Soil improvement effect of planting seven gramineous plants in saline-alkali soil in the northern Xinjiang

Desert soil salinization restricts the sustainable development of the desert oasis. In this study, we evaluated whether the plantation of seven gramineous plants in a desert oasis improved soil salinization. Echinochloa crusgalli, Avena sativa, Sorghum sudanense, S. hybrid sudangrass, Purus frumentum, S. bicolor ‘Jumbo’, and S. dochna were planted on May 10, 2021. The aboveground plants and soil samples were collected on July 14, August 3 and August 24, 2021 (60, 80, and 100 days after seed sowing, respectively) for analysis. The results revealed no significant difference in the potassium ion and sodium ion contents in the forage grass of E. crusgalli, A. sativa, Sorghum bicolor × S. sudanense, P. frumentum, and S. dochna (P > 0.05). The calcium ion content in forage grass of E. crusgalli showed an increasing trend, whereas the chloride ion content showed a decreasing trend; the contents of sulfate ions and magnesium ions of forage grass of A. sativa showed a downward trend, the potassium ion content in forage grass of S. sudanense decreased first and then increased (P < 0.05), and the chloride ion and magnesium ion contents decreased. The calcium ion content in the forage grass of S. hybrid sudangrass first decreased and then increased (P < 0.05), whereas sulfate ion content significantly decreased. The magnesium ion content of forage grass of P. frumentum was the lowest at 80 days after seed sowing (P < 0.05). The magnesium ion content of the forage grass of S. bicolor ‘Jumbo’ decreased significantly and then increased, and the calcium ion content of the forage grass of S. dochna decreased. Except for P. frumentum, the chloride ion, sodium ion, and sulfate ion content in the soil of six forage species decreased. The bicarbonate ion content in the soil of E. crusgalli, A. sativa, S. bicolor ‘Jumbo’, and Sorghum bicolor × S. sudanense increased, and that in the soil of S. dochna first increased and then decreased. There was no significant difference in the bicarbonate ion content of soil between S. sudanense and P. frumentum (P > 0.05). The order of improvement effect in the ion contents in the forage grass of seven gramineae plants was E. crusgalli > Sorghum bicolor × S. sudanense > A. sativa > S. bicolor ‘Jumbo’ > S. sudanense > P. frumentum > S. dochna. The order of improvement effect in the soil ion content was S. bicolor ‘Jumbo’ > Sorghum bicolor × S. sudanense > P. frumentum > S. dochna > E. crusgalli > A. sativa > S. sudanense. When combined, S. bicolor ‘Jumbo’ and S. hybrid sudangrass were suitable as gramineous forage for soil improvement in saline-alkali soil in the northern Xinjiang.