Abstract:
The northeast black soil region has been one of the most important main grain producing areas and commodity grain production bases in China. A great task is to realize the national grain supply and security. The typical black soil has the excellent soil characteristics and high fertility. However, the high-intensity utilization mode of arable land is widely used in the grain production under the ever-increasing demand with the acceleration of industrial development and urbanization. Although this approach can improve the grain output in a short period of time, the cultivated land pressure (such as shallower surface layer and quality decline) is gradually appeared in the black soil area. Therefore, it is very urgent to protect the black soil areas, as issued by the Outline of the Plan for the Protection of Black Soil in Northeast China (2017-2030) in 2017. This study aims to clarify the cultivated land pressure in the black soil area of Northeast China under different scopes of food security. The 21 typical black soil counties and districts were selected using the statistical data from 2004 to 2019. A modified model of cultivated land pressure index was established to calculate the cultivated land pressure index. The grey-BP network combined with the forecasting model was used to predict the change trend of cultivated land pressure in the next five years. Some suggestions were also proposed for the black land protection. The results show: 1) The cultivated land pressure was generally better in the typical black soil area of Northeast China from 2004 to 2019. But, there were still some areas with the "false security" phenomenon, due to the high intensity of cultivated land use pattern. The severe pressure constraints were found in the black soil of the cultivated land. The dynamic change of cultivated land pressure was negatively correlated with the quality of cultivated land, actual per capita cultivated land area, as well as social and economic development level. Therefore, the cultivated land pressure gradually increased with the expansion of food security. 2) A typical northeast black soil area of cultivated land was found to effectively relieve the national pressure from 2020 to 2024. But, the low and medium pressure level was observed in the Nehe, Changtu counties, whereas, the Baiquan county was in a high pressure rise. The Yian County was depended mainly on the rural social and economic development. Specifically, the pressure was in the good condition before 2023, but the subsequent trend indicated the pressure warning. 3) The pressure of cultivated land can be expected to represent the pressure of food security, but the pressure of food security cannot accurately reflect the pressure of cultivated land. Short-term high-intensity use of cultivated land can lead to the "deceptive" performance of cultivated land pressure. A low pressure of cultivated land was found at first, but the long-term role failed to ensure the food security with the gradual reduction of the fertility. 4) The measurement demonstrated that the current refined and improved policy was achieved in the pilot implementation of soil protection and utilization. Consequently, the pressure of arable land can be effectively relieved, even though there was a certain lag in the project. The index of cultivated land pressure was divided into four levels. Different protection suggestions were proposed to adjust the measures for the better policy benefits, according to the local conditions in the various soil pressure areas.