jeris
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what kind of perlite to amend soil

I have been given advice that I should use perlite to help amend my awful North Carolina clay before I plant my garden. I started looking for perlite on the internet and find there are different variations, from fine to coarse. What should I use to amend my soil?

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Lindsaylew82
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Perlite is not biodegradable. It never goes away. It can also runoff into water systems.

I live in heavy red clay. My garden was amended with 2 large loads of sand and a whole truck load of cotton seed meal about 15 years ago. We have not had drainage issues since.

Sand is a much better alternative IMO. You can also till in all kinds of other roughage. Leaves and pine bark. Anything just to lighten the soil. The more organic biodegradable things you add to your soil, the better your soil becomes!

Happy gardening!

Unless you're potting plants in pots, I wouldn't use perlite...even with pots, I'd use vermiculite. But not in a big garden.

imafan26
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Perlite doesn't work in the ground. Perlite is used in soiless potting mixes. I use 50/50 Peat moss and perlite. It drains well so that plants that get rained on or on daily sprinklers will not rot. Downside, those pots need to be watered daily in summer.

I have red clay soil and I tried to put perlite in a small section. I did not put enough so the clay acted like glue and made perlite concrete.

Ultimately, I just kept adding organic matter. I could not add more than 20% at a time otherwise other bad things happen. And compost needs to be added constantly because it breaks done and sinks. Over time it did make the soil softer, but when it is wet, it is still clay. Coarse sand (builders sand) would be a better choice to add to clay, you still will need a lot. In the end you want to end up with a soil that is 1/3 clay, 1/3 organic matter, 1/3 sand. If you are adding organic matter do not screen the soil or the compost too fine. You actually need some coarser shapes to maintain the air spaces.

Raising the bed will also help with drainage. so if you want a bed about 12 inches deep you would fluff up 4 inches of the clay soil. Make sure the clay is not wet when you work it or you will end up with clods and the soil structure will be ruined. On top of the 4 inches of clay, add 4 inches of sand, and on top of that 4 inches of coarse compost. You can also add 1/4 inch of well composted manure as an option. Till all of that in until it is a homogenous consitency. It is better to double dig it in, but rototiller is faster and easier. Rototilling is not as good because roto tilling looks nice, but is bad for the soil organisms and soil structure and the weight of the rototiller packs the soil down, and you really want to fluff it instead. Most rototillers are designed so you end up having to walk on the ground you just tilled.

Or

You can avoid the clay soil by building a raised bed and sheet compost instead. Over time the composted layers on top will get pulled down into the soil below making it better.

Usually you want to do sheet composting in the fall, but it can be planted sooner if you add 3-4 inches of good soil on the top.
https://extension.oregonstate.edu/lane/s ... osting.pdf

If you have a local composting facility, they may have a garden bed mix that you can get by the truckload. It is cheaper if you have the truck. Then, all you have to do is build a raised bed out of whatever material you have. I use hollow tiles two layers high, dry laid. It is an easy material to obtain and work with. I don't have to worry about chemicals leaching from the lumber or rot, and I don't have have carpentry skills. Just add the soil mix and an irrigation system, fertilizer if needed and once it is watered and settled it should be ready to plant.

toxcrusadr
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Perlite will have no negative effect on surface waters, it's just an inert mineral similar to sand. But I would not use it in the garden either. There are much cheaper alternatives that won't turn your garden soil into polka dots.

Careful with the sand - it's a well known fact that adding some but not enough sand to clay will result in concrete-like conditions in the summer with the clay acting as cement and the sand as aggregate. Actually it's more like mortar mix. You have to add on the order of 25-40% sand by volume. If you are looking to have raised beds anyway, this might work. Just add an equal amount of compost. However, it would be safer to add a soil with a coarser texture than clay but not pure sand, such as a silty or sandy silt topsoil. This way there is less chance of the concrete effect and you get something more like loam, which is roughly equal amounts of clay/silt/sand. Always add compost too.

If you just want to amend the clay, adding compost year after year with decreasing amounts of tilling and digging over the years will result in a nice soil. It takes time but it works.

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rainbowgardener
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If you have a small garden, the easiest thing is to make raised beds and just fill them with good enriched soil. Then your clay doesn't matter so much. Just be sure you punch holes down into your clay (like with a garden fork) before you build the bed on top of it, for drainage.

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applestar
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I’m bumping this thread and would like to continue the discussion about adding sand, perlite, etc. and amending CLAY garden soil —

As already discussed and ably explained by others above, sand is a natural, integral part of the soil aggregate and it’s not necessarily wrong to add sand. It’s generally widely available with some caveats:

- don’t use polymer sand in the garden — this kind of sand is sold alongside other landscaping sands and gravel, and contain artificial additives to set up when moistened with water
- don’t use sand that is known to have been dug up from contaminated land/grounds/sources
- anything else?


I do think there is some kind of misunderstanding going on in the parts of the gardening community about whether to add sand to existing garden soil, especially when there is existing heavy clay. But most gardeners understand that you HAVE to add organic matter. Good garden soil = HUMUS _ sand _ silt _ clay

The way I see it, if I can’t add a whole lot of sand at once, which I can’t due to budgetary and man- (..er.. woman-) power constraints, I can at least add some in small doses along with the massive amounts of organic matter which I am always adding, and work my way up to the golden “loam” ~ “sandy loam” ratio.... :()


If you want to learn more about soil and soil structure, check out these links — the UN FAO one has more illustrations and is intended to teach = easier to understand (at least for me :wink: )
Estimating Soil Texture
Sandy, Loamy, or Clayey?
https://culter.colorado.edu/~kittel/Soil ... andout.pdf
6. Soil Texture
https://www.fao.org/tempref/FI/CDrom/FAO ... 706e06.htm
8B6DC544-CEB4-4084-BF8D-84AB1F257462.jpeg
— this came from —
Training and Learning Center | Sustainable Food Value Chains Knowledge Platform | Food and Agriculture Organization of the United Nations
https://www.fao.org/sustainable-food-val ... center/en/

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

I’m going to go back to the forum archives find links to relevant discussions. I’ll just come back and edit/add to this post when I have the time to search them out, so expect this post to fill out and grow :D

Subject: Please Help Me! Am I doing this right?

Subject: Amending Soil - Reducing Heaviness of Red Clay-ish Soil

Subject: Ok to use river sand.

(this discussion was interesting, but unfortunately the OP didn’t come back, so no follow up results for what was done)
Subject: Soil improvements

(...I should probably stop and take a break ...actually, I’ve been sick in bed for 3 days and I was getting kind of bored.... This next thread really didn’t get anywhere but now I want to try it again — last time I tried was ages ago)
Subject: Soil composition

...if you find others, post them in this thread and I will add them to this post...
...scroll down to bottom of the page and see what the forum’s auto similar topics search has turned up...

imafan26
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If you do use sand, it should be sharp sand not beach sand or play sand. They have different properties and sizes.
Organic matter is still the best thing to add whether your soil is sandy or heavy clay. Organic matter holds moisture, so does clay, so you need to make sure you do not over water. Organic matter has a lot of coarse shapes so it will help fluff the soil. If your soil is saline sodic, adding gypsum will help make the clay easier to dig. There is no real advantage to adding gypsum if your soil is not saline sodic.

Unfortunately, there is no easy fix for clay soil. You will have to continuously add compost every season to get better tilth. Clay is already a weathered soil so it resists change. However, organic matter will continue to breakdown and sink over time. It also helps to avoid tramping in the garden and packing down the soil or working wet soil.

https://extension.oregonstate.edu/news/ ... arden-clay
https://s3.wp.wsu.edu/uploads/sites/403 ... gypsum.pdf



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