Intensified soil solarization with closed greenhouses: Numerical and experimental studies

Soil solarization (heating by mulching a wet soil with transparent polyethylene sheets) for controlling soil-borne pests, has been used in regions with high temperatures and intense solar radiation. In cooler periods or regions, however, this method is not effective in the open field, but can be envisaged in closed greenhouses. In the present study, we developed a numerical one-dimensional model to predict the soil temperature regime in closed non-mulched and mulched greenhouses under various meteorological conditions. The model consists of six layers: cover, mulch, soil and three air layers (external, enclosed between soil and mulch, and enclosed between mulch and cover). Soil hydraulic and thermal characteristics, greenhouse cover and mulch photometric properties, and diurnal cycles of the environmental conditions are required for the simulations. The model was experimentally verified and applied to glass- and polyethylene-covered greenhouses, examining the influence of greenhouse covering material on heating of the mulched soil. Mulching the soil inside closed glasshouses increased the effectiveness of solarization over mulched soil in the open field or in closed polyethylene greenhouses.