Soil factors preventing revegetation of a denuded area near an abandoned zinc smelter in Oklahoma.
Watkins & Rice (1974) concluded that the denuded area probably remained bare because of the high concentrations of cadmium and zinc combined with low pH. In the present study, calcium was found to be about twice as high in concentration in the control. Amounts of exchangeable ammonium nitrogen were about the same but the concentration of nitrate was much higher in the control. This was positively correlated with the higher counts of nitrifiers in the control plot and indicated that the nitrification rate was much reduced in the bare plot. The absence of ammonium nitrogen increase in the bare plot suggested that the ammonification rate was decreased also. Total available nitrogen was lower in the bare plot. Mean numbers of bacteria, fungi and actinomycetes were considerably higher, and activities of urease and dehydrogenase were much higher, in the control soil. Numbers of Azotobacter were zero in both plots.