Temporal-spatial changes in cultivated land quality in a black soil region of Northeast China

Temporal-spatial variations in cultivated land quality in a typical black soil region in Northeast China were explored with 16 evaluation indices by means of the Delphi method, with weights determined by an analytic hierarchy process based on the National Standard of Cultivated Land Quality Grade (GB/T 33469-2016). ArcGIS software was used to evaluate the quality of cultivated land in the region using the same system and the same grading standard between 2008 and 2018. The goal was to identify temporal and spatial changes in cultivated land quality in the study area during the past 10 years, and the reasons for changes in the cultivated land quality. The results showed that the quality of cultivated land in the study region was dominated by medium-and low-level land in 2008, with an average cultivated land quality grade of 5.14. In 2018, the quality of cultivated land was mainly in medium-and high-level land, with an average cultivated land quality grade of 3.92. Over the past 10 years, the quality increased by 1.22. The area of first-to fourth-grade cultivated land had increased, and the area of fifth-to tenth-grade land had decreased. Meanwhile, the cultivated land grade rose 8 levels at most, and fell 7 levels most. The area of cultivated land that increased its grade was 3.5 times that of the land that experienced a decrease in grade. The quality of cultivated land in the mid-west and northwest regions of the study area increased significantly, while the south and northeast saw more decrease. This study standardized the basis of a temporal-spatial comparison analysis of cultivated land quality in the study area and revealed temporal-spatial variation characteristics of the study area, providing direction for improving cultivated land quality and sustainably utilizing and managing black soil in the future.