cover with tarpaulin - Right Or Wrong?

personally i mainly use covering as a weed suppressant to try and save some time in the spring when there's plenty to do.

i try to spread manure, old compost, mulch, etc on the ground before covering to let the worms do their business. i do find under the waterproof cover needs a generous watering before covering and regular (monthly) lifting, checking and dampening if needed.

They break down differently to garden compost and such like, so therefore in theory the decomposition process should not rob any nitrogen from the soil like fresh manure would.

I'm not sure if that statement is strictly true - anything that is composted down will initially rob the soil of nitrogen as soil bacteria and fungi take it up to multiply but when they die off, the nitrogen is returned to the soil.

However, I do dig trenches and fill with leaves and some other stuff for composting and back fill with soil in some of the beds with heavy clay - these beds are used for summer crops such as winter squash and sweetcorn that don't get planted until late June.  I'm not sure the leaves add that much nutrient but they do break down and improve the soil structure immensely.  When I plant out, I usually toss some chicken manure into the holes.

I've covered my bare patches partly with green manure which was grown earlier in the year, and cut down to use as mulch, and also with cut down crops - beans, courgettes etc. Next spring anything un-decomposed can be raked off and composted, but the bottom layer has usually decomposed and been keeping the worms busy.

Strictly speaking, as BabbyAnn has already mentioned, high carbon materials containing little nitrogen "borrow" rather than "rob" the soil of nitrogen, although the effect can be the same in the short term.

What such materials can't do is suck nitrogen from the soil if they are lying on top of it - a leaf or wood chip mulch will not deplete soil nitrogen, although it will take longer to decompose having no access to nitrogen to feed the microorganisms which bring the process about.

Fresh manure may contain lots of high carbon bedding material, but that should be balanced out by the nitrogen from the urea in the bedding.

As for covering, a waterproof tarpaulin would avoid the leaching effects of winter rains, and should warm the soil a little in spring - against that is the possibility of harbouring slugs, reducing the beneficial effects of frost, and preventing access to birds and other beasties which can help reduce pests.

I prefer to leave the soil bare, but with very sandy soil there's not much left in the soil in winter to try to preserve anyway  , so I leave turning in well rotted compost or manure until early spring.

On sandy soils like ours Jay, they need the winter rain - some of my plot would be a dry beach, come spring, if I covered it with tarp 

Too true Mum (mind you, samphire might like it and we could be rich beyond our wildest dreams, not to mention super-trendy!  )

Seems it's a bit 50/50 as to cover or not.  One of the old boys on our lotty said don't cover and break up the soil but leave in big lumps as the frost has a better chance of giving the soil a positive effect.  However, can I ask a couple of questions along similar lines. 

A, When people say nutrients leach away.  Where to?
B, I have a shed load of well rotted manure.  when is the best time to lay it on the plot?

A) Into the groundwater, although some will run off the surface if your soil is that way inclined. Where the groundwater finishes up depends on your local geography, but much finishes up in rivers or eventually in underground aquifers, some of which are used for drinking water.

B) Anytime, but if you leave it 'till spring you will need to fork it in as the worms don't work that fast!

Brilliant, thanks, so as regards to nutrients being washed away it's better to add some form of feed, ie; pellets, bfb to the soil prior to planting?  Would that be enough to help the growth?

So many variables - much depends on your soil type, how rich the manure was, when you applied it, how wet the winter turns out to be.......

At best you shouldn't need additional fertilisers, at worst you can't grow things well without them, but artificial fertilisers are an example of a good thing that you can have too much of, so use cautiously.

Ta very muchly