5 Short Notes On Solarization
What kind of plastic and how big?
Any clear, UV stabilized plastic works (generally 6 to 8 mil thickness is best, thinner punctures and rips too easily, thicker is more expensive and much heavier). I like using leftover or previously used greenhouse plastic instead of new plastic whenever possible. Plastic should be 2 feet larger on all sides than the area you want to cover.
Do I have to bury the edges?
Yes. It will be far more effective and efficient if fully buried along all four edges. A trench at least 6 inches deep is ideal, with the dirt removed from the trench then replaced on top of the plastic that was laid down in the trench.
How long do I leave it and does it harm the soil?
Solarization takes anywhere from 7-14 days, though in extremely hot and sunny weather, may be sufficient in as little as three to five. It is best done as close to mid-Summer (July/August) as possible. A lot of factors impact how successful it is, such as slope, weather, location, soil type, and more, which is why an entire section devoted to this subject in my book.
No, solarization doesn't harm the soil food web, big or small. Numerous studies have shown that the soil benefits from processes like solarization if it is done properly.
How effective is it?
Solarization removes 100% of live plants and 95-98% of seeds in the top few (3-6) inches of soil if done correctly.
It even helps reduce, remove, and deal with those pesky rhizome reproducers whose roots and shoots often run through the loose, shallow top few inches of soil.
In some soils, or through incorporating biomass, soil can be simultaneously improved, weeded, and cleared of pathogens and some soil borne pest species 12 inches deep or more.
If you are interested in learning more about soil, check out John’s basic soil course!
Or email firstname.lastname@example.org to reserve a copy of his forthcoming book.