Abstract
The soil residue of PCNB, which is much used in vegetable-growing districts, was measured for six months in the open soils and in the soils covered with black plastic mulch. The rates of disappearance of residues of PCNB were different under these two conditions. In the plastic mulched soil, PCNB remained at high concentration. The residual concentration both of the metabolite and the impurity of PCNB were lower than that of PCNB, and the rate of disappearance of them in the open soil was not so different from that in the plastic mulched one.