Improving Subsoil?

Ahem!

I'm currently trying to replace an existing urban lawn (c.10m x 10m). The existing soil is very heavy clay, and over the last couple of years this has resulted in very poor drainage (inc. lots of standing water), and ever decreasing grass - basically it's drowning!

I've spent the last couple of days removing all the sod to a depth of about 5-6 inches and am now planning on rotavating it flat, installing a drainage system and recovering it all with newly purchased topsoil.

Basically I'm wondering if its worth adding anything to the subsoil at this stage too (I'm only planning on doing this job once, believe me!)? And if so what? Please bear in mind that I'm a rank amateur in the garden so I'd prefer something readily commercially available, and preferably not too expensive.

All advice gratefully received. - Thanks!

Nonmonotonic

This appears to be the best Boards solution. Great bit of work!

This is the de luxe version, you might want to simplify. If drainage is bad modifying the topsoil will not solve your problem. You can however improve the condition of the soil by mixing some kind of humus rich material through it ( manure, compost, spent hops ( used to be available from Guinness) peat, rotted bark mulch).

Ahem!

Thanks for that. That's pretty much the drainage system I had in mind. Slightly disconcerting to hear it took him a year though - I was hoping for more like a week!?!?!?!

With regards to the subsoil I've also heard a lot of people recommending gypsum as well as organic matter - and maybe even using sawdust. Anyone any experience of these? And any indication of appropriate quantities would be really helpful.

Thanks again!

Sonnenblumen

Ahem! wrote: »

I'm currently trying to replace an existing urban lawn (c.10m x 10m). The existing soil is very heavy clay, and over the last couple of years this has resulted in very poor drainage (inc. lots of standing water), and ever decreasing grass - basically it's drowning!

I've spent the last couple of days removing all the sod to a depth of about 5-6 inches and am now planning on rotavating it flat, installing a drainage system and recovering it all with newly purchased topsoil.

Basically I'm wondering if its worth adding anything to the subsoil at this stage too (I'm only planning on doing this job once, believe me!)? And if so what? Please bear in mind that I'm a rank amateur in the garden so I'd prefer something readily commercially available, and preferably not too expensive.

All advice gratefully received. - Thanks!

Ahem

Absolutley. If your problem is water lodging on surface, this suggests inadequate/poor drainage. To rectify matters, you will need to excavate deeper than 5-6 inches. In fact I would suggest you rotovate to at least 12 inches and more. This is very doable (< 1 day) with a heavy duty rotovator/mini digger. Mix in plenty of fine horticultural grit as well as reasonable soil mixed with pea gravel for 6 inches. Topdress ie replace top layer (top 6 inches) with good quality topsoil. Grade, level and roll. Do allow for compaction!! If you decide to opt for roll turf and not seed for new lawn, apply a layer of approx 1" lawn sand to topsoil surface.

This should be more than adequate for your site, however installing land drains would also be a viable alternative.

Ahem!

Ok. Valuable advice guys!

Sonnenblumen - Do you mean that the drainage system would be an alternative to the deeper excavation? The problem with further excavation in my case is the inaccessibility of the garden to a mini-digger or anything like that (its basically me and a wheel barrow!), and also of disposing of the waste inexpensively. If a drainage system of the type exemplified by the photos linked above is a viable alternative to that then I think I'll stick with it. Also , I already have a drainage pit of about 1m x 1m x 5ft deep dug out at the lowest point of the garden.

This still leaves the original question of the subsoil additive though? Any thoughts on that, or whether it is worthwhile? What about this gypsum stuff?

Sonnenblumen

Ahem! wrote: »

Ok. Valuable advice guys!

Sonnenblumen - Do you mean that the drainage system would be an alternative to the deeper excavation? The problem with further excavation in my case is the inaccessibility of the garden to a mini-digger or anything like that (its basically me and a wheel barrow!), and also of disposing of the waste inexpensively. If a drainage system of the type exemplified by the photos linked above is a viable alternative to that then I think I'll stick with it. Also , I already have a drainage pit of about 1m x 1m x 5ft deep dug out at the lowest point of the garden.

This still leaves the original question of the subsoil additive though? Any thoughts on that, or whether it is worthwhile? What about this gypsum stuff?

You should be able to take a rotovator through the house, you'll need someone to help you though. I still go with deep excavation and mix in suggested soil improvers (grit and pebble). I'm not clear what gypsum you are referring to? I know that traditonal techniques involved using lime to help breakdown heavy clay sods over winter months, but I doubt if this would make any improvement to drainage/compacted soil structure.

If you prefer and given you dug a sizeable saokage pit, why not install a radiating land drain throughout garden?

Why not factor in a Raised Planting Bed in some area, this will be a smart way of utilising excess soil?

paddy147

Ahem! wrote: »

I'm currently trying to replace an existing urban lawn (c.10m x 10m). The existing soil is very heavy clay, and over the last couple of years this has resulted in very poor drainage (inc. lots of standing water), and ever decreasing grass - basically it's drowning!

I've spent the last couple of days removing all the sod to a depth of about 5-6 inches and am now planning on rotavating it flat, installing a drainage system and recovering it all with newly purchased topsoil.

Basically I'm wondering if its worth adding anything to the subsoil at this stage too (I'm only planning on doing this job once, believe me!)? And if so what? Please bear in mind that I'm a rank amateur in the garden so I'd prefer something readily commercially available, and preferably not too expensive.

All advice gratefully received. - Thanks!

You spent the last few days removing the grass sod from a 10 x 10 meter garden?


1 of these and around 1-2 hours maximum would have it all done for you.You roll the grass up into bundles and simply lift it away.

35-40 euro a day to hire it out.:)


Rotivate the soil,then add in compost and manure and horticultural grit and rotivate again.

Nonmonotonic

Never seen on of those babys. Who did you hire from?



This is more likely to be at the hire place. Worlds worst design, digs to the centre of the earth on soft ground, skips on in hard!

paddy147

Its a petrol powered "turf cutter",that cuts down under the grass sod,and then you roll up the grass sod into a big roll and lift it up off the garden.

Its so simple and easy to use.It even has a forward,neutrel and reverse gear so all you have to do is walk with the machine and turn it,it more or less does all the work itself.

I hired it out from JW Hire in Dublin and most decent hire shops will have them and also petrol powered rotivators for hire from around 35 euro a day.

Nonmonotonic

Sod it, thought you were talking about a Rotavator!

magicbastarder

are you in a natural dip? i.e. i'm wondering if there's more factors at play than just the soil.

Ahem!

paddy147 - never saw that machine before. I doubt my sod would roll up anywhere though, its so compacted and either sodden or baked hard. Doing it by hand has also allowed my to remove a lot of rocks that mightn't have been helping either.

magicbastarder - no I'm actually fairly high, with open fields out the back that the lawn should (theoretically!) drain down towards.

Bearing in mind all the advice I'm going to proceed with the rotovation, addition of a mixture of manure, compost and grit, and the radiating land drains: then cover the lot with the new topsoil and reseed.

Any guidance on amounts of the subsoil additive mixture per m2?

Thanks again!

Sonnenblumen

Ahem! wrote: »

paddy147 - never saw that machine before. I doubt my sod would roll up anywhere though, its so compacted and either sodden or baked hard. Doing it by hand has also allowed my to remove a lot of rocks that mightn't have been helping either.

magicbastarder - no I'm actually fairly high, with open fields out the back that the lawn should (theoretically!) drain down towards.

Bearing in mind all the advice I'm going to proceed with the rotovation, addition of a mixture of manure, compost and grit, and the radiating land drains: then cover the lot with the new topsoil and reseed.

Any guidance on amounts of the subsoil additive mixture per m2?

Thanks again!

Ahem

You try to mix in approx 2 ton of hort grit, I'm not sure why you would use manure especially under a lawn area. Better to apply soil, some soil conditioner (compost) and grit and leave the manure for border areas.

Ahem!

Ok. Thanks guys.

I've found this grit relatively difficult to come by down this end of the country. I've found someone who'll deliver the 6 mill. variety. Is this ok or do I need to smaller stuff?

Sonnenblumen

Ahem! wrote: »

Ok. Thanks guys.

I've found this grit relatively difficult to come by down this end of the country. I've found someone who'll deliver the 6 mill. variety. Is this ok or do I need to smaller stuff?

Hunky Dory:)