Abstract:
Abstract: Desertification is a global environmental problem, bringing considerable economic, social and environmental problems to the local residents. A sand-fixing agent, Artemisia sphaerocephala Krasch. gum (ASKG), was introduced in this study to effectively control wind erosion. The ASKG was extracted from seed coat of perennial semi-shrub of Artemisia sphaerocephala Krasch. and mainly composed of glucose, galactose, mannose, rhamnose, arabinose and xylose. In order to understand the effect of ASKG on sand fixation, an experiment by spraying different concentrations (0,0.02%,0.05%,0.10%,0.20% and 0.50%) of ASKG on the sand surface was carried out. The crusts thickness, compressive strength, resistance to wind erosion, aggregate water stability, permeability and water retention and the effects of ASKG on plant seed germination and seedling growth were tested. When the ASKG was applied on the sand surface, the crust was formed in surface layer. The sand specimens treated with 0.02%、0.05%、0.10%、0.20% and 0.50% ASKG had produced the crusts with thickness being approximately 1.06, 1.31, 2.24, 2.95, and 4.30 mm and the compressive strength being around 0.10, 0.16, 0.20, 0.38, and 0.72 MPa, respectively. It indicated that the ASKG could remarkably increase the crusts thickness and compressive strength. The ability of anti-erosion was improved greatly with increasing concentration of ASKG. The sand specimens could withstand a strong wind of 20 m/s without wind erosion when the concentration was more than 0.10%. The mass fraction of micro-aggregates decreased and that of large aggregates increased because the sand specimens bonded together under the influence of ASKG. With the concentration of ASKG increased from 0 to 0.50%, the mean weight diameter of soil aggregates ranged from 0.21 to 0.52 mm in fast wetting, 0.20 to 0.73 mm in slow wetting, and 0.20 to 0.51 mm in wetting stirring, respectively. It suggested that the ASKG could notably enhance the soil aggregate water stability. The initial infiltration rate and steady infiltration rate of sand specimens treated with ASKG were 5.78-5.98 mm/min and 4.51-4.77 mm/min, respectively, and there was no significant (P>0.05) difference compared with no ASKG adding treatment with 6.13 and 4.72 mm/min, respectively. The ASKG had excellent water absorption and retention, and could promote the seed germination and seedling growth of the two pioneer sand-fixing plants (Corispermum puberulum and Artemisia sphaerocephala Krasch.). In addition, spraying ASKG on sand by the amount of 3 L/m2, the cost was 0.10-0.45 RMB per square meter. If the expense of labor was taken into consideration, the cost could be controlled to about 0.40-0.90 RMB per square meter. The results indicated that the ASKG as a kind of sand-fixing agent has the characteristics of better sand-fixing, lower cost, and environment-friendly, and can be used to desertification control with vegetation. The effect was optimal with the concentration of 0.20%. This study provides valuable information for ASKG sand-fixation application.