Evaluation of the Effects of Different Cultivars of Falcataria falcata on Soil Quality

The soil microbial community influences and maintains soil quality and health. Leguminous plants are widely used in forestry due to their nitrogen-fixing ability, significantly improving soil quality. However, there are few studies on the effects of woody legumes on soil microbial communities and soil quality. Here, the composition and structure of bulk soil microbial communities associated with six cultivars of Falcataria falcata (L.) Greuter & R. Rankin were analyzed using full-length 16S rRNA sequencing. Additionally, the minimum dataset approach was employed to integrate indexes of soil microbial communities and physicochemical properties, allowing the calculation of a soil quality index to evaluate the cultivars’ soil quality. Although the growth characteristics of the six cultivars were identical, there were significant differences in physiological functions. Notably, cultivar 6 demonstrated a significant advantage over the other cultivars in its overall physiological characteristics. Compared to the control sample, all cultivars clearly improved soil quality, with cultivars 8 and 16 significantly outperforming the others. The findings indicate that the different cultivars improve soil fertility by recruiting microorganisms with specific functions. The stability of soil microbial communities is a crucial biological and ecological factor that influences and sustains soil quality and health and is a key index for the evaluation of these properties.