Improving the soil

[Argonaut]

I have very bad ground .... it was a site that was built up by over 20' back in 30's to become a railway sidings .... what they built it up with is steel works slag & subsoil from nearby A road they were digging through a hill.
Disused since 60's it became eventually a SelfBuild site.

For my main veg plots I built up high raised beds and imported soil ... and over a couple of years with loads of manure & sharp sand have got this to good condition and very fertile.
But for borders and ground level beds ... although I dug out the 'sub soil' to a depth of 24' and put in imported soil it is very heavy - with high clay content, gets waterlogged.

Due to established plants SWMBO won't let me Rotovate it, so mass addition of anything is not an option.
I have come up with a plan B

I bought a hand operated 4" diameter Auger ... and have the idea that every 2' or so will bore put a 4" hole around 2' deep and fill it with sharp sand ... and top the last 2" with good loam.
Physically tried it and it bores the holes easily.

My thoughts being 2 fold ... vertical drainage will allow (by hydrostatic pressure) water to seep into the sand filled 'tubes' and help drain the ground.
and secondly over time the sand will mix in with soil by worm action etc. ,,, and improve the soil.

Anybody see any issues with this …. And maybe any improvement …. maybe something other than just sharp sand into the holes ?

[Bigmallly]

Sounds good Argonaut, I can't compare costs but wondered if Vermiculite/Perlite would do a similar job. With it being courser it may help more with your drainage problem.

[Bill Door]

A couple of thoughts on this.

1) you might need to go a little deeper. At least you will find out if you have the nasty grey clay beneath.

2) you might be better off adding grit and well rotted manure rather than the sand. You need something to break up the clay rather than "join " it. You also need worms to get there and work it all together.

3) Continually mulch the beds with leaf mould or your own compost.

Hope it all works out for you

Bill

[Argonaut]

What do you mean by grit ...
Sharp sand is very coarse compared to 'builders sand' .... In the books I have thet mention addinv coarse sa d to heavy soils.

Can you give a mesh size or diameter fir this 'grit'

[Bigmallly]

Other Products - Grit, Gravel and Sand

[Argonaut]

Did a google for it ... and found loads of posts saying people can't get this .... did find some of Amazon - but way too expensive.
Sharp sand is £43 tonne ... around £1.20 per 20Kg whereas buy it in 20Kg bags at Amazon it is 10 times that price.

I'll see if builders merchants can do 3mm gravel

[Cadalot]

Vertical sand drains in clay will make a repository for the water and lower depths could be filled with pea shingle to provide voids for the water, but you line lakes with clay to make them water proof, unless there are sand lenses or layers in the clay your water is not going to travel just stay and keep the lower layers wet.

If you had clay overlying chalk, or sand of gravel then if the vertical drains went into that the water would have somewhere to go. Soakaways in clay are a nonsense, it just holds the water which gradually evaporates as seeps via sand lenses.

[Snadger]

What you are basically doing is hollow coring with soil exchange. I have used this myself and it works if all you want to do is get water away from the surface. I would fill holes halfway with pea gravel then top off with course even grained sand.
I personally think that your 'Cores' need to be closer together and wonder what you are going to do with the resultant spoil?

[Argonaut]

I have a spare 1 tonne of 10mm chippings ... so could use that in bottom 1/2 of hole and top off with sharp sand.
At the moment have a barrow full of very sticky clay soil as spoil ... but still better than the original sub soil (contaminated land) so maybe I will look to make a heap of that and try and rotovate a load of organic material into it .. and improve that as a separate project. Clay usually has high nutrient levels so if I can improved texture it would still be usable.

I can get farm yard manure .. normally get full rotted cow manure (black crumb) to put in raised beds ... could get a load of sheep or horse manure which typically has loads of straw bedding .... and mix the lot and allow it to rot down.

Or as an alternative has access to seaweed could mix in a load of that and leave it in a heap for a few months .... hopefully worms will take hold as well.

[Snadger]

Any chance of a piccie of what you are up against Argo?

[Argonaut]

Not sure how much a pic will help ...
But here are 3 ..

The Top soil



The spoil 12" down



The spoil 18" down

[Snadger]

Not sure how much a pic will help ...
But here are 3 ..

The Top soil

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The spoil 12" down

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The spoil 18" down

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They don't look bad at all? If thats the way the soil is coming out you appear to have a decent loam and not solid clay as I suspected.
If what you are doing seems to be working, stick with it. The addition of course sand or grit will pay dividends in the long run.

[Argonaut]

On the raised veg beds ... I brought in several tonne of rotted cow manure & 2 tonne if sharp sand .... mixing all in layers.

Has been very productive for Beg and quality of soil inproved considerabky.
On the flower beds .. it has had sone manure and sand initially ... but as full of wifes flowers can't dig over to any degree.

Have been top dressing with fresh seaweed, sharp sand and calcified seaweed ..
This gets raked in and dispersed by rain ... but condition not as good as I'd like.
The main issue is drainage as not raised .. when we get a lot of rain it gets waterlogged.
Hence my thought introducing sand would help.
Put in another dozen holes today ..
1/2 filled witb 6mm sharp gravel an rest sharp sand.

[ESBkevin]

I think Bill Door has the right idea.

Any solid rock/sand items might give some instant relief but they won't sort the problem permenantly.

Worms and deep roots are the answer to breaking up the lower levels and creating perfect drainage. The way to get worms in is organic matter in any and all it's forms and keep topping up.
If you auger down, back fill with muck/compost anything organic to give the worms a start, otherwise keep piling the stuff on the top several inches deep. After 2 years you can auger down again and you will find the worms have dragged down the compost and the roots have followed, the clay will break up and water will be retained for the summer but drain away in a rain soaking.

Also if you have some fine organic crumble, add that with a little fine sand to the lawn for the same reasons.

The only reason to do any civil engineering is if the site is awash with other peoples run off.

[Argonaut]

The land that drains is 20' down.
All I can do is try to improve top 12-18"