Soil quality assessment of Albic soils with different productivities for eastern China

Albic soil is a typical low-yielding soil in eastern China and increasing its productivity is crucial to national food security. However, research data on soil quality, which is essential to improving soil fertility and crop yield, have been limited for these Albic soils. The objectives of this paper were to: (i) establish a minimum data set (MDS) for Albic soil quality, (ii) evaluate soil quality status using a soil quality index (SQI), and (iii) determine the factors liming the crop yield. Based on the mean annual crop yield, Albic soil was divided into three classes with high (HPAS), medium (MPAS), and low (LPAS) productivity. Eighty-three soil samples were collected and analyzed for 26 soil physical, chemical, and biological properties. Principal component analysis (PCA) was conducted with 18 variables having significant differences between HPAS, MPAS, and LPAS. Based on the PCA results, an MDS was established with soil organic matter (SOM), total nitrogen (TN), pH, dehydrogenase, and arbuscular mycorrhizal fungi. The SQI was calculated using the Integrated Quality Index equation, and HPAS, MPAS and LPAS received mean SQI scores of 0.76, 0.62, and 0.50, respectively. The clear discrepancy of SQI scores suggested that there was a large potential of increasing crop yield for MPAS, and especially for LPAS. The significant correlation between the SQI and crop yield indicated the index had high biological significance for Albic soils. Overall, HPAS was characterized by low bulk density, high levels of pH, SOM, TN, enzymatic activities, and microbial activities, whereas LPAS showed conversely. Lower status of pH, SOM, and TN were considered as the major constraints limiting crop productivity for LPAS compared with HPAS. Additionally, our results also showed that all the studied soil samples were rich in available P, Si, and Zn, but deficient for available K. Managers in our study area should pay more attention to the LPAS and particularly to the any special limiting factor.