Tests of soil fertility following repeated applications of MCPA, tri‐allate, simazine and linuron

Abstract

Summary:The following herbicides were applied annually from 1963 to experimental plots of appropriate crops grown in monoculture: MCPA 1.7 kg ha−1, triallate 1.7 kg ha−1, simazine 1.7 kg ha−1 and linuron 0.84 kg ha−1 (applied twice per year). Before the eighth treatment in 1970, nutrient status, pH and growth in greenhouse tests of a range of plants were similar in soils from treated and control plots. There were no significant differences in yield when several test crops were grown in the field plots in 1977.In a similar experiment which ran for 6 years, the same herbicides were applied twice per year at twice the above rates on each occasion (three times a year at 1.7 kg ha−1 in the case of linuron) to uncropped plots. Three years after the last treatment, there were no differences in extractable nutrients, pH, soil structure and crop yield on treated or control plots. These results support the conclusion from the main monitoring of the experiments reported elsewhere that annual treatments with these herbicides have had no adverse affect on the soil.