SLAKES and 3D Scans characterize management effects on soil structure in farm fields

Adoption of no-till (NT) is low in the Lower and Middle Brazos River Watershed of Texas, leaving soil vulnerable to erosion, exacerbating flooding, and contributing to high nutrient and sediment levels in surface waters. To investigate the impact of NT on soil structure and hydraulic function in the region, we measured saturated hydraulic conductivity, organic carbon, bulk density, slaking index of soil aggregates (inversely related to aggregate stability), and soil structure in farm fields under three management systems: conventional tillage (CT), NT, and perennial grass (PG). Soil structure was measured using a novel method for 3D scanning of soil surface horizons - multistripe laser triangulation. Slaking index was measured using a recently developed smartphone application. Exploratory factor analysis combined with a semi-supervised cluster analysis showed that, in general, CT and PG fields were classified into different clusters from one another. Three fields managed with NT for 21, 21, and 7 years were classified in the same cluster as PG fields, while the remaining fields (managed with NT for 21, 21, 18, and 3 years) were classified with CT fields. Organic carbon was significantly higher in NT compared to CT fields. Conventional fields had significantly lower hydraulic conductivity than PG fields and hydraulic conductivity was 1.3 cm h-1 higher in NT than CT fields. Soil structure measured from 10-30 cm depth was significantly improved in NT compared to CT. Improvements in organic carbon and soil hydraulic function are meaningful indicators of improved physical soil health that can be used to promote NT adoption. Improvements in organic carbon and soil hydraulic function also provide ecosystem services to off-site stakeholders who are impacted by erosion and sedimentation resulting from soil tillage. The two novel measurements (a metric derived from scanning of soil structure and slaking index from a smartphone application) were particularly sensitive to management system. <comment>Superscript/Subscript Available</comment