Effect of solar heating of soils by transparent polyethylene mulching on their chemical properties

Solar heating of soils by mulching with transparent polyethylene during the hot season results in increased soil temperatures and the killing of certain pathogens. Mulching increases temperatures by up to 10 to 12°C in the upper soil layer. We studied the effect of this treatment on the chemical properties and hydraulic conductivity (HC) of soil. Field experiments showed enhanced plant growth in solar heated soils, even in the absence of known pathogens. Saturated extracts of the upper soil layers of eight different solar heated soils showed increased concentrations of soluble organic matter and minerals. The greatest increase was in NO₃⁻concentration; NH₄⁺, K⁺, Ca²⁺+ Mg²⁺, and Cl⁻were also found to increase. Changes in soil pH, total organic matter, NaHCCv extractable P, and HC were small or inconsistent. Tomato seedlings grown on extracts of heated soils showed enhanced growth in comparison with seedlings grown on extracts of unheated soils.