Effect of Long-Term Application of a Fungicide, Chlorothalonil (TPN) on Upland Ecosystem

概要

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Chlorothalonil (TPN) was applied singly or combined with γ-HCH (γ-BHC lindane) and/or compost (TPN plot, TPN+BHC plot, TPN+BHC+compost plot) each year at the ppm rate for more than 10 years to the plow layer of a long-term experimental field. In the initial period, the rate of TPN-disappearance from the plow layer in all the plots was high and it increased year by year as anticipated. In the latter period, however, the rate decreased in the TPN and TPN+BHC plots but remained high in the TPN+BCH+compost plot. In this latter period, microbial decomposition in the TPN and TPN+BHC plots appeared to be strongly suppressed and a large part of the added TPN was leached down to the subsurface horizons. This tendency was more pronounced in the TPN plot than in the TPN+BHC plot. Growth of weeds was less active and species composition was less varied in the TPN and TPN+BHC plots than in the other plots, presumably due to the smaller amount of available soil nitrogen in the TPN and TPN+BHC plots than in the other plots. Possible reasons for the suppressed decomposition of TPN and for the reduced pool of available soil nitrogen as caused by long term repeated application of TPN are discussed in relation to the role of compost.
社団法人日本土壌肥料学会の論文