose of fulfill the plan of healty and rapid development of agriculture.The second soil investigation has been carried out from 1982 to 1984. During this period, many things including the present land using situation, agricultural regionalization, soil physical and chemical characteristics, planting structure and productivity level have been changed. So it is great meaningful to promote the evaluation of soil fertility and equality of cultivated land for investigation of situation of culutivated soil, optimization of plant structure in the county, building the basement of agricultural production, developing the pollution-free and green agricultural products and promotion of advanced and practical technology.The evaluation unit of soil fertility has been set up with GIS system and ARCVIEW software which is used to quantize the data and pics while collecting the document of situation of cultivated land in Nenjiang county. Fuzzy evaluating is used as evaluation method.11 factors of soil fertility evaluation such as SOM, accumulation temperature, available P and K, depth of top soil, available B and Mo, soil texture, slope and aspect, pH are established with experts'experience according to index system of national cultivated soil fertility evaluation. The software of National Cultivated Land Soil Fertility and Quality Evaluation System V3.0 is used to evaluate soil fertility.The result shows that total area of Nenjiang county (including non-country-run farm and forestry farm) is 15.1, thousand km2, most of which are dry land and among which there are 340.4 thousand ha cultivated land for 14 county-run villeges and towns. The total area of cultivated land is divied into four grades:the first grade is 62993.3 ha,19.7%, high-yield type; the second grade is 121913.3 ha,35.2%, and the third grade is 101860 ha,32.5%, both of which are media-yield type; the fourth is 53686.7,12.5%, low-yield type; the medium and low-yield field is 277460 ha,81.5% of total area.In the whole county, the average SOM content is 53.36 g/kg, there are 51 thousand ha area of the content of which is lower than 40 g/kg, the average available P, K, B and Mo content is 69.4, 168.0,0.34 and 0.15 mg/kg.The pH values of topsoil are between 4.9 to 6.6, the average of which is 5.6. In total, the pH values which more than 6.5 account for 0.2%.99.8% of soil is subacidity.So reclamation measurements, which are including reasonable cultivation, organic fertilizers applicaton, lime application on soil surface and acid-tolerant plant cultivation, should be taken in order to increase the anti-drought capacity and recovery the fertility of soil. |
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