Soil disinfestation by steam is an agricultural technique that is nowadays attracting growing interest for its low ecological impact and could therefore become a viable alternative to methyl bromide, that will soon banned. The current main limitation of this treatment is due to the cost of the fuel used to generate the steam. In this paper, we present a control strategy that allows to minimize fuel consumption by optimizing the time of steam soil exposure. The effectiveness of the proposed techniques has been tested using real data collected from experiments performed in a farm in the Liguria Italian region.