Agriculture is shifting towards a more sustainable paradigm, concomitantly, prebiotics have proven to benefit plant’s growth. In this study, we investigate to what extent two commercial prebiotics K1® and NUTRIGEO L®, affects soil’s fertility parameters, 10 weeks after product’s application. An agricultural soil was mixed with organic wheat straw (2% w/v) and cultivated in a greenhouse with Zea mays L. A previous study focused on plant growth parameters (SPAD, length, fresh and dry weights of shoots and roots), physiochemical analysis of the soil (pH, EC, CEC, CHN, organic matter and trace elements) and biological and molecular analysis (metabarcoding, glomalin and AMF). To deepen our understanding of these two prebiotics, we investigated the following parameters: soil microbial abundance, enzymatic activity, and potential metabolic activity were investigated.