• Core Ideas
• Xanthan as an eco‐friendly polymer can prevent the movement of sand dunes.
• The study of how xanthan penetrates in sandy soil is important in sand dune fixation.
• Gradient motion and penetration time of xanthan are essential in biomulch operation.

Studying the infiltration of water–xanthan solutions into sandy soil to prevent the movements of sand dunes is important for predicting xanthan mobility, understanding xanthan conditioning depth, and evaluating the physicochemical effects on the behavior of xanthan in sandy soil. This paper provides insights into laboratory tests conducted to determine the effects of xanthan concentration, temperature, salt, and pH on the infiltration of xanthan solutions in sandy soil. The infiltration experiments used a series of batch vertical sand columns. Xanthan solution, which had been treated under different conditions, was poured on the surface of the experimental soil, and infiltration of xanthan was measured. Infiltration of xanthan decreased with increasing xanthan concentration. Based on the test results, an optimum concentration of 0.25% (w/v) was selected. The infiltration of xanthan solution in sandy soil increased after an increase of temperature from 25 to 45°C; however, a further increase in temperature to 60°C had no significant effect. The addition of KCl and CaCl₂ at concentrations of 100, 500, and 1000 mmol L^–1 increased infiltration significantly, but increasing the salt concentration from 100 to 1000 mmol L^–1 had no significant effect. Moreover, the type of salt (monovalent or divalent) over the selected concentration range had no significant effect. The results showed that the pH of xanthan solution (5, 7, and 9) had no significant effect on infiltration. The Kostiakov equation fit the experimental infiltration data well for all cumulative infiltration curves. Understanding the effect of xanthan concentration and physicochemical parameters on infiltration of xanthan in sandy soil is helpful in sand dune stabilization.