Re: Solar blanket vs black plastic

GSJW1010@aol.com wrote:
> 
> Hi....I have been following the conversations on the different types of
> plastic, and thought I would tell you my results.
> I am  working on two areas for spring, and had one garden covered with clear
> plastic, and the other covered with black plastic and  a tarp.   They have
> been covered 8 days as of today, and I have to tell you the clear plastic has
> already killed off the grass.

--  snip  --

I thought I would add in another of my two bits on solarization. One of
the keys to its effectiveness is the insolation (no not insulation,
insolation). Insolation is the rate of delivery of solar radiation per
unit of horizontal surface. The more directly overhead the sun is, the
greater the insolation. So the best days for solarization are those days
on either side of the summer equinox. After the equinox, the sun starts
moving south again and so the vertical component of the radiation starts
decreasing (unless of course you are south of the Tropic of Cancer
(approx 23 1/2 degrees north latitude which would give you a double set
of maximums of radiation each year). To be most effective, one would
solarize for an equal number of days before and after the equinox.

There is also an effect of the temperature of the surrounding soil. The
build up of heat in the earth lags the rate of insolation by a certain
amount, but I am not sure how much this affects the process. I'd have to
hit the books to figure it out.

John                     | "There be dragons here"
                         |  Annotation used by ancient cartographers
                         |  to indicate the edge of the known world.

John Jones, jijones@ix.netcom.com
Fremont CA, USDA zone 8/9 (coastal, bay) 
Max high 95F/35C, Min Low 28F/-2C average 10 days each
Heavy clay base for my raised beds.
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index