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<br />King, P.M., 1981, Comparison of methods for measuring severity of water repellence <br />of sandy soils and assessment of some factors that affect its measurement: <br />Australian Journal of Soil Research, v. 19, p. 275-285. <br />This paper includes a comprehensive investigation and discussion of water repellency <br />measurement. The study evaluated three quick field methods of assessing water repellency <br />in sandy soils, including an ethanol drop test (modifIed from Watson and Letey, 1970), a <br />water drop penetration test, and the infilttation rate of water into soil from a small ring <br />infiltrometer. The purpose of the experiments was to determine the effectiveness of these <br />tests (by comparing them against each other and to contact angle measurements derived <br />from the capillary rise technique), and to determine factors that may have an impact on <br />repellency measurements, such as soil temperature, soil abrasion (due to sieving and <br />pouring), and soil moisture. Results showed that intense sieving dramatically reduced water <br />repellency, but that the effects of light sieving were negligible. However, it was also <br />recommended that tests be conducted on lightly sieved samples, rather than on undisturbed <br />ones, because a greater variability of repellency will result from the latter (due to root <br />channels and the uneven distribution of organic matter). Furthermore, since different <br />moisture contents produced signifIcantly variable results, the author recommended that <br />samples should be air- or oven-dried prior to testing. Temperature was also found to have a <br />signifIcant effect on water repellency, especially in South Australian soils. The author <br />suggested that this temperature sensitivity may have been responsible for the decreased <br />winter infiltration rates in South Austtalian soils described by Bond (1969), rather than an <br />increase in fungal activity. <br /> <br />Krammes, J.S., and Osborn, J., 1969, Water-repellent soils and wetting agents as <br />factors influencing erosion, in DeBano, L.F., and Letey, John, eds., Water- <br />repellent soils: University of California, Riverside, May 6-10, 1968, <br />Proceedings, p. 177-187. <br />These workers hypothesized that a wetting agent treatment could reduce surface runoff and <br />erosion from areas having water-repellent soils after wildfires. The results of several plot <br />studies in Southern California generally support the hypothesis. In most case the treatment <br />signifIcantly reduced surface runoff and erosion, and in one case not only reduced total <br />debris yield but also aided in reducing dry-creep erosion. On some plots, however, the <br />treatment was beneficial only for decreasing surface runoff, and on others it showed no <br />signifIcant result. The authors concluded that the water-repellent wetting agent treatment <br />resulted in a very favorable benefit to cost ratio, although the high cost of the treatment <br />requires data on runoff and erosion to identify potential treatment areas. The authors <br />argued for selective application of wetting agents to highly erodible areas. <br /> <br />23 <br />