# Prep Soil Recipe for 90% Clay Plot - Question on figuring out how much soil I'll need

Discussion in 'Growing Organic Marijuana' started by firstimah, Feb 7, 2009.

1. Ok so a break down, 10 holes, 2'x2'x2' (50 litres), the soil is 90% clay with some really bad top soil a few layers on top of it, so basically it's all going to be removed and replaced as soon as it gets a little warmer out with:

1 cup blood meal
1.5 cups bone meal
1/2 shovel manure
48.816% organic potting soil
29.290% coco coir
19.526% earthworm castings

Ok so the mix looks good, now the problem is, different items come in different packaging, some some will be listed by cu ft, some by pounds, some by litres, some by quarts, etc. So basically what I did was try to find out how much I would need for each of

So for 10 holes these are the numbers I came up with, basically a litre = 4.22675284 these and converting it all into cups. cups, so take 4.22675284 cups * 50 (number of litres per hole) * 10 (number of holes) = 2113 cups. :

10 cups blood meal
15 cups bone meal
5 shovels manure (around 25 cups)
1031.5 cups organic potting soil
618.9 cups coco coir
412.6 cups earthworm castings

So basically from researching all over the place, it really isn't that easy to convert a pound into a cup... I believe it was Fox Farm's web site that said there is 2.77 cups per pound in soil, but almost everywhere else the logic breaks down that there is 16 ounces in a pound and 1 cup in every 8 ounces, so 1 lb would equal 2 cups. My dilemma is that if this is true for 10 holes that 2 cups equals a pound, I'll need around 582lbs of potting soil alone. Since I'm going organic I'm wondering if anyone knows what is more accurate the 2.77 cups/lb or the 2 cups/lb. I'm about to go buy some soil and just scoop it out cup by cup to find out what the number is if nobody can give me a solid answer on this, I just don't want to buy too much when I don't need it. For things like earthworm castings it's different since buying too much of it isn't a bad thing since I'll be using it in teas etc.

Any help, appreciated..

2. Its not really gonna matter if you add 2 cups or 2.77 cups. It doesn't have to be that exact, especially when you are supplementing existing soil. ​

3. But I'm that exact, so to me it matters, I'm not going to use any of the clay in my holes, it'll be at the bottom to support the roots when they get down that far, otherwise it'll just be growing in my soil mix I'll figure it out, just need to remember to keep the receipts

4. 2Â´ X 2Â´ X 2Â´ is 8 cubic feet which is 226.5 litres. Back to the drawing board !!!!

5. Yeah you lost me with all the maths but you're absolutely right, don't add too much meals or manures. Better less than too much. I'm sure you can get the maths. I don't even have cups here. I'll just prepare manures and meals for each hole. And add what's on site and peat.

6. replacing the soil is not very money-conscious in this situation. yes it is the best option but clay soils can be good. they hold lots of nutrients and drain slowly (it didnt rain once all summer in my area). basically you should just add amendments (peat, coco, manures, blood/bone etc.) to the existing soil. you will do MUCH less work but end up with similar results

7. Yea, looking over the mathz, it's going to be much more beneficial to use some of the soil, I'm going to get some 15 gallon pots if I can find them in case it is a really rainy season and I decide to not drop them into the holes. I did the test to see how long it took for water to drain from a hole that size and it took almost an hour. Any other ideas on how to get this hole to drain faster would be appreciated, I dropped some river bed sand in there, but it started to get cold so I went back indoors.

8. ACT (aerated compost teas) has been proven to be a good cure for 'clay soil' - though learning how to brew these teas involves a learning curve, regardless the science is out to know how to break-up these types of soil.

Grow well and grow long.

LumperDawgz

9. #9
Last edited by a moderator: Feb 11, 2009
Clay soils are hard to amend. It's recommended to break the clay in Fall in big clumps, leave it over winter. In Spring, when the clay is not too wet or dry, break those clumps in smaller pieces and mix in the compost and some sand for drainage. The freeze-thaw cycles help it get better. Add dolomite lime (last 3-4 years) in Fall. Avoid a lot of peat with a lot of clay in the hole. The clay will drag your soil mix to the bottom of the hole and kill your plants. Clay is amended with compost and sand mostly.

10. I have not tried it, but I read somewhere that coarse, gritty sand mixes best with clay. I add sand and grit to my mix to improve drainage - roots will not get waterlogged. But I mix it into a peat base, which is easy.

11. Yeah like Cantharis confirmed. Clay is amended with sand, compost + meals, manure. Peat + clay don't marry well (OldPork's experience). Don't do 50 peat/ 50 clay. Using the top soil (first 4-5 inches) from the wild will give you good dirt (look for loam).

12. I went out yesterday because it was beautiful and dug my last hole and I put a little mound in the bottom of it and dumped some river sand in there and it really helped to improve the drainage time from almost an hour to 15 minutes. I believe from reading some posts and forums related to clay soil that the best thing to toss in there to help improve the drainage some more is some coco coir, fairly cheap and effective from what I've read. The sand is free too, right from the river bed, can't beat that.

13. check pH and add pH+ (lime, ashes) 1month before mixing in manures, meals or separate manures, meals from the soil you will modify the pH later.
Nice work Firstimah.
The walls of the hole in the clay soil will retain water so it's good for that. Nice thinking for the mound (thank you Old Pork!!!).

14. Corto

Do you use any humic and/or fulvic acids in your program by any chance?

Just curious - as usual.

LumperDawgz

15. I think they're already in the compost and the manures I'll add next week when I dig. In June-July, I add the peat/sand/clay/worm castings/Op's fish and the plant of course. But some of that magic Japanese bacteria sounds good. The bottled stuff is mostly for indoors that don't have manures and meals. Outdoors is easier imo!!!

16. Corto

Big time! Outdoors is far easier and if it weren't for the amount of rain that we get around here I would definitely opt for an outdoor crop. It doesn't matter with me because I'm a 'legal grower'

Back to the use of humic and fulvic acids, if I could bend your 'cyber ear' and direct you to a web site which will explain why using these products will increase your yields and generally benefit in achieving the healthiest plants that you can.

Here's something to consider - Fulvic Acids

Here's a discussion about humic vs. fulvic acids - Fulvic Acids? Humic Acids? Why use them?

And on a general note I would like to include a link to RemineralizeTheEarth.org which will explain why the use and inclusion of 'rock dust' (known in Europe as 'shattered rock' and other names) in any agriculture project.

I hope you find the information helpful or at least interesting.

Peace

LumperDawgz

17. Wow! Yeah, great information. I'll look it up. I'm playing Mario Kart Wii right now. Ha!Ha!