Scanning electron micrographs of polyacrylamide-treated soil in irrigation furrows

Escaneando micrografías de electrones en suelos de surcos de irrigación tratados con poliacrilamido

Ross, C.W. and Sojka, R.E. and Foerster, J.A. (2003) Scanning electron micrographs of polyacrylamide-treated soil in irrigation furrows. Journal of Soil and Water Conservation. 58(5):327-331.

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Abstract

Polyacrylamide (PAM) is used at rates of i to 2 kg ha per irrigation on a half million
hectares of United States irrigated farmland to prevent 94% of irrigation-induced erosion and to
enhance infiltration by 15% to 50% on medium to fine-textured soils. The polyacrylamides used
for this application are large (12 to 15 megagrams per mole), water-soluble anion molecules
applied in the irrigation stream. Erosion prevention has been shown to result from stabilized soil
structure in the i to 5 mm veneer of surface soil that regulates infiltration, runoff, and sediment
loss on water application. We hypothesized that this could be confirmed from scanning electron
micrographs (SEMs) of PAM-treated soil. Both untreated and PAM-treated soils form surface
seals in irrigation furrows, but the stable surface structure of PAM-treated furrows is more
pervious. This is thought to result from a greater number of continuous unblocked pores at the
soil-water interface. SEMs of PAM-treated and untreated soil microstructures are presented
from thin surface samples of Portneuf silt loam, collected from furrows immediately following an
irrigation, and freeze-dried. SEMs of PAM-treated soil showed net or web-like microstructural
surface coatings about 1um thick on soil mineral particles, giving a glue-like porous appearance.
Individual strands of PAM were about 0.2 in diameter. Strands of PAM aggregated the soil by
ensnaring and bridging mineral particles while untreated soil had poorly aggregated,
unconnected particles. Thus, microstructural differences between PAM-treated and untreated
soil from irrigation furrows were consistent with erosion and infiltration results.

Item Type:	Article
NWISRL Publication Number:	1114
Subjects:	Polyacrylamide (PAM) > Water-soluble PAM (WSPAM) Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:50
Last Modified:	08 Nov 2016 15:40
Item ID:	170
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/170