Soil solarization is a method of controlling soil borne pests. It works by placing a plastic sheet on top of moist soil (typically 70% moisture) during hot summer months. The sun’s solar energy then heats the upper part of the soil, which then gets trapped in by the plastic, which kills many disease-causing pathogens, weeds, and seedlings. The plastic is left on for typically 4-6 weeks. Typically clear 2mil plastic is used, though coloured or black plastic can also be used if left on for longer periods of time. Because it uses the sun’s energy, it is non toxic and can be used on both a small and large scale.
Soil solarization helps to improve soil structure, increases the availability of nutrients, and can reduce the need for chemical pesticides as well as increase yields for subsequent generations of crops. It is typically done in warmer climate regions such as California.
Soil solarization can be adapted during cooler periods of the year, though the effectiveness of destroying harmful pathogens will be diminished due to the cooler weather.