Preferential Flow in Vertisolic Soils with and without Organic Amendments

Core Ideas Matrix flow and macropore flow interact in Vertisols via lateral infiltration. Maximum water infiltration depths are greater in Vertisols with hog manure. Manure does not affect the mobilization of old soil water via macropore flow. Preferential flow has different agronomic and environmental effects in various soils. The objectives of this study were (i) to quantify matrix and preferential flow and (ii) to assess the effect of organic amendments on flow dynamics in agricultural Vertisols. Dye tracing and isotopic analysis were used to infer soil water infiltration and mixing on two plots: one treatment (with liquid hog manure) and one control. Results showed infiltration depths reaching 64 cm for the treatment plot and 45 cm for the control. For both plots, matrix flow was only observed in the top 10 cm, whereas preferential flow extended beyond the tillage depth. Dye traces provided evidence of lateral infiltration across macropore–matrix boundaries, while post‐experiment soil water averaged δ 2 H = −15.1‰ and δ 18 O = −118.9‰, hinting at old water mobilization via macropore flow. The potential impacts of these results on chemical transport should be validated across different soils and environmental conditions.