PERSISTENCE OF LINURON IN SASKATCHEWAN SOILS

The persistence of linuron, at rates equivalent to 2.2 kg/ha, was studied at four sites in Saskatchewan using small field plots. Following applications made in May 1972, plots were sampled regularly and the residues remaining in the 0- to 5- and 5- to 10-cm soil levels extracted and determined colorimetrically. By November 1972, between 28 and 42% of the applied linuron was recovered from plots at the four locations. Losses over winter were slight with approximately 30% of the initial herbicide treatment being recoverable from all soil types in May 1973. Linuron residues were still detectable in plots at all sites 18 mo after application. During winter persistence studies, 50–60% of the linuron applied in October 1972 was recovered from plots in May 1973, while 30% was detected in May 1974 following October 1973 treatments. In all samplings, linuron was found in the soil from the 0- to 5-cm level, with less than 5% of the initial applications being observed in the 5- to 10-cm depths, thus indicating negligible leaching under field conditions.