Compost bin/Worm farm in a bath tub.

ClissAT

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My compost bin is working really well & I am harvesting compost for my container garden top ups already.
So far I am not harvesting worms although I'm sure there are some ending up in the compost I take out.
They are working really hard turning litres of F&V scraps into compost in a matter of days.

I started with the bath tub sitting up on 2 stacks of free old pavers to bring it up to my waist height so I didn't have to bend over. I half filled the tub with course cane mulch (from a bale not the stuff used to mulch pot plants & small garden beds).

I seeded it with the last of the compost from my Mothers raised garden bed & compost bin which was thick with worms. Then added some bags of goat manure & various green waste from the garden. The tub still has it's drain pipe plughole so rodents cant get in that way but by placing a container under it, I harvest off the juices to pour onto my tomatoes which are growing in an adjacent bath tub.

About every second day I add around 2-3lt household fruit & veg scraps (not chopped or put in the blender). I don't add all the other household organic materials that other people add like vacuum bag waste, etc...YUK!
I don't add heaps of paper although I will add a few sheets of used kitchen paper sometimes. Once a week I sprinkle on the dried & crushed egg shells from previous weeks cooking.
I mix the fresh scraps into the next portion of the old compost. So I am making my way from one end of the tub to the other progressively. It takes me around 6wks to work my way along & back to the beginning.

Then to make room for the next round, I take out the oldest compost which works out to be about half the length of the tub but I leave some in the bottom ontop of the old cane mulch filler which is where the worms live.

This gives me the room to begin adding all the new scraps. Each batch of scraps is mixed into the remains of the old compost in the bottom of the tub. I top up with a bit of blood & bone & some green or brown garden waste depending on what the compost needs to keep it in good health. Once a month I am adding a thick layer of goat manure which the worms go crazy for & turn into the lower compost layers overnight. Over that is course cane mulch or dead garden waste as an insulation layer.

Once I get the half of the tub filled it is time to take out the second half of the tub of compost left from the last round of filling. The worms mostly live in the bottom layer of cane mulch which is nicely moist.

After I started making the compost I soon found rats moved into the nutritious feeding resource. So I had to make a heavy wire lid that fitted neatly inside the rim of the bath tub. These photos below is the result. There is a sheet of corrugated iron as a rain cover but allows good air flow.

I made the lid out of scraps of verandah flooring. It is a fairly heavy untreated old hardwood that is dressed all around & painted with a stain & weatherproofing.

I used my old shade house potting table which was around the right size to square up a template on, so my lid would fit properly into the top of the tub. Luckily I have a big old steel workers metal square so the process was easy.

I used 10mm square wire netting which I also know of as Budgie or Bird Cage Wire. It came in 60cm wide rolls & I had a few scrap pieces which I just overlapped rather than cut when I screwed it to the under side of the lid frame.

All screw holes had to be clamped, predrilled & countersunk to prevent cracking of the wood. I was lucky enough to find screws just the right length so their sharp little points didn't stick out the under side.

compost bin rodent lid.jpg


compost bin & rodent exclusion lid.jpg
 

ClissAT

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Looks good Clissa, does it work ok?
I'm wondering, most compost bins we see are sealed, covered or closed in. I assume to retain moisture.


Yes Stevo it does work remarkably well.

The tub is up off the ground so air moves under it cooling it somewhat & the plug hole still has its fitting so nothing other than ants can get up the pipe into the compost but it lets out any excess moisture which drips into a bucket.

On top of the compost I have 2 layers of hay, the first is fine aged & crisp lucerne straight off old bales left out in the sun that crumbles to very fine fragments which the worms love & the second is a layer of very course dead leaves. The only purpose for the leaves is to exclude some light & insulate the top of the compost from the radiated heat off the sheet of corrugated iron I use as a lid. If I used a lid made from some insulated refrigeration panel for example, I wouldn't need that second layer but I wouldn't have such easy air flow enabled by the corrugations.

In summer I may find there is too much heat coming off that iron so I will have to cover the iron with hessian bags or other such material but not down the sides which would prevent the air flow under the iron across the top of the compost.

In my experience it is the sealing off of the compost using bags that can cause it to go sour. It needs to breathe. The bags placed immediately in top of the compost are supposed to allow it to breathe but often that doesn't happen enough.

Yesterday I took out 10lt compost but because there were so many worms, I struggled to get them to move elsewhere in the tub. I didn't want so many worms in the compost I used to plant a tree. These are compost worms not ordinary earth worms so they'll die once their ready source of food is eaten. Better that they stay in the good stuff.

There is a process of baiting them to move along in the tub by clearing the surface of the area you want to harvest from, then placing fresh 'food' in another place to get the worms to move away from the compost you want to harvest.

However, I think mine has already reached a point where I have to duplicate the system & hive off half the worms because there are just too many worms in the given volume of the tub. Also I need to fluff up the bottom layer where the cane mulch was because new cane mulch needs to be added before summer to allow better drainage & living conditions for the worms. Its during that process that hiving off is easiest.

But I really don't need 2 complete worm farms. Anyone want half my worms?:idea:
 

Ash

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That's a lot of worms! Just doing it with one small worm farm and it's enough for us to manage feeding them and watering them. What a set up you've got!
 

ClissAT

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That's a lot of worms! Just doing it with one small worm farm and it's enough for us to manage feeding them and watering them. What a set up you've got!


thanks Ash :D

I harvested off another 20lt of compost on Thursday last, then replaced new cane mulch in the bottom of a third of the length of the tub before placing the worms back ontop of that mulch ready for a new round of scraps. They seem happy enough with that setup!:)
 

ClissAT

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Just wanted to update regarding the worms.
They just keep multiplying! There are so many they have formed knots.
But slaters have moved in too which I really don't need.
They form a thick grey carpet over the top of the compost right under the hay layer which they are feeding off.
They do a fine job of breaking down the dry hay but I would rather they not be in there as they munch on seedlings I plant in the garden using the compost.
The tub come through a heavy wet season with no ill affect on the contents. The iron doesn't cover right to the edges but by making sure the bottom has a thick layer of course cane mulch, there is plenty of drainage. So I got a lot of worm tea.
I have a pair of very fat geckos living in the top of the compost too. They scurry away each time I lift the lid. I guess they are feeding on the never ending supply of slaters.
I do have saw fly lava in there now too. Just moved in. Maybe they will vacate once the wet season is over & the worm farm dries out a little.
I'm still harvesting heaps of compost from the tub. I often have trouble creating enough kitchen scraps so have to cut stuff from the overgrown beds to feed them.
 

Letsgokate

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With the sawfly I had them in one of my worm farms. Had to ease back of food a bit and added more dry stuff, paper etc, picked out as many as I could by hand. Then for a few days in a row with no other fruit and veggie leftovers in there I put in a slice of bread. The larvae go all over the bread, then it can be lifted out and given to your chooks. Worked a treat
 

ClissAT

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The thing is with saw fly, that they actually do a really good job of eating the food & turning it into good compost a lot faster than the worms.
They just look horrible in there & are indicators that the compost is verging on too wet.
 

Letsgokate

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I think it depends on if it’s a worm farm of compost bins. As a straight worm farm where I had the issues is worms don’t mind a few sawfly but not a lot. So I had to reduce numbers. I did think I now know how to breed sawfly though and when I get chooks again I’ll be setting up a sawfly farm
 

DarrenP

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That's a great compost bin, ClissAT. And I think you should patent that lid. You could make a fortune.
 

ClissAT

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That's a great compost bin, ClissAT. And I think you should patent that lid. You could make a fortune.

LOL yes, but its not saw fly proof!! :D

The saw flies came after I put fat off steak in the compost.
I have another bath tub that I put camping toilet dry contents into.
That 'compost' goes around the fruit trees & it occasionally gets saw flies in it too.
I used the same worms & they are thriving in there as well.
At least I can do something right!
 

PeteEakle

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Geoff Lawton did a great video where he describes a similar worm composting design:
 

Lucas

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Hi Clissa
Does the Compost dry out with the mesh lid?
Looks great have a couple of old baths might just have to try it
Cheers Lucas
 
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