Study On Cultivated Land Quality Evaluation And Prediction Of Organic Carbon Storage In Nongan County

The main purpose of grading quality of cultivated land is to quantify the amount,quality and distribution of arable land for science. Efforts to achieve farmland management of according to the law, scientific, rational and unified. Realization of arable land occupation and retrieval. Management of land to the quantity, quality, ecology coordinated management to achieve the purpose of scientific use. Farmland grading is based on massive data including administrative map, land use map, soil map,hydrological geological geomorphological map and farmland environment yield map. According to the evaluation objectives and requirements,having Several categories of partition, design of soil profile(fixed point) and farmland property monitoring points(dynamic) and sample analysis process. Especially the vertical distribution and density of soil organic matter and reserves are one of the most important attributes of quality evaluation. These data through GIS data standardization and converted to vector and raster data Analysis of a variety of very complicated and realize the classification and quality evaluation of target finally.In this paper, based on ArcEngine development platform, visualBasic.NET language method, agricultural land classification gradation theory and collection procedures of agricultural land classification gradation, develop and design of the cultivated land quality grading system. On the basis of achieving data entry, editing, query and output functions,it also achieved calculation of nature quality points, nature gradation index, utilization gradation index,economy gradation index, nature gradation, utilization gradation and economy gradation and provides technical support.for County farmland quality grading evaluation.Evaluating the quality of cultivated land grading in Nong’an County by using the system,the results show that Nongan County cultivated land quality gradation distribution range from 8 until 13,a total of 6 gradations. Nature gradation is mainly concentrated in 9-12.The average natural gradation is 11.21. Utilization gradation is mainly concentrated in10-12,the average utilization gradation is 11.06.Economy gradation is mainly concentrated in10-12,the average economy gradation is 11.33, three gradations are stable in 11.The quality of cultivated land and soil fertility are closely related, and the core of soil fertility and soil organic carbon is the problem. The quantity and quality have a direct impact on farmland ecological functional strength. Therefore the measure of soil organic matter density and storage has important reference to the evaluation of the quality of cultivated land. At the same time, sampling Jilin Nong’an 50 typical arable soil profiles and determinating organic carbon. And using the index model, logarithm model, exponential model and S curve model to fit the profile of organic carbon data,discovering significant differences between the four models fitting. Combined with topsoil organic carbon of historical data(7600) of 1m Nong’an county farmland soil organic carbon density and storage of estimation and evaluation The index model R2 is more than 0.93. Logarithm model R2 is stable for 0.88. Exponential model R2 is between 0.7-0.8.The S model R2 is more than 0.97.In four models fitting, S model has the best fitting. On this basis, to further improve the S model, using inverted S-curve model Y=Ki/(1+e)xba - study the vertical distribution of organic carbon. Using of top-soil organic carbon(SOC) data analyzes of soil organic carbon density distribution and its reserves.The results show that soil organic carbon can use topsoil organic carbon content(Ki) for the basic parameters to build the vertical distribution model. Its purpose will establish contact top-soil organic carbon data with the vertical distribution of soil organic carbon. Thus, some top-soil organic carbon can be used to estimate and evaluate soil organic carbon density in certain depth. The organic carbon was estimated reserves 49512.7536×106kg.The 0-20 cm organic carbon reserves of 14140.46×106kg, accounting for 28.58 of the total. The 20-40 cm organic carbon reserves of 13110.29×106kg, accounting for 26.48 of the total. The 40-100 cm organic carbon reserves of 22251.03×106kg, accounting for 44.94 of the total.