RT Journal Article
SR Electronic
T1 Native warm-season grass establishment on spotted knapweed-infested gravel mine spoils
JF Journal of Soil and Water Conservation
FD Soil and Water Conservation Society
SP 243
OP 250
VO 58
IS 5
A1 N. W. MacDonald
A1 M. T. Koetje
A1 B. J. Perry
YR 2003
UL http://www.jswconline.org/content/58/5/243.abstract
AB We studied the establishment of native warm-season grasses on gravel mine spoils infested by spotted knapweed (Centaurea maculosa), an exotic perennial that is difficult to control on droughty, infertile sites. We applied factorial combinations of sewage sludge (o and 11.9 Mg ha−1 [5.3 tons ac−1]) and herbicide (none; 2,4-D; and glyphosate) to evaluate their effects on native grass establishment and on competition between native grasses and spotted knapweed. While native grasses were successfully established with all treatment combinations, sludge application reduced their densities. Warm season grass biomass subsequently increased rapidly on both sludge and control plots. Both herbicide treatments reduced density and biomass of knapweed during the first two years of the study, but glyphosate and sludge interacted to produce increased knapweed biomass during the third year. For this reason, it may be desirable to delay application of sludge amendments until warm-season grasses are well established in herbicide-treated areas. The response of knapweed to improved soil fertility was dependent on the degree of grass competition, and where this remained high, knapweed dominance was suppressed. While warm-season grasses appeared to compete successfully with spotted knapweed, additional control measures may be required to maintain grass dominance on this and similar knapweed-infested sites.