Some new grand questions in soil biology and biochemistry

In this Perspective, we look into the future and outline the crucial unresolved questions that can define broad directions in soil biology and biochemistry over the next decades. Considering that most of the grand questions of Selman A. Waksman have been answered over the last 100 years, we suggest here intriguing fundamental topics of basic research linking soil life with biochemical processes and ecosystem functions necessary for system understanding. We raise the following six question groups: Which level of understanding of microbial communities do we need? What are the emerging (microbial) properties and functions of soil? Are microbial memory and legacy important for soil functions? What defines soil health: pools, fluxes or potentials? Microbial growth and death: Can we identify the state of the soil microbiome and its importance for biochemical cycles? We subdivide each of these groups into narrower questions and briefly discuss the unsolved scientific problems based on previous and recent studies. The unresolved problems are visualized with exciting examples. We hope that this Perspective will stimulate new and broader discussion, as well as provide novel ideas for future research topics in soil biology and biochemistry. • New crucial questions in soil biology and biochemistry are raised and discussed. • The five major groups of questions may help define the development of soil biology and biochemistry. • These questions challenge our understanding of microbial life, biochemistry and functioning of soil. • These questions are designed to stimulate broad discussion, encourage future studies and provide new ideas.