Parametric Analysis of Soil Temperature in a Solarization Treatment in Closed Greenhouse

Soil solarization is a method of non-chemical disease control that employs solar radiation to heat moistened soil, mulched with a plastic film, up to temperatures that are lethal for soil-borne pathogens. The use of this technique in closed greenhouse has allowed its spreading in that areas characterized by temperate climate, such as the Mediterranean Basin. However, the optimization of the technique needs the knowledge of the physical processes inside the soil-mulch-greenhouse system that determine the thermal regimes in the soil. Thus, it is possible to build mathematical models able to predict the effects determined by the variation of each parameter on soil temperature without a specific field trial. In this paper, a parametric analysis was carried out, using a one-dimensional model developed and validated in a previous work, in order to investigate on soil temperature changes induced by variations of the most relevant variables involved in the physical processes of the soil-mulch-greenhouse system. The model calculates temperature and moisture content in mulched soil, as well as air temperature and relative humidity inside the greenhouse. Specifically, temperature and water content in soil are calculated using coupled partial differential equations of heat and moisture diffusion. The required input variables are outside air temperature and relative humidity, outside solar radiation flux, wind speed, soil texture and bulk density, soil-mulch distance and radiometric properties of the soil as well as of the covering and the mulching films. The results allowed determining the optimal combination of climate conditions and physical properties of the soil-mulch-greenhouse system that allow the best increases of soil thermal regimes.