Leaching of trifluralin, linuron, prometryne, and cotoran in soil columns

An understanding of the persistence of herbicides in soils is necessary in order to prevent possible injury both to crop plants being treated and to succeeding crops in the rotation.

In order to be acceptable for use, a preemergence herbicide must insure that the crop will obtain a good competitive position and must therefore remain in an active condition in the zone of weed seed germination until the crop has attained such a position. The active condition is dependent upon many variables—the herbicide's chemical stability and solubility, temperature, soil type, rainfall, and microorganism activity.

One of the major factors in herbicide inactivation is leaching. Therefore, a study was made of the leachability of N, N-di-n-propyl-2, 6-dinitro-4-trifluromethaniline (trifluralin); 3(3,4-dichlorophenyl)-1-methoxy-l-methyl urea (linuron); 2,4-bis(isopropylamino)-6-methylmercapto-striazine (prometryne); and 3-(m-trifluoromethylphenyl)-1,1- dimethylurea (cotoran) in four agriculturally important soils.