Influence of four pesticide formulations on microbial processes in a New Zealand pasture soil

Abstract

Application of DDT, fensulfothion, fenitrothion, and carbofuran to a yellow-brown earth in Nelson, at the recommended field rates of 2.24 kg a.i./ha, had no significant effects on the topsoil (0–3 em) respiratory activity when measured over 30 days. Storage of the pesticidetreated and untreated soil samples at –lO°e, and the time of sampling with respect to the date of pesticide application, both had small but significant effects on soil respiratory activity. When soil pesticide concentrations were adjusted to 100 ppm (corresponding to an approximate application rate of 56 kg a.i./ha), in a laboratory experiment, fenitrothion alone significantly inhibited soil respiratory activity. At 500 ppm (280 kg a.i./ha) all pesticides except carbofuran significantly inhibited soil respiratory activity.