Simazine soil movement

Finally, certain triazine herbicides can be used selectively in orchards and in some horticultural crops. In this case, selectivity is not based only on physiological differences between species, but on physical selectivity associated with the location of the herbicide and the roots of the crop and weed species in the soil. Triazine herbicides such as simazine, which has very low solubility in water, remain close to the soil surface in most mineral soils. Careful application of simazine in horticultural or fruit crops can result in the herbicide being available to control shallow-rooted weed species without harming the deeper-rooted perennial species. The success of this use is dependent not only on the relative rooting depths of the tolerant and susceptible species, but also on soil conditions and other factors that may affect herbicide fate and movement. 

Triazine herbicide soil activity, movement, and residues depend primarily on content of organic matter, and to a lesser extent, clay colloids (Nearpass 1965 Day et al, 1968 Weber et al, 1969). Soils that are low in organic matter or clay usually require lower herbicide rates, but result in more potential phytotoxicity (Lange et al, 1969a). Simazine (4.0kg/ ha) or diuron (5.0kg/ha) gave season-long weed control in soils of the Northwest (Hogue and Neilsen, 1987). 

Hance, R.J., S.J. Embling, D. Hill, I.J. Graham-Bryce, and P. Nicholls (1981). Movement of fluometuron, simazine, 36CL and 144Ce3+ in soil under field conditions Qualitative aspects. Weed Res., 21 289-297. 

Wang, Y.-S., J.-R. Duh, K.-Y. Lin, and Y.-L. Chen (1996). Movement of three s-triazine herbicides atrazine, simazine, and ametryn in subtropical soils. Bull. Environ. Contam. Toxicol., 57 743-750. 

We suggest that simazine movement in Rutland sandy loam is less than otherwise anticipated because at this soil s low pH (4.6), more of the simazine is protonated, and therefore more strongly adsorbed, than in Penticton loam (pH 7.5). 

Zalkin, F. Wilkerson, M. Oshima, R. J. Pesticide Movement to Groundwater. Vol. II. Pesticide Contamination in the Soil Profile at DBCP, EDB, Simazine and Carbofuran Application Sites" Calif. Dept. Food and Agric. Sacramento, Calif. Final Rep., EPA Grant E009155-79 1984. 

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