An innovative self-propelled machine for soil disinfection using steam and chemicals in an exothermic reaction

An innovative self-propelled machine for soil disinfection was developed using steam and chemicals in an exothermic reaction. The machine and the research carried out to define the mechanical, operative, and thermodynamic aspects of soil disinfection are described. Two activating compounds (CaO and KOH), distributed at different application rates (from 1000 to 4000 kg ha−1), were tested along with tests on the use of plastic mulching during the steam treatment. Various configurations for steam injection bars and the injection systems were tested.Working time and fuel consumption were low in comparison with other physical soil disinfection systems. Soil heating was enhanced by the addition of exothermic compounds. The use of different activating compounds at different application rates gave different results. The use of CaO at the highest application rate, together with the adoption of soil mulching with a plastic film, gave the best results in terms of soil temperature values and soil heat persistence. The temperature values reached at the various depths of soil were influenced by the different types of steam injection used during the tests. The results showed different steam injection systems could be used for treatments at different depths for different biological targets.

► Higher soil heating was achieved using exothermic compounds (CaO or KOH) than steam alone.
► Best temperature results achieved with high rates of CaO and soil mulching with plastic film.
► Optimisation of steam application at different depths thanks to the new injection systems.
► Different steam injection systems can be used depending on the target.