Investigating Spatial Distribution of Soil Quality Index and Its Impacts on Corn Yield in a Cultivated Catchment of the Chinese Mollisol Region

The Mollisol region of Northeast China is an important crop production base of China. The soil quality of this region has greatly decreased in recent decades due to unreasonable land management, which in turn has reduced crop yields. The objectives of this study were to investigate the spatial distribution of a soil quality index (SQI) and the relationship between crop yield and soil quality in a catchment of the Chinese Mollisol region. A total of 168 soil samples were collected based on a 200- by 200-m grid and 4 yr of corn (Zea mays L.) yields and 15 soil quality indicators, including physical, chemical, and biological properties, were analyzed. Principal component analysis indicated that the critical indicators for characterizing soil quality were soil organic matter, total N, sucrase activity, NH₄⁺–N, microbial biomass C, and microbial biomass N. The SQI varied from 0.147 to 0.804 with a mean value of 0.388. The spatial distribution of soil quality and corn yield showed that high values of both soil quality and corn yield were located in the north, and low values were in the south of the catchment. An empirical equation between corn yield and SQI was fitted, and cross-validation results showed that the empirical equations could be used to assess soil quality effects on corn yield with acceptable accuracy in the research area. Hence, to realize agricultural sustainability, effective soil conservation measures, such as no-till, cover crops, and retaining crop residues should be implemented in the study area instead of current cropland management measures.