Wednesday, January 7, 2009

a note about citrus

after a little bit of investigation i believe i have found some useful solutions for the vexed question of how (and if) to compost citrus.
this is something i have been asked more than once. and i've had my fair share of grief seeing orange and lemon peel add to the slush i am attempting to remediate in my own bin right now. yes, it is acidic and the worms do not like it. and, according to Paul Stamet, there is no fungi that breaks down the volatile oils, which apparently are as much of a problem as is the acidity. after all, it is the orange oil that is used as the antiseptic agent in many of the "green" cleaners to cut grease and kill living things.
however, there are other uses. you can dry the peel and use it as fuel,
in this case there's even a commercial application. not only does the dried peel burn well, but it gives off a great aroma. you can freeze the peel and then compost it. apparently it breaks down much faster, and the freezer smells great. however the following three stage juice pulp composting recipe - from the Permaculture Discussion Forum - takes the cake for the most innovative solution:

Re: Composting citrus?
by Ichsani » Sun Sep 21, 2008 1:42 pm
Hi all
After my first attempts at juice pulp composting ended in rank, pongy failure
I hit upon a recipe that worked- found through lots (did I say lots?) of trial and error-

1 part pulp (citrus mainly, some vege and other fruits)
1 part coffee grounds a couple of handfuls of rich soil/old compost/ leaf litter etc
some token handfuls of lime (for later)
lots of microbes and wormies (free!)
the luck of the compost faeries (with us all)

I used a three stage process - involved, but it worked better than anything else I tried.
Stage 1:
The pulp and coffee came in garbage bags when I got them - either way, mix the pulp, coffee and those handfuls of soil in one bag (it really doesn't work without this step - the coffee has effectively been heat sterilised and the pulp doesn't have many microbes in it - cause the inside of the fruit doesn't - or shouldn't. When I mixed bags without the soil/old compost added, the coffee/pulp 'mummified' and didn't break down for yonks).
Don't add any water - just the pulp, coffee and soil/old compost innoculent.

The bags can't be so full else they'll tear. After mixing twist the bag shut so there's little air and turn over so its doesn't come undone - you can stack up several bags this way. Leave in a shady spot for at least a few weeks (no sun, not even a bit - another lesson learnt).

Stage 2:
When you have enough to make a pile (mine were ~1/2 cubic metre) slice open the bags - they'll be a little whiffy but only slightly. Its not a 'knock you over' kind of pong. The coffee bits look more 'fluffy' and the pulp looks pretty much the same but the smell is 'different' to when it went in ..... don't put it on plants 'to finish off in the garden' at this stage - it'll kill seedlings and such as there is a bit of alcohol produced.

Make the pile as big as you can comfortably turn (or use one of those tumbler things for bigger jobs). I did mine in compost bays open onto the ground (this helps for stage 3).

For each bag you add, chunk in a handful of lime (its nowhere near enough lime to neutralise the acidity of the citric acid 'in theory' BUT the theory strictly only holds for an acid and an alkali by themselves....and can't account for the diversity of molecules that make up the pulp and coffee, the wonders of life, microbial succession and all that guff.
Mix the pile around and sprinkle with water - moist not sodden is the aim.
You can add some leaves or straw at this point to make the finished compost less dense but try without first then adapt the mix how you see fit next time.

Fork it around a few times a week, sprinkle with water to keep it moist. It'll get HOT after each forking. This went for about 4 weeks depending on the season and the number of times I turned it. When the pulp doesn't look like pulp any more and it doesn't really get hot after turning, its time for:

Stage 3:
Either move to a finishing bay or leave in the same spot to 'finish' out of the sun. No more forking just let the worms move in. This stage takes about 4 - 8 weeks depending on the season - shorter if its warm. It also helps to cover the pile with hessian, old felt, leaves or something to keep it humid. Leave it alone except for a bit of water now and again.

That's it.

This made perhaps the best compost I have ever produced. Rich, very dark, very sticky and very very dense. It smelt wonderfully earthy and was so densely humusy that I reckon you could have modelled figurines out of it. My 1/2 cubic metre piles became about 20 buckets worth each - less than a 1/3 of the original size.

I had to cut it 70:30 (crappy sandy soil: compost) to use it. Other, more crumbly composts I grow straight into no problem - but not this one. I tried higher amounts of this compost in pots but it dried very hard and shrunk by about 1/3 and would only wet up if submerged in a bucket - hardcore compost!

If leaves, straw etc are added at stage 2 the compost comes out more fluffy and only needs a 50:50 cut.

Out of my own curiosity I tested the pH through the stages - end of stage 1 pH ~ 4, end of stage 2 pH ~ 6-7, end of stage 3 pH about 7-9. More often it was about pH 8. After cutting with (formerly) crappy sandy soil pH was ~7. Perfect.

Like everybody else here - I would rather all that organic matter goes to making us more gardens!!!!! (rather than going to landfill to make methane to warm our toes).

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