The effects of fungicides on certain chemical and microbial properties of soils

Field application of six fungicides at twice the normal rate resulted in increases in bacterial and fungal numbers after 28 days. Members of the fungal genera Gliocladium. Penicillium and Trichoderma predominated. Fungicides when applied at the field rate decreased the concentration of NO₃^? -N in soils. while the level of exchangeable NH₄⁺ -N, K, Mn and Na were generally increased. Addition of the fungicides to soil incubated in the laboratory consistently increased exchangeable Mn and K, and occasionally increased exchangeable Cu, Na and Zn. The results are discussed in relation to the microbial changes which occur, and in relation to soil fertility.