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mulch/manure/improving clay soil

(22 Posts)
NotAnEMERGENCY Mon 20-Mar-17 11:33:36

I have clay soil. It's not as bad as some clay but it could obviously still do with improving!

Last Nov when the bed was empty, I dug in a tonne (1,500 litres) of horse manure, which has helped a lot already. I believe it is now time to add mulch/manure/compost again on the top so the worms can continue the work.

I don't have nearly enough home-made compost yet and I've heard that the bags of multi-purpose compost you can buy don't do much for soil improvement. I can use leaf mould in future but mine's not ready yet.

The bed is 20 sqm. There's not too much planted in it yet so it's quite accessible still.

At a local independent garden centre, I have the following choices:

3x 50l Arthur Bower's Organic Farm Manure for £10
3x 50l Arthur Bower's Mulch and Mix Composted Bark for £12
1x 50l Westland Soil Conditioner for £5

Which of these would be best? Are the ones that cost more 'better'?

shovetheholly Mon 20-Mar-17 11:48:08

Wow, that's a LOT of manure and a LOAD of digging! Well done you! Multi-purpose compost will improve the soil a lot in the short term, but (like manure) it will rot down and require replenishment. The same is true of all organic mulches, however. What are you intending to grow? If it's heavy feeding veg, then loads of manure is fine - if it's herbaceous perennials, then you can go too far sometimes!

A more permanent improvement can happen with something inorganic like horticultural grit. I'd be tempted to use a mixture of this, a bit of gypsum, and compost - with the last, cheap, cheap, cheap is fine. I often use the peat-free stuff from the council, which is 4 large bags for a tenner. It's a bit rough and ready, but that actually is fine for a soil improver.

NotAnEMERGENCY Mon 20-Mar-17 12:17:12

The digging was hard work but I felt I had such a unique opportunity with the bed still being bare. Now I'm happy to let the worms take over!

This bed is for perennials/shrubs. I have another bed that will become a veg bed in future but I'm concentrating on the flower bed for now - I don't want to take on too much at once. It's overwhelming enough as it is!

My local council tip doesn't do compost (boo hoo).

The garden centre I mentioned does both RHS Gardener's Collection Grit Sand and RHS Sharp Sand. Is there much of a difference? The price is the same: £2.99 for a 'handy pack' or £5 for a 'large pack' (3 for £12). Unfortunately, no volume or weight mentioned.

Eatingcheeseontoast Mon 20-Mar-17 12:27:15

I have an allotment on very heavy clay soil. I use raised beds which help a lot which you might want to think about for the veg plot. (Google lasagna planting).

Mulch, mulch and more mulch. I have a compost heap, collect leaves to rot down over the winter, buy cheap soil conditioner if I see it on sale or cheap multi purpose compost, use lawn clippings as mulch, I have bark on the paths so when that has rotted down and needs replaced I put it on the beds, seaweed (very good for clay soil but a bit stinky if left uncovered and not dug in).

I do very little digging as it's hard work on clay and mostly let the worms do the work of dragging stuff down.

7 years on I have really very good soil. If I could just get the pigeons to bugger off it would be great.

There's differing opinions on whether adding grit or sand makes much difference in the kind of quantities most of us can add it.

shovetheholly Mon 20-Mar-17 12:29:53

Personally, I use actual grit - i.e. small stones - not grit sand. That's because I worry about adding sand to clay making it seize in hot weather, whereas larger pieces open up the soil a bit more. I am not a soil chemist, so I go for the low risk option! smile Think it's roughly the same price as the sand you mention.

What does your soil look like? Is it still in big clods, or has the weather broken it down? If the texture looks decent, you could just dig large planting holes and fill the bottom with grit and compost as you plant up, then mulch inbetween to suppress weeds? (Obviously, if it's still terribly lumpy, more working/addition may be needed! I once had a garden on stuff that was literally like potter's clay - it took a LOT of breaking up) Many clay soils don't need that much in the way of added nutrients as they are quite nutrient-rich as it is. The same thing that retains the water (small particle size, large surface area) retains food too!

NotAnEMERGENCY Mon 20-Mar-17 12:58:09

Won't using lawn clippings make the bed look messy? How long does it take the worms to work it into the soil?

I don't think the soil needs extra nutrients so it's really just a matter of making the soil more workable and improving the structure (currently soggy in winter and baked in summer - makes me unsure whether to choose plants that like dry or moist conditions confused). The bed is a bit raised already though so that's not too bad either.

The clods are perhaps 5cm in diameter? It varies quite a lot. I'm pretty sure that doesn't count as big but I certainly can't rake the soil! Some clods I can crush fairly easily between my hands (if it's dry) but some clods just stay as a squished ball.

So maybe horticultural potting grit like this to add when planting and farm manure for laying on top of the soil to mulch in spring & autumn?

Ohyesiam Mon 20-Mar-17 13:00:15

The first and the last one on your list are best, but it's an expensive way to buy manure. You can usually get of free from riding stables, of a tonne delivered for about£ 20.
Sounds like you've done really well with it though. If it's was just for shrubs and perennials I would be tempted to leave it at that. I have one clay bed, with roses, bulbs perennials and shrubs, which all do well, and I've barely improved the soil at all.

shovetheholly Mon 20-Mar-17 13:08:45

It's quite early, and the soil is quite wet still - it may be different in 6 weeks or so if we get a dry spell! <fingers crossed>smile

I just keep adding, adding, adding, grit and compost, year in, year out. smile. Grit is expensive, though, as a PP rightly pointed out. You could always compromise by adding it to the bottom of planting holes initially, along with loads of compost, and then mulching the top of the soil and letting the worms break those small clods down over the season. smile

Qwebec Thu 23-Mar-17 00:50:08

Unfortunatly, research has proven that adding grit is a really bac idea. It will turn you soil into concrete to learn the details why and what to do here is a link from an known Candian gardener laidbackgardener.wordpress.com/2015/11/27/gardening-myth-adding-sand-will-loosen-clay-soil/

Adding organic is the secret as said above.

shovetheholly Thu 23-Mar-17 10:04:13

FFS, my phone just lost a long message!

Semantic problem. In gardening "grit" = horticultural grit = gravel. Loosens soils well when used with organic matter.

Across the pond/in building trade "grit"= sand. Can cause certain soils to seize in summer so best avoided.

shovetheholly Thu 23-Mar-17 10:09:41

Picture of horticultural grit. Don't ask me why it has a jammy dodger in it. It's a marketing technique I haven't seen before... grin

NotAnEMERGENCY Thu 23-Mar-17 10:14:20

Perhaps they are suggesting jammy dodgers are good for improving the soil too?? grin

traviata Thu 23-Mar-17 10:14:36

Biscuits are optional when loosening clay soil, but are recommended afterwards with a cup of tea.

ElasticFirecracker Thu 23-Mar-17 11:36:20

I have clay soil and I've used mushroom compost. I order great big cube shaped bags like builders use. They cost about £75 each and it's the most cost effective thing for me. I can't remember the actual quantity but the bag is at least 1 cubic metre.

Eatingcheeseontoast Thu 23-Mar-17 11:39:05

As elastic says - mushroom compost - it's brilliant stuff - I use it loads. And its light to lift and you get the bonus of a crop of mushrooms too.

Qwebec Thu 23-Mar-17 16:39:13

I did not know the different cultural meanings of grit!
I'm so rubbish at confrontation I usually never revisit a page where I contradict someone. And shovetheholly you are so knowlegeable, it just makes it harder. But (puts brave pants on), I don't agree that UK grit is better for drainage (the article explains why). Yearly mulshing is the better way to go, or adding a good layer of top soil.

But feel free to disagree and jammy dodgers for everyone.

GingerKitCat Thu 23-Mar-17 21:50:10

biscuit biscuit biscuit

This thread has been educational!

shovetheholly Fri 24-Mar-17 08:00:48

grin I'll be too busy eating those jammy dodgers to be confrontational qwebec!

I'm also at the limits of my knowledge here. I did a bit of soil chemistry when I did a biology degree a while ago, but really all I took from that was that soil is complicated! grin I'm not a natural born scientist, that's for sure. I use horticultural grit in my garden without any problems with soil seize - the particle size in the RHS bags is quite large and it seems to introduce "gaps" into the clay that kind of break it up, IYSWIM. I have made the mistake of adding horticultural sand to a previous garden that was literally on a clay pit, and I did get seize there - it was like the sand enabled the soil to shrink in on itself and become brick-like in hardness, which is almost the opposite effect. BUT in my current garden I also use huge quantities of organic matter AND I'm north-facing so it tends to stay fairly moist even in hot weather. I imagine all those things make a difference!

RedBugMug Fri 24-Mar-17 08:03:56

how about compacted coconut fibres?
you get them in the pound shop. you activate with water and a small pack makes 10l of 'compost'.

AndromedaPerseus Fri 24-Mar-17 20:49:52

I collected the fallen leaves from our tree in November and put a thick layer on top of my clay soil. Went to plant some bulbs this week and the leaves had pretty much disintegrated into the soil which was lovely soft and moist with plenty of fat worms in it

NotAnEMERGENCY Wed 29-Mar-17 14:05:41

Thanks for all your input - very interesting!

I've had a look online at mushroom compost and the cheapest I've found is 7p per litre. However, for that price I need a min order of 1200l. The organic farm manure I can get for the same price per litre but the min order is only 150l. Of these two options, therefore, the farm manure is better for me.

However, Morrisons have now started selling their cheap (peat free!) multi-purpose compost again (40l for £2). At 5p per litre, this is definitely the cheapest option (and the bags are smaller so easier to lug around). Would it be a mistake to get multi-purpose compost as a mulch for my clay soil instead of the farm manure? As I said, it's just for shrubs and perennials, not veg. Or is even the bought compost overkill?

shovetheholly Wed 29-Mar-17 14:18:18

I would be very surprised if the Morrisons stuff is too much for a clay soil. 5p a litres is good value, I would definitely go for that!

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