Impact on soil chemistry of Calyptocarpus vialis Less., (Straggler daisy), Chromolaena odorata (L.) King and Robinson (siam weed) and Parthenium hysterophorus L. (congress weed) invaded and uninvaded sites were studied during 2014-2015 in selected sites of GKVK, Bengaluru and Mysore district of Karnataka (India). Two soil cores (5 and 10 cm depth, litter discarded) were collected and subjected for analysis of pH, OC, available P K, Zn, Cu, Fe and Mn content. In C. vialis, siam weed and congress grass infested sites at surface soil (5 cm depth) and subsoil layer (10 cm depth) pH, C, P and K were less when compared to the uninvaded sites. Soil ions Zn, Cu, Fe and Mn in C. vialis and C. odorata invaded sites were more at 5 and 10 cm depth. Whereas in P. hysterophorus invaded soil, Cu, Fe ions were less at 5 and 10 cm depth and Zn was more at 5 cm and less at 10 cm depth. Mn ion was less at 5 and more at 10 cm depth. Phosphorus was less available at surface layer and more at subsoil layer in all the three weeds infested sites. Whereas, in the uninvaded sites, there was sufficient availability of P. The same is the case for K. Since the form and availability of P and K is highly pH dependant, the low pH had affected the solubility of P and K. A high variability in response to invasion was observed. Results reflected that soil chemistry was disturbed by the presence of C. vialis, C. odorata and P. hysterophorus to some extent with regard to soil pH, C, P and K contents at 5 and 10 cm depth and micronutrients Zn, Cu, Fe and Mn were increased only in the presence of C. vialis and C. odorata.