Before - Weedy Unplanted Garden
I have three areas for vegetable gardening, each about 20' by 30' that are used for crop rotation each year. It's probably better to have four, so that the same plant in the same family (tomatoes, peppers, potatoes and eggplant, for example) is only planted in the same spot once every 4 years. Here's a good fact sheet explaining the how's and whys for crop rotation in the home vegetable garden. Still, fungal pathogens, weed seeds, and insect pests can accumulate over the years to intolerable levels. 2008 and 2009 exhibited climatic conditions that favored their build up in the soil. So this year, and (depending on how well it works and degree of difficulty), for the next two years, I'm going to try solar sterilization of the soil as a passive method to rid the garden of them.
Same area - different angle
The idea is to use the power of the sun to heat the soil as hot as possible to kill weed seeds, fungi, and pests, in the same way your compost pile heats up enough to accomplish the same thing. Ideally, getting the soil to a temperature of 140 degrees to a depth of 6-8 inches, is the ultimate goal, although you'll never get that and Pennsylvania summers generally don't get as hot (this year might prove to be an exception) for a long enough period as in the South, where this process works better and 100+ degree days can last for weeks. Still, it's worth trying, since most soil organisms are negatively affected with temperatures as low as 104 degrees.
After tilling, different angle
The process is straight forward. Till the area, wet it down (laying soaker hoses down is also recommended, too, to prevent drying out), and then cover with clear plastic. The plastic acts like a magnifying glass, enhancing the sun's radiation to raise temperatures enough to kill everything.
After wetting down
After wetting down - different angle
This process also kills the beneficial bacteria and micro organisms that are necessary for healthy soil, so it's important to restore that environment afterward. So, probably around Labor Day, I'll remove the plastic, spread the, er, 'output', from under the chicken coop, add as much compost as I have, and either plant a cover crop, or mulch heavily (thinking about experimenting with a home version of "no till" farming - still working on that in my head), depending on my mood, cost, and availability of material.
Plastic down - different angle
(That's Jason, giving me a hand this weekend)
This will be my bed for next year's tomato patch. The plastic is the stuff used to wrap my screened-in porch during the winter to provide a bit of protection from winter north winds, as a way to protect the porch furniture, and provide a little insulation to reduce heating costs. It gets pretty ragged after a winter season, and can rarely be reused for its original purpose, so this is a way to extend its useful life.