Natural & managed soil structure: on the fragile scaffolding for soil functioning

Abstract:

The structure of natural soils is a product of complex interactions among biological agents, climate and soil type that promote aggregation and biopore formation. Soil structure management in arable lands requires mechanical fragmentation to improve seedbed, control weeds and bury plant residue. Despite difficulties in defining soil structure, its importance is clearly evidenced by loss of functions following disruption of natural soil structure (i.e., compaction, fire) or yield losses in certain transitions to no till (for arable land). Advances in understanding this important trait require 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 massive transition to no-till since the 1960s calls to question the need for tillage. We use metanalysis of conventional and no-till to delineate regions and crops where tillage remains an important practice for high yields. Levels and trends of SOC emerge as integrative and sensitive metrics for soil structure state and attainment of equilibrium since perturbation. Soil structure state in natural and arable lands provide a basis for evidence-based decisions related to land management and ensure sustainable functioning of a fragile and central resource such as soil.