Field trial on use of soybean crude extract for carbonate precipitation and wind erosion control of sandy soil

大豆粗提脲酶诱导碳酸钙沉积抑制风沙土风蚀的现场试验

Wind erosion is a major cause of land desertification and sandstorm formation in arid and semi-arid areas.The objective of this study was to evaluate the potential of soybeans crude extract induced calcium carbonate precipitation(SICP)on reducing wind erosion risk of sandy soil.Field tests were carried out in Ulan Buh Desert,Ningxia Hui Autonomous Region,China.Results showed that the SICP method could significantly enhance the surface strength and wind erosion resistance of the topsoil.The optimal cementation solution(urea-CaCl2)concentration and spraying volume,according to experiments conducted on sandy land,were 0.2 mol/L and 4 L/m^2,respectively.Under this condition,the CaCO3 content was approximately 0.45%,the surface strength of sandy soil could reach 306.2 kPa,and the depth of wind erosion was approximately zero,after 30 d completion of SICP treatment.Soil surface strength declined with the increase of time,and long-term sand fixation effects of SICP treatment varied depending on topography.Whereas wind erosion in the top area of the windward slope was remarkable,sandy soils on the bottom area of the windward slope still maintained a relatively high level of surface strength and a low degree of wind erosion 12 month after SICP treatment.Scanning electron microscopy(SEM)tests with energy dispersive X-ray(EDX)confirmed the precipitation of CaCO3 and its bridge effect.These findings suggested that the SICP method is a promising candidate to protect sandy soil from wind erosion in desert areas.

风蚀作用是干旱、半干旱地区土地荒漠化和沙尘暴形成的主要原因。本文通过现场试验研究用大豆粗提脲酶诱导碳酸钙沉积法抑制风沙土风蚀的可行性。试验场地位于中国宁夏回族自治区乌兰布和沙漠地区。结果表明,该方法能够显著提高风沙土的表面强度和抗风蚀能力。适合当地的最优胶结液(尿素-氯化钙溶液)浓度为0.2 mol/L,最优喷洒量为4 L/m^2。在上述用量下,大豆粗提脲酶诱导碳酸钙沉积法处理30 d后风沙土表层碳酸钙含量为0.45%,表面强度达306.2 kPa,风蚀深度几乎为零。风沙土表面强度随时间的延长而下降,且其长期固沙效果与地形有关。大豆粗提脲酶诱导碳酸钙沉积法处理12个月后,沙丘迎风面底部和沙地风蚀程度显著降低且仍能保持较高的表面强度,而沙丘迎风面顶部风蚀较为明显。扫描电子显微镜和X射线能谱仪测试结果证实了碳酸钙晶体的形成及其桥接效应。结果表明,大豆粗提脲酶诱导碳酸钙沉积法能够有效降低风沙土的可蚀性且具有良好的耐久性,是沙漠地区抑制风沙土风蚀的候选方案。