Objective To explore the influence of environment-friendly water-retaining materials on soil moisture characteristics.

MethodsThree environment-friendly water-retaining materials, porous fiber cotton, biochar and carbon cotton, were selected and compared with three traditional water-retaining materials, sodium polyacrylate, acrylamide-potassium acrylate and potassium polyacrylate. Sandy soil was taken as the matrix and mixed with various water-retaining materials at different mass ratios, and CK. By the method of water control experiment, the dynamic curves of soil moisture and soil water characteristic of each water-retaining material were measured, respectively. And the influence of water-retaining materials on soil water characteristics was analyzed.

ResultsThe environment-friendly water-retaining materials could reduce soil bulk density and increase soil porosity and water holding capacity. Among them, 10% carbon cotton in soil had a significant effect on the water holding parameters. Under the condition of natural drought, all water-retaining materials could restrain soil water evaporation more effectively than CK. During 40 days, 10% carbon cotton retained the most moisture throughout the water loss process. After 40 days of drought stress, the water content of 10% cotton was 3.37% higher than that of CK group. All of the six water-retaining materials could increase the soil effective water content. The soil effective water content in the material T₃ had the largest, followed by N, H, T₂, S₃, S₂, D₃, K, D₂, S₁, T₁, D₁, CKof which 10% cotton treated soil effective water content was the most.

Conclusion Through the comprehensive evaluation of principal component analysis and membership function method, 10% carbon cotton has the best water retention effect among environment-friendly water retention materials.