Comprehensive index model building of cultivated land yield and productivity based on improved agro-ecological zoning method

Abstract: Study on the relationships between grain production and cultivated land productivity and its regional difference is of great significance for food security. Besides, it is also important for finding regional potential yields of grain, improving the utilization efficiency of cultivated land resources and achieving the regional increase of grain yield. In this paper, on the basis of agro-ecological zoning (AEZ) model, a new method was proposed to calculate the cultivated land productivity under cultivated land quality modification. Furthermore, the modification of cultivated land quality was based on a new concept that the quality of cultivated land was not only affected by natural factors but also by artificial factors such as irrigation canals, greenhouse, nursery factory, mechanical facilities and its supporting service station. By discussing the conceptual system of cultivated land integrated productivity which took the potential quantity of cultivated land and the quality index of cultivated land into the consideration, we proposed that comprehensive productivity of cultivated land was the maximum sustainable production capacity for food under the certain economic and technological conditions, and it was strongly affected by the quality and quantity of cultivated land. Additionally, according to the concept, we built a model which can reveal the relationship between grain production and cultivated land productivity. This model was made up of comprehensive yield and productivity index of cultivated land (CLYPCI), cultivated land quality productivity index (CLQLPI), and cultivated land quantity productivity index (CLQNPI). The CLYPCI was used to measure the efficiency of cultivated land grain production and to reveal the relationship between actual output of grain and cultivated land productivity in a particular area. The CLQLPI was used to describe the average output efficiency of a regional cultivated land. The CLQNPI was used to measure the degree of exploitation and utilization of cultivated land in terms of quantity. This model was constructed based on the improved AEZ model, so it was only suitable for researching the relationship between grain production and cultivated land productivity at large or medium scales. At last, in this paper Quzhou county was used as a case study for model validation. The value of CLYPCI, CLQLPI and CLQNPI was 0.16, 0.31, 0.99, respectively in Quzhou. The results showed that the output efficiency and the average development level of cultivated land were not high in general. The potential of increased quantity of cultivated land was low, but the potential of increased yield of cultivated land was high. Compared with the cultivated land comprehensive productivity (CLCP), the CLYPCI value of different towns was reduced with CLCP which was sorted from the largest to smallest except Disituan town. The output of cultivated land was proportional to its productive capacity by comparing CLCP and CLYPCI of various towns. In addition, the value of CLQLPI and CLQNPI of different towns were very similar. The CLQLPI of 10 towns fluctuated around 0.31 which was the average value of CLQLPI of Quzhou. The CLQLPI in Yizhuang was the highest. The CLQNPI of 10 towns fluctuated around 0.99 and there were six towns whose CLQNPI value was 0.99. The CLQNPI of Yizhuang was also the highest. There was little chance to increase the quantity of cultivated land for Yizhuang.