Enzyme Induced Carbonate Precipitation (EICP) technology using self-extracted soybean urease is an emerging soil improvement technology in geotechnical engineering. This technology has many advantages, such as economic, green and environmentally friendly. However, the high turbidity of the self-extracted soybean urease solution can cause bioclogging during the biogrouting process, resulting in poor biocementation along the depth. In this study, a solvent containing alum was used for the extraction of soybean urease solution to reduce its turbidity. A series of macroscopic and microscopic experiments and tests were conducted to investigate the effects of alum content on turbidity and biocementation of the extracted soybean urease solution. The results indicate that the use of the alum-containing solvent can effectively reduce the turbidity of the self-extracted soybean urease solution. However, excessive amounts of alum (e.g., more than 3.0 g/L for 100 g/L of soybean powder) may cause the urease activity of the soybean urease solution to decrease or drop to zero. The use of soybean urease solution with low turbidity is beneficial to improve the distribution uniformity of precipitated calcium carbonate along the depth, thereby enhancing the strength of the biocemented sand, while having no apparent effect on the morphology and crystallinity of the precipitated calcium carbonate crystal.