APPENDIX 2 
CALCULATIONS FOR 
ADSORPTION AND LEACHING OF HERBICIDES 
Adsorption 
Adsorption of a compound can be measured in a system of fixed 
soil-solution ratio and varying herbicide concentration. This may 
be plotted in terms of the empirical isothermal Freundlich relation- 
ship = = KC" on a logXlog scale. The slope of the line then rep- 
resents n. From plots of this type, the total amount of herbicide 
to be applied may be calculated. Calculations show that the con- 
centration of herbicide to be applied, expressed in kg/ha, is 
roughly equal to ide soil concentration ae the 1 ppm level. 
This rule of thumb applies to soils having a high moisture level 
(Geissbuhler et al., 1963). 
x = xc? 
m 
x Y chemical 
m- g soil = concentration of chemical fixed on soil 
y chemical 
Cc = ——— = concentration of chemical in solution 
ml water 
K = constant 
n = slope of line 
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