Several prototypes of a machine (drawn, mounted and self-propelled) for soil disinfection by means of steam injection at different depth, after the incorporation in the soil of varying amounts of compounds (KOH, CaO, etc.), that cause an exothermic reaction, were developed and improved in five years period 1998-2003 by the Celli firm, in co-operation with the researchers of the Centro Interdipartimentale di Ricerche Agro-Ambientali “E. Avanzi” of the University of Pisa. The tested system showed a promising potential, as it was able to perform a remarkable soil heating and to control telluric pathogens and potential weed flora. To estimate this last matter a specific experiment was carried out - in controlled conditions - in spring-summer 2003 to evaluate the effects of the application of this system on seed germination of both microthermal and macrothermal weeds, with very interesting and encouraging results.