Yes, I'm a bit doubtful about the people who claim to have added manure with no result. I'd love to know exactly what they did and how much they added because I just cannot understand how it wouldn't make a difference. The clay I have is about as dense as clay gets and I have transformed it. Where is all their manure going?!!!
I wonder if people underestimate how much manure or OM they need to add. Only a tiny amount of what you add actually persists long term. Perhaps people are expecting too much as well; you might be able to create a shallow topsoil layer that is nice and crumbly, but there's not a lot that's going to change underlying clay subsoil.
"What is hateful to you, do not do to your neighbour".
If the drainage isn't bad you can improve the soil by adding muck and possibly coarse grit - NOT sand of any type - but if you want to improve things in your lifetime, dig it in, break up the clay and mix it all well. Mulch as often as you can in following years.
Can't really add much more to what has already been suggested - but Posy is right about one thing - never add sand to clay to improve texture - it just makes things worse. It actually aids compaction. Grit is equally as useless - you need tons plus the end result is just gritty clay that still wont drain.
I would stick with no-dig. However, sometimes to kick start the 'no-dig process' its necessary to dig in really large amounts organic material - often just once is enough - then keep placing on the surface after that. I use manure & coarse garden compost.
I have a damp garden with silt and clay subsoil - it's taken a while to improve my soil texture (5 years) - but it's still a damp garden. I quite enjoy planting it with things that enjoy the conditions. The small veg garden is in raised bends 2 sleepers high but even they stay quite damp. I can grow most things - carrots or parsnips not so much but things like peas & French beans do OK.
There are plenty of people on the forum that say they have added manure for decades and it hasn't changed the clay at all. Generally people warn against adding sand.
As a quick fix, you might want to look at getting some raised beds going while you examine the clay situation.
Ten years ago, new to gardening, I took out many tonnes of clay by hand. I added manure and homemade compost and now I have great beds full of worms. My clay was not the solid stuff to make pots from, just very claggy soil with huge lumps in it. And my beds are small (1x2 metres).
When my children were small they would buy me bags of compost for Mother's Day instead of flowers. I even had a bag tied with a purple bow one Christmas, it was left on the patio .The dye came out of the bow and marked the patio!
I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
Over the years, I improved pockets where I wanted to plant, I've been at it for over twenty years and some of the pockets are joining up. I have used only my own compost and spent potting compost. It still baked and cracked in places but I can usually dig deep enough to plant things if I use the 3 or 4 day window that you get after rain. I don't think,even in my enthusiastic youth, I would have tried to do it all at once.
The ‘lay it on top and the worms will do the work’ approach didn’t work for me because my soil was extremely heavy (alkaline) pure compacted clay similar to @Posy’s, totally devoid of life and not a worm to be found anywhere. It was also a shallow layer, barely a spade’s depth before hitting an impenetrable hard pan/bedrock. I had to create raised beds to have any planting depth and initially dug in about 6 tonnes of manure/composted pine bark delivered in bulk in builder’s bags plus a couple of tonnes of grit. Subsequent years I had yet more tonnes of composted bark delivered and mulched heavily.
To avoid the problem @GardenerSuze mentions of plant roots hitting a solid layer of clay, I broke up the hard pan, removed loads of large stones and dug in the premixed new material to this base layer, then returned barrowfuls of the clay soil and forked and mixed in a greater quantity of new material, then added a thick layer of composted bark on top as a mulch. So the bottom layer has a higher clay content than the top but the transition was gradual and it was well mixed in to a plantable depth. By the time plant roots hit the base layer, it was not as hostile as it might have been and they were strong enough to penetrate it.
All this basically meant my soil was workable many years faster that if ‘left to the (nonexistent) worms’ but you do need, literally, tonnes of manure and compost 😊
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
@Nollie I had already planted a lot of my garden when I realised just how much of a problem the soil was going to be. I grew clematis for the first time and realised that they could not cope with the poor root run. At first I was disappointed that my garden would have limitations, then over time I accepted it. Because plant choice is limited I haven't been tempted to buy one of everything at the GC. Instead the plants that do well have been split and repeated around the garden which works well.
I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
It's the go with what you've got principle, isn't it @GardenerSuze Much less stress. Fighting nature is a bore and I suspect it isn't particularly eco friendly either 😉
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I would stick with no-dig. However, sometimes to kick start the 'no-dig process' its necessary to dig in really large amounts organic material - often just once is enough - then keep placing on the surface after that. I use manure & coarse garden compost.
I have a damp garden with silt and clay subsoil - it's taken a while to improve my soil texture (5 years) - but it's still a damp garden. I quite enjoy planting it with things that enjoy the conditions. The small veg garden is in raised bends 2 sleepers high but even they stay quite damp. I can grow most things - carrots or parsnips not so much but things like peas & French beans do OK.
I don't think,even in my enthusiastic youth, I would have tried to do it all at once.
To avoid the problem @GardenerSuze mentions of plant roots hitting a solid layer of clay, I broke up the hard pan, removed loads of large stones and dug in the premixed new material to this base layer, then returned barrowfuls of the clay soil and forked and mixed in a greater quantity of new material, then added a thick layer of composted bark on top as a mulch. So the bottom layer has a higher clay content than the top but the transition was gradual and it was well mixed in to a plantable depth. By the time plant roots hit the base layer, it was not as hostile as it might have been and they were strong enough to penetrate it.
All this basically meant my soil was workable many years faster that if ‘left to the (nonexistent) worms’ but you do need, literally, tonnes of manure and compost 😊
Much less stress. Fighting nature is a bore and I suspect it isn't particularly eco friendly either 😉