adding chalk to clay?

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penny
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adding chalk to clay?

Postby penny » Tue Mar 18, 2008 4:03 pm

Hi, my husband is a builder and he has just had to dig up large quantities of chalk from a site. I garden on heavy clay so I wondered about just speading some on top as a sort of mulch. What do you guys think. Transportation not that easy but not impossible. My view not his! Penny
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oldherbaceous
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Postby oldherbaceous » Tue Mar 18, 2008 7:18 pm

Dear Penny, i suppose it depends on what you are trying to achieve by adding chalk.
It would probably raise the P.h level, but i think it might make your clay even stickier.
You really need plenty of bulky manure or compost.

Sounds as if you should have married a farmer and not a builder. :wink:
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penny
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Postby penny » Wed Mar 19, 2008 8:17 am

fair comment! penny
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richard p
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Postby richard p » Wed Mar 19, 2008 9:10 am

your time would be better spent adding manure or compost, they are well proven. maybe the chalk would make some paths.
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Postby Johnboy » Wed Mar 19, 2008 10:09 am

Hi Penny,
They used to construct walls with the two ingredients you mention. I suspect that to add lime to clay could very well make the soil almost unworkable. What Richard has said is the way to lighten your clay. I would add to that that sharp sand is very good at breaking up clay. If you husband in the course of his work can get hold of Sharp Sand but not Builders Sand as this does the same that lime would do.
JB.
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Postby PAULW » Wed Mar 19, 2008 2:22 pm

PENNY
This is a brilliant idea, if dug in properly with compost and gravel it will help drainage, the clay has a positive charge that holds on to the water and the chalk has a negative charge lets go of the water, did this at college in soil science but cannot put my hand on my books at the moment or remember what the process is called.
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Postby Johnboy » Wed Mar 19, 2008 5:24 pm

Hi Paul,
The question begs, drain to where? Then with the water drained what then? I too did soil sciences and it is perfectly true what you say but I am afraid it goes a great deal further than you a looking.
JB.


On this site you will see a demonstration of what I mean.
www.ajgoodeconservation.co.uk/conservation.html
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richard p
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Postby richard p » Wed Mar 19, 2008 6:08 pm

for chalk to be of any benefit it would have to be in a powder form. i would hazzard a guess that any a builder has dug out of a foundation is in the form of rocks and of absolutly no use horticulturally.
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penny
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Postby penny » Thu Mar 20, 2008 7:36 am

thanks to all, was in fact quite fine but now back in the skip, extra bickies and coffee to cheer up long suffering builders.
Today's excitement some spare turf!
Penny
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Re: adding chalk to clay?

Postby pesco » Wed Jan 12, 2022 11:37 am

Hi,
I was lucky enough to have very heavy clay in my garden. Some 20-30cm below the surface it was yellow/orange, good for making pottery and not for gardening. Now I have beautiful clay-loam, loose, airy and very fertile. Some 50-60 cm depth of it last time I checked. Its probably around 80-90 cm down today.

Lets start with pointing what not to do. Sadly i can see lots of very bad advise. Damaging really.
Never add sand or gravel to clay !
It will form sort of concrete. Pretty much unworkable.
Clay particles surround grains of sand/gravel and texture wont change. The sand/gravel will just make it more difficult to put nything down into the soil.
Do an experiment to see yourself the mechanics. Take a glass of flour - as you can see not much air in between the particles. Then take a glass of peas - you can see lots of air. Now take a glass of flour and handful of peas to it - result, peas will mix, resulting in flour filling all the voids between the peas and still no air pockets!
Same goes with clay and sand/gravel with added hindrance of sand/gravel making more difficult to put anything down into the sail as mentioned above.

I do not know if ground chalk will loosen the clay up or not. Meant to do an experiment long time ago, but haven't come around to do that yet.
As per opinion above about the "chalk boulders being unusable" - it is very soft rock and it doesn't take much to beak it down or powderise. Strong, preferably metal, bucket, some metal bar, preferably wide and few minutes of pondering in the bucket will turn the chalk into a powder.

Best way, to break it up - three ingredients, organic matter and charcoal (once "charged with biology it is often called biochar), plants.

Organic matter should be dug in, the finer the better. Saw dust is great, The more the better.
At the same time dug in lots of ground charcoal.
The charcoal should be powderized. Again, bucket and metal/hard wood bar. Make sure that the charcoal is moist so you don't generate cloud of dust which is not very good for health when breath in.
You can dug in bigger chunks, but the smaller the charcoal particles the more effective it is at breaking up clay.

Organic matter will break down over time and has to be replenished, but no dig is needed. Actually any digging is damaging to the soil.
Charcoal will stay in soil for years (dozens?hundreds?) doing its magic.

I could write a book on benefits of charcoal in the soil, here enough to say that it is single best soil amendment known to man kind.

Once you dig in the stuff above you can plant your veggies.
At the harvest remember to never pull out the roots. Of course if the root is not your crop - cucumbers, tomato, lettuce etc. Leave the roots in the soil, so they can rot providing organic matter in the soil. This organic matter is not fertilizer. It is food for soil microbes which fertilize your plants. Any spare space in between your veggies use to sow some stuff to chop later on. Plants like wheat, rye, rape, mustard. Point is that these plants grow and spreading roots down in the soil. Once chopped at surface level they will not regrow from roots. Instead the roots till rot adding organic matter to the soil. The top dump into the compost.
And that is it. No more needs to be done and you will enjoy beautiful, fertile clay-loam.
Never dig the patch again. Just add few cm of compost on top every now and then when planting/sawing new veggies.
Never fertilize, never use pesticides.
Healthy population of microbes in the soil will provide all the nutrients your plants need. Digging up, fertilizing, using pesticides kills off the good guys in the soil and do more harm to you plants than help. Once good guys are killed off, the bad guys have space to thrive.

Very beneficial is to inoculating the patch with fungi - like parasol mushroom, portobello mushroom etc. Not only they will assist your plants with gathering nutrients, break down organic matter in the soil, but as a bonus you can enjoy very tasty mushroom every now and then :)

The only exception when you need to dig up the patch is when you want to grow early succession plants like brassicas.

The above is just a top an iceberg. If you want to know more search online for "no dig method" or "soil food web".

Enjoy :D
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