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9 <br />believe that the primary reason for this response is because of the <br />• opportunity that forbs have to express their growth potential on <br />shallower topsoil depths that have less grass production and <br />therefore less competition (Biondini and Redente 1986, Stark and <br />Redente 1985). <br />The response of aboveground biomass to the five manipulations <br />tested showed no difference among the treatments (Figure 2). There <br />was no difference in total or lifeform biomass among the five <br />treatments. This same result was reported in 1985 (Redente and <br />Hargis 1985) after three growing seasons. Therefore, the fact that <br />differences are not present after ten years is not surprising. <br />These results confirm that disking compacted spoil prior to <br />topsoiling to a depth of 15 to 20 cm is as effective a treatment <br />• as ripping to a depth of 60 to 90 cm. <br />In addition, the application of P to the spoil material did <br />not result in an improvement in aboveground biomass. Belowground <br />biomass was estimated in 1983 (Redente and Hargis 1985) and the <br />results at that time indicated that neither ripping nor the <br />addition of P were necessary for root development into the spoil. <br />Table 4 shows the aboveground biomass response by species <br />across the four topsoil depths. Only three species displayed <br />different production patterns in response to soil depth. The most <br />productive species on the site was smooth brome (Bromus inermis) <br />and it was favored by increasing soil depth. The most productive <br />forb was ricer milkvetch (Astraaalus ricer) and it was favored by <br />shallow soils. The third species to be affected by soil depth was <br />Kentucky bluegrass (Poa pratensis) and this species was also <br />