InterPore2022

Agrochemical Transport in Heterogeneous Agricultural Soils

2 Jun 2022, 15:15

1h 10m

Poster Presentation (MS02) Porous Media for a Green World: Water & Agriculture Poster

Speaker

Veronica Morales (University of California, Davis)

Description

The fate and transport of contaminants associated with agricultural soils have important implications for groundwater quality and public health. Intricacies of the pore structure control how water flow is distributed and consequently how dissolved chemicals are transported in the subsurface. We hypothesize that the structural heterogeneity generated by different agricultural land management practices (ploughed vs no-till) will affect the transport behavior of agrochemicals in these soils. We test this hypothesis with data from direct numerical simulations of tomographic images of soil samples obtained from a long-term agricultural field station in the United Kingdom. The flow in each soil domain is resolved from the full Navier-Stokes equations and transport is simulated from tracking of massless particle tracers. A statistical analysis of the Lagrangian tracks is presented to compare the velocity distribution, velocity correlation length, breakthrough curve, and evolution of displacement moments that characterize each land management practice. Our findings show that for low Peclet numbers, representative of natural water infiltration, the two soil treatments have comparable transport behavior with mild anomalous characteristics. Conversely, for high Peclet numbers, representative of infiltration rates from Ag-Managed Aquifer Recharge, transport in ploughed soil is significantly more anomalous than in no-till soils. An improved understanding of the controls for contaminant transport in agricultural soils and of the predictive tools to model contaminant transport are key to helping decision makers implement more sustainable strategies in agriculture.