Evaluation of cultivated land intensive use considering land quality differences

Abstract: The aims of this paper are to illustrate the meaning and method of comparing the evaluation result of cultivated land intensive use, and to improve levels of intensive cultivated land use. We described the comparability of cultivated land intensive use, and noted that when comparing evaluation results equal consideration and correct cultivated land quality and planting structure in different districts are needed. We first calculated standard grain realizable yield in different districts based on agricultural land classification. This result can measure the quality of cultivated land. Next, we calculated standard grain actual yield in different districts by a conversion coefficient. Then we built an indicator called realizable yield utilization intensity by calculating the ratio of the standard grain actual yield and realizable yield, and this indicator can eliminate the difference on grain output because of cultivated land quality. Finally, we established an evaluation index system of cultivated land use including input intensity, use degree, production efficiency, and evaluated the level of cultivated land intensive use. Of course, the realizable yield utilization intensity was regarded as an important indicator to reflect the production efficiency. To examine this method's practical applicability, Jiangsu Province was used as an example for empirical research. The agricultural land grades in Jiangsu Province are concentrated between grade 4 to grade 8, and grade 6 is the most common, accounting for 63.77% of the land. The standard grain realizable yield is between 13 606-16 500 kg/hm2, higher output districts are mainly distributed in the area along the Yangtze River and Taihu Lake, and lower output districts are mainly located in the coastal areas of Suzhong and Subei, which also shows that the quality cultivated land is mainly distributed in Sunan. The standard grain actual yield is between 11 665-19 012 kg/hm2, and the higher output districts are mainly concentrated in the coastal areas of Suzhong and Subei, it's quite different with realizable yield from the spatial distribution point of view. The districts with higher realizable yield utilization intensity in Jiangsu Province are mainly in the areas of poor or general quality of cultivated land, and there is a lower rate in Sunan where the land has better quality. Overall, Subei has the strongest ability to achieve grain production. There are significant differences between realizable yield utilization intensity and grain yield per hectare judging from the distribution by comparison. The districts where the grain yield per hectare are similar may be very different on realizable yield utilization intensity, and vice versa. From the perspective of the province, the level of cultivated land intensive use is general, and the cultivated land use intensity in Suzhong is highest. The high intensity areas are mainly along the Yangtze River or surround the Taihu Lake and in some areas of Yancheng and Xuzhou. The distribution of cultivated land use intensity is more balanced in Nanjing, Changzhou and Huai'an, and it has a large difference in Wuxi, Suzhou and Yancheng. The level of cultivated land intensive use in Sunan is extremely unbalanced. The results of the evaluation are more accurate after eliminating the effect of cultivated land quality differences, and the indicators that we used also can eliminate the effect of planting structure differences to a certain extent. All indicators used on evaluating need to be corrected according to cultivated land quality and the planting structure of different districts, and these theories and methods will be the direction that we continue to study.