Plants influence the structure and function of ecosystems through litter production and by increasing soil nutrient levels. Understanding the response of soil properties to the removal or addition of litter from different species is crucial for comprehending the sensitivity of ecosystems to environmental and management disturbances. This study examined the effects of plant and litter characteristics of two grass species, Stipa barbata (C₃) and Hyparrhenia hirta (C₄), on soil carbon and nitrogen in the rangelands of Jiroft County. Treatments including 0%, 50%, 100%, and 200% litter were applied to both H. hirta and S. barbata species, and the percentage of soil carbon and nitrogen, as well as annual species production in each litter treatment, were estimated. The results indicated significant differences between H. hirta and S. barbata in terms of litter quantity, litter carbon percentage, and plant characteristics (p < 0.05). ANOVA results revealed that litter treatments had significant effects on soil carbon and annual production for H. hirta (p < 0.01) and S. barbata (p < 0.05). Results showed a positive and significant relationship between soil carbon and plant characteristics with litter carbon and litter quantity (p < 0.01). Leaf area emerged as the most important plant characteristic related to litter production. The Structural Equation Modeling (SEM) analysis demonstrated that the plant characteristics of grass species had a more substantial direct effect on soil properties than did the litter quantity and quality (p < 0.01). These findings highlight the importance of grasses in enhancing soil carbon storage in semi-arid ecosystems. The H. hirta species, due to its plant characteristics, demonstrated superior performance compared to S. barbata in terms of litter production and soil carbon enhancement. This characteristic should be considered in rangeland management strategies aimed at improving ecosystem services, particularly carbon sequestration and climate change mitigation efforts.