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 relationship =~ = KC" 
on a log x log scale. The slope of the line then represents "n"'. From plots 
of this type, the total amount of herbicide to be applied may be calculated. 
Calculations show that the concentration of herbicide to be applied, 
expressed in kg/ha, is roughly equal to 1/10 the soil concentration — 
at the 1 ppm level. This rule of thumb applies to soils having a high 
moisture level (531, 532). 
_ y chemical 
~ g soil 
concentration of chemical fixed on soil 
Als 
pus Y chemi ¢al 
ml water 
concentration of chemical in solution 
nw 
ll 
constant 
5 
ul 
slope 
486 
