Submitted to: Bouyoucos Conference Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 7/2/2007
Publication Date: 8/8/2007
Publication URL: http://geography.swan.ac.uk/bouyoucos2007/bouyoucos_2007_abstracts.pdf
Citation: Lehrsch, G.A., Sojka, R.E., Reed, J.L. 2007. Can surfactants affect management of non-water repellent soils? In: Bouyoucos Conference Proceedings, April 29-May 3, 2007, Sanibel Island, Florida. p. 20. Interpretive Summary:
Technical Abstract: Surfactants affect the water relations of water repellent soils but may or may not affect those of wettable soils. We studied the effects of three surfactants, Aquatrols IrrigAid Gold®, an ethylene oxide/propylene oxide block copolymer, and an alkyl polyglycoside, along with untreated tap water as a control, on the water relations of two wettable soils, a Rad silt loam (Xeric Haplocambid) and a Latahco silt loam (Xeric Argialboll). Each soil was packed 76 mm deep at a nominal bulk density of 1.1 Mg/cubic m atop 76 mm of fine gravel in 1.2-m (W) x 1.5-m (L) x 0.2-m (D) soil boxes, with four boxes per treatment. At 46.8 L/ha, each surfactant was either sprayed onto the soil as a chemigation with the first of two simulated, tap-water irrigations or was sprayed by hand onto the packed soil prior to the first irrigation. Runoff with time and sediment loss from boxes sloped at 2.5% were then measured from a 29-mm irrigation, followed one week later by a 22-mm one, each at 88 mm/h intensity. Additional measurements included bulk density, aggregate stability, surface penetration resistance, water content, and ponded and tension infiltration at three supply potentials. Though properties often differed from one irrigation to another, they did not differ due to surfactants or interactions between the surfactants and either irrigations or sampling depths. As supply potential decreased from -20 to -60 mm water, the Rad’s hydraulic conductivity after the first irrigation decreased more sharply (p < 0.047) for hand-sprayed IrrigAid Gold than for the remaining surfactants or the control, suggesting that its effect on water flow varied depending upon the pore sizes through which flow occurred. In other words, compared to the other surfactants, IrrigAid Gold increased flow through larger pores but decreased flow through pores with diameters less than or equal to 0.5 mm in recently treated, nearly saturated wettable soils, potentially achieving the double benefit of slowing drainage and increasing plant water uptake.