Soil is alive – how does soil biota influence soil mechanical properties? A perspective review

There is a growing need for sustainable ground improvement, stabilization and remediation, as well as ways to maintain infrastructure. This is resulting in a rise of nature-based solutions, bio-based ground improvement techniques, bio-inspired methods, a “build-with-nature” approach. Shallow soil layers have historically been disregarded by geotechnical engineers due to unwanted characteristics, an overall lack of familiarity with the evolution of its properties in time, and/or theoretical framework for interpretation. Recent research in unsaturated soil mechanics, the characterization of organic soils, and understanding of organic matter transformation processes has improved understanding and modelling capabilities of shallow soil layers. However, soil biota (bacteria, fungi, algae, protists, soil fauna and plants) must also be considered. In this perspective, we summarize the effects of soil biota presence and activity on soil mechanical and hydraulic properties, explore their underlying mechanisms, and discuss how they can be utilized in implementing bio-based solutions. Additionally, we examine the applications and limitations of these bio-based solutions.