Potential of cultivated land quality grade improving promoted by improvable limiting factors

It is important to calculate the theoretical and realistic potential of cultivated land quality and protect cultivated land. Land consolidation is an effective way to promote quality of cultivated land by improving limiting factors. To definite the role of land consolidation in arable land quality grade, choosing some agricultural land grading factors which land consolidation can improve in time and positively is principle. Setting the theoretical top and realistic top score of different crop classification factors as targets respectively, calculating theoretical and realistic potential of cultivated land by the potential index model of the agriculture land natural quality grade is basic. Making realistic potential of cultivated land as the aim of land consolidation project would be more scientific and objective. The utilized grades could be calculated based on the natural grade by ability coefficient of land use. The economic grades could be calculated based on the utilized grades by land economic coefficient. According to the distribution of theoretical and realistic potential of natural, utilized and economic grades from townships, villages and plots, land projection project can be planned, designed and arranged in advance. The first step is to determine the improvable limiting indexes of agricultural land classification. Dashiqiao county of Liaoning province was taken as the study area based on the complement of arable grade in 2012. The study area has arable land and slope arable land which have respective improvable limiting indexes. Arable land has thickness of soil layer, terrain slop, irrigation guarantee ratio and degree of surface rock outcrop. While slope arable land has irrigation guarantee ratio, degree of salinity, drainage conditions and irrigation water source. Afterwards, we calculated the improvable theoretical and realistic degree of each selected indexes by land consolidation project based on plot respectively. Then utilized and economic grades would be calculated later. Finally with the area weighing method to summarize the results into villages and townships, we analyzed the character of theoretical and realistic potential of arable land on different scales. In villages scale we used local spatial auto-correlation method specially. The results showed that 1) Under the township scale, the theoretical and realistic potential of cultivated land quality improvement was obvious, showing high in the east and low in the west, decreasing in turn; 2) At the village level, the potential of cultivated land quality in eastern was High-High type and concentrated, in the middle was Low-Low type and distributed separately with small area, and in the west was random distribution; 3) Under the plot scale, potential of arable land quality had great promotion in eastern and middle of research area. Thickness of soil layer and terrain slope of eastern slope farmland should be improved by implementing land leveling project. Degree of salinity and drainage condition of middle farmland could be promoted by irrigation and drainage works. In conclusion, theoretical and realistic potential of arable land of research area have significant distinctions on different scales obviously, which provides the basis and technological support for developing a key cultivated land consolidation project and demarcating the boundaries of protection of cultivated land.