Soil Solarization as an Alternative Weed Control Method for Archaeological Sites in the Mediterranean Region

Weed species commonly colonize archaeological sites in the Mediterranean region, which poses many issues for the sites’ function and the state of preservation of the monuments. Soil solarization was investigated as an alternative environmentally friendly weed control strategy following legislative limits on the use of herbicides at archaeological sites in Greece. The aim of the study was to evaluate the effectiveness of solarization applied during: (a) summer (the hottest season, as applied in organic and integrated agriculture) and (b) autumn (a season of low tourist activity in archaeological sites), testing two types of plastic mulching: (a) clear and (b) opaque black, and two types of soil preparation: (a) with tillage (as in the agricultural practice of the method) and (b) without tillage. Visual evaluation of the weed control rate suggested that the application of soil solarization during summer resulted in excellent weed control, 100% the following October to December period and over 90% until February. The application of soil solarization during autumn also provided excellent weed control and treatments with clear plastic and tillage resulted in complete (100%) weed control from October to December, while the following month weed control was over 90%. In late March, dry weight of weed biomass was significantly affected by the solarization treatments and it was significantly reduced by treatments with clear plastic. Thus, soil solarization is a sustainable method that has the potential to be used effectively for weed management in archaeological sites of the Mediterranean region. Even treatments without tillage generated excellent weed control during the winter weed flush period and are recommended to protect unexcavated, fragile artifacts. Also, the results of autumn treatments encourage the application of the method during the season of low tourist activity at archaeological sites.