The Association of Sorghum Growth and Physiology with Soil Carbon Sink Source Captivity in Saline Soil

The vast expanse of saline-alkali land in China represents a significant reserve of land resources for agricultural development. Therefore, it is essential to explore the saline-alkali tolerance of crops, the benefits of saline-alkali soil improvement, and their carbon sequestration potential. This study utilized the sorghum variety Jinliang 211 as the experimental material, conducting trials in saline-alkali woodland. A control and four different treatments combining organic fertilizers and soil amendments were established to investigate the effects of these mixtures on sorghum growth, antioxidant enzyme activity, soil improvement, and carbon sequestration characteristics. The results indicated that the combined application of organic fertilizer and rice husk biochar could enhance the salt tolerance of Jinliang 211, improve soil quality, and increase soil carbon sequestration capacity. Among the measured plant indicators, the T2 treatment (combined application of organic fertilizer and rice husk biochar) resulted in the highest dry matter accumulation, which was 68.4% higher than the control. Concurrently, the activities of antioxidant enzymes such as SOD, POD, and CAT significantly increased during the jointing stage post-treatment, with the highest enzyme activities observed in the T2 treatment. Regarding soil indicators, the soil organic carbon content initially increased and then decreased, with the T2 treatment showing the highest soil organic carbon content, 9.8% higher than the control. The soil pH initially decreased and then increased, with the T2 treatment exhibiting the lowest soil pH, 5.6% lower than the control. Importantly, the T2 treatment demonstrated the most pronounced “net carbon sink” characteristics in the soil. In summary, the T2 mixed treatment performed the best in enhancing sorghum antioxidant enzyme activity, increasing dry matter accumulation, and strengthening the carbon sequestration characteristics of saline-alkali soil.