Impact of oily waste application on the mite community on an arable soil

A two-year study on the effects of experimentally incorporated oily industrial wastes on the community structure of soil mites was performed at an old-field site in central New York State (U.S.A.). Twenty plots were divided among five groups: three treatment groups which received different application rates of oily wastes (High, Medium, Low), a natural control group (Natural) which was left undisturbed, and a rototilled control group (Control) which was subject to physical disturbance comparable to that of treatment groups, but not waste application. Wastes were applied at three times during the study (Treatments I–III) and samples were taken monthly and extracted with a high-gradient extractor.Effects of rototilling and oily waste application varied among major mite groups and the 86 species represented. In some instances effects were immediate; in others they were either delayed (determined by population phenology characteristics) or were initially masked, as when strong rototilling effects made waste-treatment effects indistinguishable. The overall immediate impact of rototilling was a reduction in both density and diversity of all mite groups (except diversity of Mesostigmata) in the upper 5 cm of soil, without total extirpation of any species. Clear negative impacts of oily wastes were noted for all major groups except the Mesostigmata, and seemed to be striking regardless of application rate. It was recovery time, rather than initial effects, which varied with application rate; heavier applications required longer periods of recovery. Relative rankings of species were clearly altered only in the Prostigmata, and only after Treatment I, but the effect was short-lived.This study was supported by the U.S. Environmental Protection Agency, subcontracted through Cornell University, Ithaca, NY (Contract CR-809285).