Soil–Plant–Microbe Interactions Determine Soil Biological Fertility by Altering Rhizospheric Nutrient Cycling and Biocrust Formation

Understanding soil–plant–microbe inter- and intra- interactions are essential for ensuring proper soil health, quality, and soil-mediated ecosystem services (e.g., nutrient cycling) required for human–plant–animal life. Intensive and unsustainable farming practices can decrease soil microbial biodiversity, fertility, and quality leading to soil degradation, impaired nutrient cycling, and the incapability of soil to support plant growth. Under such a context, soil biological fertility can appear as a regenerative component that has the potential to harmonize and improve soil’s physical, chemical, and biological parameters. This study defines and discusses the microbiome in the rhizosphere, microbial nutrient cycling, and biological soil crusts as the major components of soil biological fertility, and explores the answers to the following questions: (i) how does the rhizosphere promote plant growth, development, and nutrient cycling through soil microorganisms (e.g., bacteria, fungi)? (ii) How can soil microorganisms regulate macronutrient cycling and facilitate biocrust formation? This review reveals that soil biological fertility is crucial for increasing crop resilience and productivity as well as sustainability in agriculture. Additionally, the reintroduction of plant growth promoting rhizobacteria, a quantitative estimation of the root exudate’s composition, identifying the spatiotemporal dynamics of potassium solubilizing bacteria and establishing biological soil crusts in agricultural lands remain the major tasks for improving soil biological fertility and the transition towards regenerative agriculture.