Sustainable method of soil improvement called Microbial Induced Calcite Precipitation (MICP) has received significant interest recently. In this technique, the behaviours of bio-treated soil are controlled by the amount of calcite content (CC) produced. Various methods have been used in the literature to determine the CC in soil using injection technique. The quantity of calcite precipitation is affected by the mode of application of microbes used and this effect hasn't been studied extensively. There is no preferred mode of application only the most commonly used method documented. In this paper, the CC of lateritic soil bio-treated at stepped Brevibacillus brevis (B. brevis) suspension density (SD) and cementation reagent (CR) concentration using three mode of treatment (i.e. mixing, injection and spraying method) and mix ratio (i.e., 25B–75C, 50B–50C and 75B–25C) were determined. The B. brevis SD and CR used to trigger the MICP process are based on McFarland Standards. Based on this result, the mixing mode produced the best result then injection mode and the least result was for the spraying mode of treatment. The highest CC values of 12, 8.72 and 6.4 % were recorded at 24E8 cells/ml - 1M using mixing, injection and spraying mode of treatment respectively. The recorded CC values based on the mode of treatment were in the order mixing > injection > spraying method of application respectively.
Abubakar et al. (2026) studied this question.