Polytunnel - Saline Soil???

[SMT]

I cant remember where I read it but somewhere said that if you dont uncover your polytunnel through the winter months you will get an increase in salts in the soil from excess fertilisers. It suggested the winter rains and frosts would wash away the excess ferts to prevent the saline conditions occuring.

Anyone heard of that? Or do people have a lot of success without bothering? It not exactly the easiest thing to remove a poly sheet. This is my first year with the poly and dont want next year to be a wasted season.

Many thanks

[OverWyreGrower]

We got our tunnel in May, and in all the reading up and speaking to people etc I've done, it's not been said anywhere to uncover it...

Besides, I don't see how most people could? Their plastic will either be trenched or nailed to base rails....

[Tomatoking]

In the 'old days' before I grew tomatoes commercially in glasshouses in growbags, we used to grow directly into the soil, so we used to leave the overhead water sprinkler lines on to purge the soil with water for a few hours.
However, this was commercial crops with a long season and fed with fertiliser with every watering, then we used to steam the soil for a few hours to eradicate disease.
However, in home glasshouses you would not have been feeding so often and yours is also fairly new, so I do not think that you would have an excess build up.
It is a good idea if your glasshouse or tunnel is totally empty over the winter, to wash it down with a disinfectant, then rinse off after a few hours, this will kill most bugs, but maybe like me, you will over-winter some crops, so this is not always possible.
If after a few years you get soil borne diseases, then you could grow in growbags for a few seasons, although growbags take accurate watering quite a few times a day in the summer, if you water too heavily, you end up purging the bags of the slow release fertilisers that they are made with.
A better system is raised beds made with small posts, polythene and string, which will give you a larger area to grow in and will not dry out as quickly as growbags and you could change the compost every few years or so.
I hope I haven't gone on too much, but if you do need anymore info from my rusty brain, feel free to ask.

[SMT]

Overwyregrower - I couldnt really see how to easily uncover the poly either. Though, I could lift mine up a certain degree as its on aluminium base rails. Though this would defeat the object as the polythene wouldn't be taught and allow the wind to whistle through. So I would probably lose the sheet to wind damage anyway!

Tomato King - Thanks for the info. I just have some potatoes left in bags for christmas and a few parsnips left in the ground. Once they are gone I planned to clean up and disinfect. Half the poly is all ready cleared and dug over where the pumpkin plant was. Its the pumpkin feeding regime I worry about I suppose. As I try to grow giants for competition (675lb this year) it requires a lot of feeding. I should probably purge the soil this winter aswell in that case?

[Tomatoking]

SMT- If you do give the soil a good soaking, make sure it has plenty of time to dry out again and make sure you add a nice lot of well rotted compost, to add some nutrients back into the soil. But it sounds like you know what you are doing anyway.

[Snadger]

I haven't got a polytunnel, but the leaching of salts issue is a long standing one among glasshouse growers.
Tomatoes crops grown in the greenhouse bedsoil deteriorate over a number of years and if you want to keep using the bedsoil the only solution is to change it. Adding organic material may help a bit but sometimes a soil change is the only solution.
This doesn't need to be done every year, but I reckon every 2 or three years with loads of moisture and manure added in the years in between.

I like to think you can tell how fertile a soil is by how many worms are within it..............lots of worms= fertile soil..............few worms = time for a soil change!

What I did was grow for a couple of years in the bedsoil then cover it with pea gravel and use either ring culture or pot growing methods, allowing the water seeking roots to grow into the ever moist pea gravel!

[SMT]

... and make sure you add a nice lot of well rotted compost, to add some nutrients back into the soil.But it sounds like you know what you are doing anyway.

Yeah otherwise my pumpkin will look somewhat deflated!

Thankyou for the advice. As for 'knowing what I'm doing' - I think a lot of luck has played a big part so far.

Ill bare the soil changing in mind snadger. The soil levels are on the low side anyways so wouldnt be too big a deal when the time is right - if I need to.

[ken smith]

It is not practical to remove covers so I never use chemical fertilisers in my tunnels. I usually dress the soil with F.B.and B and then feed with nettle or comfrey tea. During the year, whenever a bed is empty, I give it a good soaking.