SIDE-EFFECTS OF SEQUENTIALLY-APPLIED PESTICIDES ON NONTARGET SOIL-MICROORGANISMS - FIELD EXPERIMENTS

A plant protection system consisting of 7 pesticide treatments was investigated for its side-effects on the soil microflora. Measurements of microbial activity were based upon microbial biomass. dehydrogenase activity, ammonification and nitrification. Investigations were carried out over 2 yr in a field experiment with four replications. Successive applications of the pesticides caused only slight and short-lived side-effects on the soil microflora. These usually disappeared before the next treatment was carried out. The results appeared to be significantly influenced by weather conditions. Thus. side-effects were less in 1986 despite a more rapid sequence of pesticide treatments compared to the year before. © 1990.