I've been thinking about the response I got to my solarizing blog (Solarizing and Vinegar: organic weed control) from someone who thought it would kill the beneficial organisms in the soil. I wanted to research better minds than mine about this before responding. Glad I did, 'cause I always learn more this way.
I will now quote from my well-worn Rodale's Garden Problem Solver. (be sure and read this to the end about solarizing's effect on beneficial organisms)
"Solarization was developed in Israel and has been tested at a number of universities across this country. It is a process that produces very high levels of heat and humidity in the soil, which pasteurizes the soil, destroying harmful bacteria, fungi, some nematodes, virtually every type of insect larva, and the stock of weed seeds near the surface.
Solarization has been found to be an effective control against such pesky disease problems as verticillium wilt in tomatoes, potates, and eggplants. It knocks out fusarium wilt in tomatoes and onions. It is effective against rhizoctonia in potatoes and onions, and eliminates a variety of nematodes that attack potatoes and other crops.
An unexpected and unexplained benefit of solarization is that it also enhances the soil's ability to grow especially robust and healthy plants. Greater yields have been seen in beds that have been solarized. Solarization destroys harmful organisms, but it seems that certain beneficial organisms are not harmed.
Jim DeVay, chairman of the plant pathology department at the University of California at Davis, is quoted as saying: "While many fungi, bacteria and other pathogens are killed, certain fungi that play an important role in utilization of plant nutrients and crop development withstand the heat and survive."
See my updated post "Solarizing and Vinegar: organic weed control" for 'How-to' instructions.