National agricultural land grading distribution law based on conversion from provincial level to national level in Chongqing

This study was to validate the correctness of the national agricultural land grading integrated method, and the correlation of integrated national agricultural land grading with provincial natural factors. With the statistic and comprehensive analysis, we took Chongqing provincial agricultural land grading achievements as a case to analyze the national agricultural land grading distribution law. The results showed that the different agricultural land grading area rate of the national level was similar to that of the provincial level grading, after provincial fruits was converted into national fruits, in addition, the national agricultural land grading integrated method based on the land productivity was valid. The results also showed that the national irrigated land natural, use and economic grading were higher than that of dryland within the same standard cropping system. Compared with the different standard cropping system, the average national agricultural land grading in Yuxi low hill area and Yudong middle mountain were higher than that in Yuzhong low mountain and Yudongbei middle mountain. The national agricultural land grading was positive correlation with such natural factors as soil depth and soil organic matter contents, but was negative correlation with elevation. The national agricultural land grading distribution law not only inherited the order of the provincial agricultural land grading, but also in accord with the agricultural land productivity. The national agricultural land integrating method provides a scientific basis for the agricultural fruits conversion from provincial level to national level.