Soil Solarization in a Greenhouse for Controlling Fecal Contamination

Abstract

Contamination of agricultural soil by fecal pathogenic bacteria poses a potential risk of infection to humans. As a way of biosafety control, soil solarization in a closed greenhouse was examined for the efficiency on the inactivation of Escherichia coli which was inoculated into soil as a model microorganism for fecal pathogenic bacteria. Soil solarization greatly increased the soil temperature (depth of 15 cm), which reached up to 40°C within the first one week of solarization, thereafter fluctuated between 40 and 46°C in most of the solarization periods. The population of E. coli in the solarized soil decreased dramatically from 105 CFU g−1 dry soil to undetectable level (‹0.1 CFU g−1 dry soil) within one week as a result, whereas E. coli was detected even after four weeks in the non-solarized soil in an open greenhouse. Soil solarization, however, had little effect on the total direct count and total viable count of bacteria in the soil. These results indicate that soil solarization would be useful for the rapid biosafety control of soil contaminated by human pathogens via immature compost or animal feces under greenhouse environments.