Soil quality evaluation in topsoil layer of black soil in Jilin Province based on minimum data set

Abstract: Soil quality refers to the comprehensive capacity of the soil, covering three aspects of maintaining productive capacity, protecting environmental quality, and promoting animal and plant health, which can sensitively reflect the dynamic changes of soil conditions and soil management. Soil quality assessment is the quantitative expression of soil intrinsic properties, which can be reflected through soil physical, chemical, and biological properties. As the main soil type in the main grain production area of the central plain of Jilin, the quality of black soil directly affects the regional ecological security and sustainable agricultural development. In this study, the typical black soil in Jilin Province was taken as the research object,1401 soil samples were collected, and 8 soil physical and chemical indexes and maize yield were determined. The Minimum Data Set (MDS) method was used to screen the evaluation indicators, the quality of the black soil was evaluated, and the suitable range of soil parameters was proposed by combining the Soil Quality Index (SQI) and the yield. The results showed that the surface soil nutrient of black soil maize growing area in Jilin Province was above the medium level, soil acidification was obvious, and the variation coefficient of soil chemical index was greater than that of the physical index. MDS for soil quality evaluation of black soil in Jilin Province consisted of soil Bulk Density (BD), Soil Organic Matter (SOM), Available Phosphorus (AP), and pH value. The filtering rate of indicators reached 50.0%, which significantly simplified the evaluation index system and eliminated the influence of information overlap among indicators on the evaluation results to the greatest extent. There were significant differences between the soil quality indexes calculated from the Total Data Set (TDS), the Important Data Set (IDS) ,and MDS. The positive correlation (0.716(R2TDS-IDS), 0.771(R2TDS-MDS) respectively) showed that the MDS was suitable to replace the TDS to evaluate the soil quality of the black soil. The SQI of the cultivated layer in the black soil maize planting area was distributed between 0.22 and 0.75, the average value was 0.53±0.08, and the coefficient of variation was 0.15, showing a high trend in the east and a low trend in the west. There was a significant correlation between the SQI and the yield (R2=0.524), which showed that the soil quality index increased firstly and then decreased with the yield, further proving that the MDS was scientific in evaluating soil quality, and the pursuit of yield should not be at the cost of soil quality. The optimum range of soil parameters for maintaining higher soil quality and yield in the topsoil layer of black soil was 1.23-1.43 g/cm3 for BD, 4.74-6.96 for pH, 33.14-35.81 g/kg for SOM, and 122.46-136.06 mg/kg for AP. BD and pH in the study area were within the appropriate range, and the improvement of SOM and AP content should be realized through straw returning, rational application of organic fertilizer, and phosphorus fertilizer. The results could provide theoretical and parameter support for the diagnosis of black soil quality, improvement of black soil fertility, and selection of suitable farmland management measures in Jilin Province.