Feldspathic sandstone as an emerging soil stabilizer for aeolian sand in the Mu Us Sandy Land: insights into particle size distribution

Stabilization of aeolian sand is essential for achieving desertification control, soil and water conservation, and agricultural development in sandy lands. Feldspathic sandstone is a soft clay rock widely found in the Mu Us Sandy Land. The purpose of this study was to ascertain the mechanism for aeolian sand stabilization with feldspathic sandstone from the perspective of particle size distribution. Feldspathic sandstone was added to aeolian sand at different ratios (<i>m</i> _f:<i>m</i> _s = 1:0, 1:1, 1:2, 1:5, and 0:1, where <i>m</i> _f is the mass of feldspathic sandstone and <i>m</i> _s is the mass of aeolian sand). The results showed that the soil texture was modified upon addition of feldspathic sandstone. The content of particles <0.05 mm increased with increasing addition ratio of feldspathic sandstone, in contrast to the downward trend observed for particles >0.05 mm. Consequently, the soil texture changed from sand to sandy loam, then loam, and finally silty loam. The addition of feldspathic sandstone ameliorated aeolian sand, resulting in a broader particle size distribution and lower particle size uniformity. Continuously well-graded soil was obtained at <i>m</i> _f:<i>m</i> _s = 1:5 (coefficient of uniformity: 54.71; coefficient of curvature: 2.54) or 1:2 (coefficient of uniformity: 76.21; coefficient of curvature: 1.12). While the addition of feldspathic sandstone solved the problem of single particle size distribution in aeolian sand, the presence of aeolian sand prevented soil compaction caused by the high clay content of feldspathic sandstone. Findings of this study indicate that the addition of feldspathic sandstone to aeolian sand leads to the mixing of various sized particles and continuous gradation of the soil. Although a higher addition ratio of feldspathic sandstone is more favorable for soil texture improvement, <i>m</i> _f:<i>m</i> _s = 1:5 is recommended for practical application in terms of particle gradation and cost effectiveness.