Background To address the issues of water shortage and high irrigation costs in dryland high-standard farmland in the Ordos region, this study used three environmentally friendly plant-based sand-fixing agents as materials and conducted multi-dosage treatments to explore their impact on the local soil water retention performance and water-saving economic benefits. The aim is to screen the optimal type and dosage of sand-fixing agents suitable for the region and provide support for the efficient utilization of farmland water.

Methods In this study, an indoor simulated evaporation test was conducted on soil samples treated with three plant-based sand-fixing agents (Artemisia desertorum sand-fixing agent, Linum usitatissimum sand-fixing agent, and Robinia pseudoacacia sand-fixing agent) and six different doses (0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 g/m²) on the surface. The same amount of pure water was sprayed as the control (CK). By comparing the cumulative evaporation volume of different treatments after continuous evaporation for 30 d and through the fitting analysis of the Black and Rose evaporation models, the water retention effect of plant-based sand-fixing agents was further explored and their water-saving economic benefits were calculated.

Results 1) After continuous evaporation of three plant-based sand-fixing agents for 30 d, the cumulative evaporation of each treatment was significantly lower than that of CK. The L. usitatissimum sand-fixing agent had the most significant effect in inhibiting water evaporation, followed by the R. pseudoacacia sand-fixing agent, and the A. desertorum sand-fixing agent was the weakest. The effects of the three sand-fixing agents on the soil evaporation rate of sandy farmland all show that the water retention effect is better when the application concentration was 2.0 to 4.0 g/m². 2) The R² of the Black evaporation model ranged from 0.951 to 0.999, while that of the Rose evaporation model ranged from 0.917 to 0.997. The Black model more truly reflected the variation law of cumulative soil evaporation over time. The model fitting results showed that the effect was better when the concentration of the sand-fixing agent is 1.0−4.0 g/m², and R² was all greater than 0.990. 3) The water-saving economic benefits of each treatment were as follows: L. usitatissimum sand-fixing agent (10 513 yuan/(10 000 mu·a)) > A. desertorum sand-fixing agent (2 753 Yuan/(10 000 mu·a)) ≈ R. pseudoacacia sand-fixing agent (27 250 Yuan/(10 000 mu·a), 1 mu = 0.006 67 hm²).

Conclusions Therefore, the application rate of 3.0 g/m² of L. usitatissimum sand-fixing agent can effectively reduce irrigation costs, enhance the water retention capacity and water-saving economic benefits of high-standard farmland, and is suitable for promotion and application in the construction of dryland sandy high-standard farmland in northwest China.