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<br />taken within each treatment in May and August. Ashing followed weighing of dry <br />material into crucibles and was done at 450 Oc for four hours. <br /> <br />Results and Discussion <br /> <br />Examination of the data in Tables 1 through 3 clearly demonstrates that <br />only the Agropyron smithii site's wind erosion :potential was affected b:y soil <br />water status, declining markedly with increased water. The Agropyron site's <br />CTL plots lost as much as 10 times the soil debris as WET plots on the same <br />date. The magnitude declined as the season progressed although the <br />proportional difference among the treatments persisted. Correcting for mineral <br />ash content (Tables 1 and 4) alone makes the water influence even more <br />dramatic. Estimates of mineral soil loss are a:s high as 25.1 g/O.1 m2 l:>n the <br />CTL treatments, dropping to 13.6 on the SWT plots, and declining even further <br />to 3.2 on the WET plots as of May 23. <br /> <br />Neither of the sites with Bouteloua as a dominant speeies showed soil water <br />influence on soil loss at any time (Tables 2 and 3). Indeed, except for the <br />two sample periods which inunediately followed mowing (4/7 and 20/7) there was <br />no difference between mowed and unmowed treatments in the A+B+S community as <br />shown in Table 3 (paired t-test, p~0.05). An apparent, but weak, seasonal <br />trend occurred at both sites with the C4 grass, as happened to a substantial <br />degree on the exclusively C3 grass community. Soil erosion is probably of no <br />practical significance at the two sites where Bouteloua is present sinc,~ only <br />small quantities of debris were suctioned and the greatest proportion of that <br />was litter and other organic debris, not mineral soil (Table 4). <br /> <br />Comparison of soil lost from the three community types leads one to the <br />obvious conclusion that the C3 community is much more likely to los,e nutrients <br />by wind erosion than those with just C4 grass species or a mixture of types. <br />The mean (.:t 1 SE) mineral soil loss from the !&1~opyron plots (7.66 g/O. II m2 <br />.:t1.49) is in sharp contrast to the Bouteloua mean value of 0.09 .:t 0.02 and that <br />on the unmowed A+B+S plots of 0.49 .:t 0.04 and 011 mowed A+B+S plots of 0..67 .:t <br />0.07. The Agropyron smithii community's wind erosion potential is .at lE~ast an <br />order of magnitude greater than that of the mixE~d community and nearly two <br />orders of magnitude greater than that occurring on a nearly pure Bouteloua <br />gracilis stand. <br /> <br />Is the Agropyron smithii site's relatively poor ability to resist wind <br />erosion unusual or is it a trait common to many C3 grass communities? Suction <br />debris samples (n=10) were taken on August 16, 1979 from a disked Artemisia <br />~ community which had been planted to Elvmus and Bromus., both C3 grafls <br />genera, in late 1977. The means (.:t 1 SE) were i'.08 (0.97) and 8.57 (0.95) <br />g/O.1 m2. These weights were no different (paired t-test, p~0.05) than those <br />from the Agropyron smithii CTL plots of the SamE! day. However these erclsion <br />potential indications were far higher than thOSE! from either the A+lB+S or <br />Bouteloua gracilis CTL plots at that time (pairE!d t-test, p~O.Ol). <br />Incidentally, the soil of the renovated area waf~ nearly identical to th~lt of <br />the C4 community. Thus C3-dominated communities may be tentatively declared to <br /> <br />be more wind erosion prone than either mixed or nearly pure C4 grass st~Lnds. <br /> <br />63 <br /> <br />