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<br />Ma'shum, Mansur, Tate, M.E., Jonl~s, G.P., and Oades, J.M., '1988, Extraction and <br />characterization of watet-repellent materials from Aust 'alian soils: Journal of <br />Soil Science, v. 39, p. 99-110. <br />Rese.archers used organic solvent sys':ems to extract hydrophobi,: organic materials from <br />Australian soils. Organic materials extracted with a mixture of isc propanol/ ammonia were <br />shown to be long chain polymethylene waxes. The extractic ns indicated that water <br />repellency was not covalently linked to the surface of sand grains. This report includes <br />technical detail on structures and types of compounds in hydrophobic orgarLic materials. It <br />is useful if one is interested in bondin,~; and the chemical makeup of these compounds, or in <br />methods of extraction from soill;. <br /> <br />Ma'shum, Mansur, Oades, J.M., and Tate, M.E., 1989, The us'~ of dispf:rsible clays to <br />reduce water-repl:llency ,of sandy soils: Australian Jour tlal of Soil Research, <br />vol. 27, p. 797-806. <br />The work presented in this paper deals with the role of surface area in determining water- <br />repellency in soils, and the effects if intermixing small amounts of fi nely particulate materials, <br />including clays, upon the water repellency. Water-repellency induc, d by organic compounds <br />such as cetyl alcohol on acid-washed sand is a function of both the concentration of the <br />hydrophobic materials and the surface area of the sand. Sands \lith low surface area are <br />easily rendered hydrophobic. 1be admixture of dispersible clays ;vith water-repellent soils <br />was found to be particularly eft~c1:ive .in alleviating water-repellenc,'. The ability of clays to <br />disperse and thus spread over tlle hydrophobic surfaces of the san d grains was found to be <br />important. This ability is related to both their sodicity and particle shape, which is primarily <br />determined by mineralogy. Becam,e of their microstructures, kaolinite and illite are shown to <br />be more effective in decreasing hydrophobicity than montrnorilloni :e. <br /> <br />McGhie, D.A., 1980, The contribution of the mallet hill surfacl to runoff and erosion <br />in the Narrogin region OfWf:stern Australia: Australia!lJournal of Soil <br />Research, v. 18, p. 299-30.7. <br />Runoff and erosion were compared among fIve different land clasl es in the Great Southern <br />area of Western Australia. The re~ults showed that the mallet hill s'rrface (an Australian land <br />class) yielded the highest runoff. 1bis characteristic was attrihuted to several factors, <br />including water repellency and a "heavier textured" (higher clay cotltent) soil. Forested and <br />harvested areas of the mallet hills land class exhibited the most severe water repellency <br />(persistent even at 10-15 cm depth), which was related to comminuted surface litter in the <br />soil. A decrease in repelle.ncy with tirne (in cleared areas) was attlibuted to the removal of <br />topsoil, rather than weathering of mganic matter. Researchers also noted, however, that the <br />effect of water repellency on mnoff in forested areas of mallet r ills was mitigated by the <br />presence of surface litter. <br /> <br />26 <br />