To investigate the effects of shrub introduction on soil moisture， C-N-P stoichiometry， and their trade-off relationships in a desert steppe， this study was conducted in the desert steppe of eastern Ningxia. The research compared sites with shrubs introduced for different durations （8， 17 and 27 years） with a site enclosed for grassland restoration for 17 years. Soil water， soil organic carbon （SOC）， total nitrogen （TN）， total phosphorus （TP） contents， and their stoichiometric ratios in the 0-100 cm soil layer were analyzed. The root mean square deviation （RMSD） was used to quantify the trade-off between soil water and nutrients. The results showed that soil water content significantly decreased with increasing shrub introduction years （P<0.05）. Soil TN showed a significant increasing trend （P<0.05）， while TP initially increased and then decreased； both were consistently higher than those in the enclosed grassland. SOC and TN exhibited a strong coupling relationship. The soil N∶P and C∶P ratios fluctuated and decreased with increasing soil depth. Trade-off analysis revealed that the mean RMSD was 0.55 in the enclosed grassland， compared to 0.39 in the sites of shrub introduction. As soil water decreased， the synergistic effect between soil water and nutrients disappeared in the 0-100 cm layer. In summary， nearly 30 years of shrub introduction improved the nutrient content in the 0~100 cm soil layer while maintaining relatively stable soil stoichiometric ratios. However， water stress might emerge as a consequence.

Desert steppe  /  Shrub introduction  /  Chemical stoichiometry  /  Soil water  /  Trade-off