Re: Solar blanket vs black plastic
- To: Multiple recipients of list <email@example.com>
- Subject: Re: Solar blanket vs black plastic
- From: Bill Shear <firstname.lastname@example.org>
- Date: Fri, 5 Sep 1997 11:18:14 -0600 (MDT)
The "kill" mechanisms of clear plastic and black plastic are different and
may account for the different observations. Clear plastic allows light
through, which then heats up the surface. But the heat is trapped under
the plastic and anything alive is cooked. It will kill everything,
including seeds and spores and many bacteria and fungi, provided there is
enough sunlight, as in California.
Black plastic, on the other hand, while getting quite warm itself, prevents
light and heat from reaching the soil. Plants are deprived of light and
slowly die as they exhaust their food reserves. This can take quite a long
time, for example, for a dandelion with its long, food-storing root. Seeds
are not killed, nor are fungi, spores or bacteria.
Clear plastic is much more effective and quicker. But it relies on having a
good number of sunny days to work with. The slow smothering effect of
black plastic may work better in cool rainy climates.
Department of Biology
Hampden-Sydney VA 23943