Abstract: Enzyme-Induced Carbonate Precipitation (EICP) has attracted increasing attention in geological and geotechnical engineering due to its environmental friendliness and potential for soil improvement. However, the poor stability of conventional urease solutions under natural conditions remains a major limitation for the large-scale application of EICP technology. To address the rapid activity decay of soybean urease at ambient temperature, this study conducted preservative screening tests and found that the addition of 1.5% sodium dehydroacetate effectively extended the storage period of soybean urease to 360 h. Subsequently, EICP solution tests and sand column cementation experiments were performed to investigate the effects of modified urease on reaction efficiency and sand solidification performance. The cementation effects of the conventional single-phase method and the low-pH single-phase method were also compared. The results show that the modified urease achieves a calcium ion conversion efficiency exceeding 90%. The average unconfined compressive strength and calcium carbonate content of the cemented sand columns reach 2027.1 kPa and 7.4%, respectively, which are higher than those of the untreated urease solution group. The low-pH single-phase method effectively delays the initiation of the reaction by approximately 3 h and may contribute to a more uniform spatial distribution of calcium carbonate precipitation. Microscopic analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD) reveal that the precipitated calcium carbonate mainly consists of calcite crystals, which extensively cover the surfaces and contact points of sand particles, thereby enhancing particle bonding strength. This study provides a reference for the storage and practical application of soybean urease in EICP-based soil improvement under field conditions.