Soil Solarization Poly Films
Width range: 1 to 8 meters (3’-26’)
Soil borne diseases and pests cause major loss of crops in the field. Soil borne diseases, weeds, and nematodes have been partially controlled by soil-applied pesticides, including methyl bromide, chloropicrin, and methane. Soil solarization, a nonchemical technique, controls many soil borne pathogens and pests.
Transparent polyethylene plastic placed on the soil during the hot summer months increases the soil temperature to levels lethal to many soil borne plant pathogens, seedlings (including parasitic seed plants), nematodes, and some soil residing mites. Soil solarization also improves plant nutrition by increasing the availability of nitrogen and other essential nutrients.
Maximum soil heating occurs when the plastic is close to the soil. Therefore, it is important that the area to be treated is leveled and free of weeds, plants, debris, and large clods which would raise the plastic off the ground.
The area should be treated with a rototiller or by disking, or turned over by hand and raked until smooth to provide an even surface, this will help water penetrate and moisten the soil profile.
Soil must be moist for maximum effect. Moisture not only makes organisms more sensitive to heat, but it also conducts heat faster and deeper into the soil. Soil can be moistened by pre-irrigation, by drip or furrow irrigation, immediately after which the plastic should be applied over the soil. Irrigation under the plastic usually controls pests slightly faster and to a greater extent than when irrigation is done before the plastic is laid.
Benefits of Soil Solarization:
- Disease control.
- Weed control.
- Nematode control.
- Increased plant growth response.
Fumigation with Methyl Bromide:
- Methyl Bromide (MBr) has been the soil fumigant of choice since the early 1970's, mainly because of its high efficacy under a wide range of conditions. It is typically injected into an area covered with plastic film, standard polyethylene film is used because it is less expensive and easily accessible, but it becomes highly permeable when it comes into contact with MBr.
- With the phasing out of methyl bromide, growers will have to rely on other pest management approaches, including plastic mulch films with less gas permeability.
Many different experiments were conducted on the methyl bromide emissions from standard fumigation film. Much of this research appears to show that as much as 40 to 90% of the methyl bromide gas can seep through the LDPE plastic mulch cover. In general, a large proportion of the methyl bromide applied volatizes from the soil within the first 24 to 48 hours after applied. The percentage of the methyl bromide gas that can pass through the plastic is based on the thickness, density, and chemical composition of the mulch plastic. A high barrier film should be the one used with methyl bromide instead of a standard film.