Imagine harnessing the sun’s energy to destroy pests.
Like Archimedes, the ancient Greek whose “solar death ray” used mirrors to burn a Roman fleet, farmers, gardeners and landscapers can destroy or disable insects, diseases, nematodes and weeds in the soil without toxic pesticides.
The technique known as solarization consists of laying a clear plastic tarp on moist soil and letting the sun’s rays heat the soil. This process is occurring at the Mace Ranch Park Passive Recreation Area to prepare the ground for planting of native grasses in October.
In solarization, heat is trapped under the plastic, raising the soil temperature to kill or debilitate pests. Most of the research worldwide has concentrated on hot and arid areas, but anyplace with hot summers has the potential to use this system, a city of Davis news release said.
Usually, this soil pasteurization process takes four to six weeks, but the amount of time depends on many factors, such as rain, wind, day length, soil texture and the quality of the polyethylene tarp. Ultraviolet-protected plastic is recommended so the tarp can be removed and re-used.
Before solarization takes place, the land that is to be seeded or transplanted must be prepared for planting, the news release said. Ground must be leveled, beds shaped and an irrigation system installed. This is to avoid stirring up the soil after solarization, which would bring fresh pest organisms to the soil surface.
Depending on the outside temperature, sunlight density and the type of pests, soil solarization can provide good pest control 8 to 10 inches deep, the news release said, although best control is generally obtained down to 6 inches.