Managing the pore system: Regenerating the functional pore spaces of natural soils by soil-health oriented farming systems

Transition towards soil-health sustaining crop production is at the core of climate change mitigation and adaptation efforts in agriculture. Improving soil conditions for resilience to variable and extreme weather conditions are among the main expectations of farmers implementing sustainable management practices. In this study, we evaluate whether the transition from conventional arable towards soil-health oriented farming systems restores soil pore characteristics towards non-arable natural soils and identify factors predominantly shaping different pore domains. Pore size distributions (PSD) at 20 sites with diverse soil types from adjacent fields of (1) standard arable, (2) soil health-oriented pioneer farming and (3) non-arable natural reference soils were measured. Based on parametric PSD descriptors, management-responsive functional pore classes and the role of textural, biochemical and structural drivers in different pore domains were analysed by a novel data-driven evaluation method. Parametric descriptors indicate an evolution from non-disturbed natural to intensively disturbed standard arable soils towards larger structural pores within a less heterogeneous structural domain. These shifts go along with less medium-sized storage pores, which overall was the most management sensitive pore fraction. Our novel data-driven approach confirmed a partial regeneration of natural pore characteristics with soil-health oriented practices. The most responsive pore domain was found in the range of similar to 0.3-0.5 mu m. The SOC-to-clay ratio was the predominant driver for structural porosity in both pioneer arable and natural reference soils. On the contrary, soil texture exerted the main control on the PSD pattern over the entire range of pore classes for standard farming systems. Overall, our study demonstrated that soil-health oriented pioneer farmers could effectively advance in managing functionally relevant pore domains for climate change resilience by promoting biological agents of structure formation.