Is macroporosity controlled by complexed clay and soil organic carbon?

• DOI: 10.1016/j.geoderma.2023.116565
• Publication Date: 2023-06-26T11:00:25Z
• Authors: Aaron N. Koop; Daniel R. Hirmas; Sharon A. Billings; Li Li; Alejandro Cueva; Xi Zhang; Hang Wen; Attila Nemes; Lígia F.T. Souza; Hoori Ajami; Alejandro N. Flores; Aoesta K. Rudick; Annalise Guthrie; Lola M. Klamm; Micah Unruh; Pamela L. Sullivan
• Keywords: Soil carbon; Soil horizon; Carbon fibers

Multi-scale evidence of rapid, climate-induced soil structural changes occurring at yearly to decadal timescales is mounting. As a result, it has become increasingly important identify the properties and mechanisms controlling development maintenance structure associated macroporosity. This especially relevant since macroporosity disproportionate effects on saturated hydraulic conductivity (Ksat) which strongly influences water storage flux, thus, affecting cycle. In this study, we use decision trees piecewise linear regression assess influence climate effective porosity (EP; proxy macroporosity) in both surface subsurface horizons under varying land-use management practices. Data from 1,491 pedons (3,679 horizons) spanning five ecoregions representing bioclimate (e.g., potential vegetation) across conterminous US demonstrate that, continental scale, EP (A) (B) dependent complexed fraction total mass organic carbon (SOC) clay; combined that refer as clay (COCC). showed slight positive response COCC A but increased steeply with increasing B horizons. because smaller values reflect larger pool greater accommodate complex additions SOC promoting stronger organo-mineral bonds concomitant these contrast, conditions where all or most effectively resulting non-complexed matter contrasting ultimately mute increases COCC. horizons, indirect factors such mean annual precipitation land were predictors EP, whereas was more influential within subsoil. The EP-COCC relationship also holds its effect mitigated by interactions suggesting complex. Plowed underlying plowed layers homogenization (due disturbance reducing heterogeneity soil) well reduction magnitude rate change function compared undisturbed Our findings suggest for Ksat ecoregion scales may be an framework understanding predicting future use- properties.