polythene pn beds over winter

[arwin]

Hi - I am thinking about covering my allotment beds with polythene over the winter. I would cover the soil with compost first abd let the worms bring it down over the cold period. Does anyone do this? Do you use clear or black polythene?
Cheers Arwin
PS someone posted about Joan J raspberries. I can recommend them as delicious and very big.

[sandersj89]

According to:

http://plasticulture.cas.psu.edu/P-Mulch.html

Clear plastic is better for raising soil temperatures but there is a down side in that weed control may be an issue for a time.

Clear plastic over manure may well be a good combination.

HTH

Jerry

[Johnboy]

Hi Arwin,
For the purpose that you wish to use the polythene
BLACK polythene is best. By keeping the whole thing in the dark you get far better worm activity and you do not get weed germination.
People who look at a horticultural piece of land that is covered with clear polythene assume wrongly that it is a soil warming execise but when clear polythene is employed it is for protection of something growing beneath it.
To use clear polythene over manure would have a tendency to bake it hard and slow the the biodegrading action it is heat from within that is needed not from outside.
Black absorbs heat, White repels heat but am not quite sure what Clear does apart from allowing weeds to grow. There is a polythene made which is black one side and white the other and black on the outside allows heat in and the white on the other side prevents from being lost. Don't ask!!

[sandersj89]

Johnboy

We use CLEAR plastic at home on the farm commercially to raise the soil temp, as the link shows it is better from a thermal point of view and will raise the soil temp faster than black.

Thus, daytime soil temperatures under clear plastic mulch are generally 8 to 14° F higher at a 2-inch depth and 6 to 9° F higher at a 4-inch depth compared to those of bare soil.

There is a down side as I said concerning weed seed germination in that the seeds germinate quicker, but this can be over come if the plastic is left in situ for long enough as heat in early spring summer is high enough to kill off many seedlings, solarisation. If you cant leave it in place that long it is easy to weed the bed early in the season as the weeds are easily visible. (Also chemical control is more effective earlier in the season with the soft new growth if you want to go that route)

If black plastic is used, and it will help raise the temperature, it will still allow weed seeds to be viable over winter, it simply delays the majority of germination until after the plastic is removed. Under clear they will germinate whilst the plastic is in place.

Clear plastic over manure, over a few months of winter, may have a degree of bake but the time will on the side of the worms.

I am sure we both agree that what ever plastic used it will reduce the leaching of nutrients from the soil due to rain fall....if we ever get a decent amount this winter/spring.

We have found clear plastic to be very effective and easy to use gaining us 3 to 4 weeks for root crops such as parsnips.

HTH

Jerry