Characterizing flow through the soil matrix and preferential flow pathways (PFPs)
Abstract
Using liquid latex as a method to seal preferential flow pathways (PFPs), this study attempted to (1) quantify the contribution of preferential flow to overall flow at various moisture contents, and (2) characterize the effect of preferential flow on soil moisture profiles to 60 cm in depth. Field research was conducted in silty clay loam soil under a no-till corn/soybean rotation field planted to corn. Surface intake rates were measured using a simplified falling head technique under two scenarios: (1) natural soil conditions with unaltered PFPs; and (2) similar soil conditions with latex-sealed PFPs. Further analysis of the latex recovered from the sealed PFPs was conducted in order to differentiate and quantify desiccation crack volumes from biological volumes. Results indicated that the contribution of preferential flow to surface intake rates varied from approximately 34 to 99% depending on the initial moisture content and volume of PFPs present. The moisture profiles in the latex treated frames collected after 1-2 days of water redistribution generally showed uniform increases in water content per 10 cm depth layer in the surface horizon compared to the background moisture profile. Sealing the PFPs with latex simulated Darcian-like flow conditions. Crack volumes decreased with depth while biological volumes remained fairly constant with depth. Using moisture content as the sole predicator of desiccation volume resulted in a low r-squared value (0.22), which indicated that other factors, such as vegetation, field management practices, and biological activity, affected the dynamics of crack formation, evolution and volume.
Degree
M.S.
Advisors
Mohtar, Purdue University.
Subject Area
Soil sciences|Natural Resource Management|Water Resource Management
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