Influence of salt-tolerant medicinal herbs on soil geochemistry, nutrient cycling, and microbial communities in saline-alkali ecosystems of inner Mongolia.

Soil salinization poses a major threat to global food security and ecosystem stability. Phytoremediation using salt-tolerant, economically important plants offers a sustainable strategy for restoring degraded soils. This study evaluated the remediation potential of licorice (Glycyrrhiza glabra) and sour jujube (Ziziphus jujuba) in saline-alkaline soils of Inner Mongolia, China. Field experiments compared bare land with soils planted for one and two years. Two-year plantations significantly reduced soil pH (from 9.3 to 8.5-8.8) and electrical conductivity (from 128 to 67-74 μS/cm). Soil organic matter increased from 2.8 to 3.2 g/kg in barren soils to 5.0-5.4 g/kg under jujube. Nitrate nitrogen increased to 3.1-3.7 mg/kg under licorice and 3.2-3.6 mg/kg under jujube. Soil urease levels raised from 119 mg/g in control soils to 297 to 318 mg/g, and invertase levels increased from 0.6 mg/g in control soils to 4.9 to 5.1 mg/g in jujube soils. Furthermore, the fungal community changed from a Basidiomycota-dominated soil in barren soils to an Ascomycota-rich soil in vegetated soils. Soils under two-year licorice and two-year jujube had the highest α-diversity, with over 197 OTUs and a Shannon index of 3.22. One-year licorice had 102 OTUs and a Shannon score of 2.06. In conclusion, cultivating licorice and jujube improves soil fertility and microbial diversity, providing a long-term solution for reclaiming saline-alkaline soils in Inner Mongolia, China.