compost proportion calcuator

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compost proportion calcuator

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James

Joined: 11 Jan 2006
Posts: 2866
Location: York

Posted: Tue Apr 08, 08 2:01 pm Post subject: compost proportion calcuator
just found a handy website that calculates what proportions of carbon & nitrogen stuff to mix up for optimum composting: https://www.klickitatcounty.org/solidwaste/fileshtml/organics/compostCalc.htm Interestingly, you need almost equal quantities of loose grass clipings and newspaper to create an optimum C:N balanced compost, but you need much less cardboard for the same result.

Azura Skye

Joined: 14 Jun 2005
Posts: 2199
Location: Carmarthenshire

Posted: Tue Apr 08, 08 2:10 pm Post subject:
I thought it was 10:1 Carbon nitrogen?

Azura Skye

Joined: 14 Jun 2005
Posts: 2199
Location: Carmarthenshire

Posted: Tue Apr 08, 08 2:12 pm Post subject:
just realised how that webbie works : D haha tis good i meant - i thought 10:1 was the ideal ratio, good to see what other stuff contains : )

Rob R

Joined: 28 Oct 2004
Posts: 31902
Location: York

Posted: Tue Apr 08, 08 2:17 pm Post subject:

Azura Skye wrote:

i meant - i thought 10:1 was the ideal ratio, good to see what other stuff contains : )

If only, would make life so much easier

gil
Downsizer Moderator

Joined: 08 Jun 2005
Posts: 18420

Posted: Tue Apr 08, 08 3:40 pm Post subject:

Useful site. Thanks, James.

I put both of my main compost mixes through their calculator and was pleased to see they both deliver a ratio of 25-30:1

Mix A (the general compost heaps)

Fruit waste 4 parts
Veg waste 1 part
Cardboard 0.5 parts
Office paper / newspaper 0.5 parts

Mix B (composted livestock wastes)

Slat muck (beef cattle) : 1 part
Strawy muck (straw, but with muck in) : 1.5 - 2 parts

However, B is much faster than A (4-5mths vs 1 yr)
I don't turn either pile (sheer laziness/lack of time)

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Tue Apr 08, 08 5:20 pm Post subject:

Excellent link. (Because nobody else had added it to the site links page, I have!)

Note BTW that the ingredients list is in "green-ness order", the 'greenest' at the top, the 'brownest' at the bottom - colour isn't always a good guide!

That calculator is also extremely helpful in regognising the difference between proportions by volume and by weight.
Its a useful exercise to play with the numbers to see just how much volume of straw needs to be added to pure pigshit ("swine manure") to bring it into fast composting range. (I get the straw volume needing to be 5 and a quarter times the volume of pigshit to get 25:1 - and almost 10x the *volume* to hit 30:1. It takes a *lot* of straw!)
Of course, one other thing that does determine how fast the pile rots is how finely chopped and well mixed the stuff is...

Rob R

Joined: 28 Oct 2004
Posts: 31902
Location: York

Posted: Tue Apr 08, 08 5:55 pm Post subject:

dougal wrote:

(I get the straw volume needing to be 5 and a quarter times the volume of pigshit to get 25:1 - and almost 10x the *volume* to hit 30:1. It takes a *lot* of straw!)

And I get an 'average' sized bale of straw (4' x 4'd) to be 12.56 Cuft, or 1.25 pig muck to a bale. I think that value (53:1) is a bit off the mark & should be nearer 100:1.

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