Cultivability evaluation and conservation strategies of land resources in China

Only one third of the world average can be found in the per capita farmland in China. Furthermore, a large number of high-quality cultivated land has been occupied and replaced by low-quality farmland with the continuous development of urbanization in recent years. The unsuitable or uncultivable distribution of farmland in areas (such as beaches and mountains) has posed a serious threat to the national security of farmland. Great challenges have also been put the national food security in the context of emergencies, such as epidemics and disasters. It is a high demand for the high level self-sufficiency in food production under a large population during this time. In this study, a new understanding was offered to protect the farmland system, in order to change the perception from the farmland system to the cultivatable land. The ecological niche model and geographic information system (GIS) were used to measure the scale size and spatial distribution of cultivatable land, current farmland, and construction land. Firstly, the amount of cultivatable land was sufficient with the outstanding difference in spatial distribution. The cultivatable land was sufficient in the east of Chinese Heihe-Tengchongn line, where the area was approximately 2.05 times that of the current farmland. Secondly, there was the uneven quality of current farmland, where the less current farmland was distributed in the highly cultivable areas. There was an outstanding location difference in cultivatable land quality. The cultivatable land showed a hierarchical level in different areas, where the quality gradually decreased from the southeast to the northwest of China. Thirdly, there was a spatial mismatch between the cultivatable land and the current farmland. About 16.83% of the current farmland was in the unsuitable area for cultivation. The current farmland was distributed in the uncultivable areas, where the low quality of farmland led to low production in the essential goal of farmland protection, due to the mismatch between the cultivatable land and current farmland. The proposal of cultivatable land was provided the direction for the transformation of farmland protection. The "grain-land" mismatch rate of farmland also reduced resource consumption and environmental pollution. The cultivatable land grading and zoning protection were carried out to appropriately adjust the layout of current and new farmland, in order to realize the fertile land for grain use and storage. At the same time, the protection of cultivatable land can greatly contribute to the cultivatable capacity of the land, in order to avoid the encroachment and squeezing of the cultivatable land, due to urbanization. The retention of enough land can be expected to fully meet the possible future farming needs. Therefore, sufficient cultivatable land can be provided in time for agricultural production.