Soil structure in natural systems is a product of complex interactions between biological activity, climate and soil
minerals that promote aggregation and accumulation of biopores. In arable lands, the management of soil
structure often requires the mechanical fragmentation of hardened soil to improve seedbed, control weeds and
bury plant residue. Despite difficulties in defining and quantifying soil structure, its critical role is evidenced by
loss of productivity when natural structure is perturbed (e.g. compaction) and the long history of tillage in
agriculture. To overcome persistent ambiguities among scientific disciplines regarding definition and function of
soil structure, we propose a framework for distinguishing managed and natural soil structure based on their
different formation processes and functions. Natural soil structure preserves ecological order and legacy that
promotes biopore reuse, stabilizes foodwebs and protects soil organic carbon (SOC). The contribution of net
primary productivity of natural lands to soil structure forming processes makes it a useful (surrogate) metric of
soil structure. The benefits of managed soil structure for crops are quantified indirectly via comparisons with notill
farming under similar conditions. The levels and trends of SOC are useful metrics for the status of natural and
managed soil structure. The systematic consideration of soil structure state in natural and arable lands using
suitable metrics is a prerequisite for rational decisions related to land management and ensuring sustainable
functioning of a fragile and central resource such as soil.