Effect of steam and exothermic substances (KOH and CaO) on lettuce and strawberry production: two years of experimentation.

摘要

Addition to the soil of substances causing an exothermic reaction to make disinfection by steam more efficient may have effects on crops due to the resulting changes of soil chemical characteristics. The present paper describes effects on lettuce and strawberry of soil disinfection by steam combined with increasing doses of KOH or CaO (0, 1000, 2000, 4000 and 8000 kg ha-1) for two consecutive years (2002 and 2003) at the University of Pisa, Italy. KOH and CaO can be used in association with steam for soil disinfection in vegetable crops without production risks, provided that the applied dose does not exceed 4000 kg ha-1, with regard to soils comparable to that used in the trials (sandy loam texture, alkaline pH, sufficient amount of organic matter and nutrients). In fact, relevant reductions of yield were observed only with the 8000 kg ha-1 dose, that caused more evident increases in soil pH and electric conductivity. To exclude problems due to repeated applications and to reduce the cost of the treatment, doses of 1000-2000 kg ha-1 are recommended.