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composting seaweed and sugarcane left overs

 
Posts: 9
Location: East Africa
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At certain times of year I have plentiful supplies of seaweed. Wondering where I can find  enough browns. There are quite a few sugarcane juice places around with all their bagasse. Does anyone have experience mixing these two? Should they make good compost? What proportions would I use?
Thanks!
 
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I would add at least 2parts sugarcane residue to every part seaweed. But you can always go crazy with the sugarcane residue.
Really, I would cover the entire farm with 10inches of sugarcane residue. In addition to setting aside 10% of the farm to composting huge piles of sugarcane+seaweed. If possible I would make a ton of biochar.

Don't forget to activate your soil with water kefir+worm compost tea+milk kefir(or any type of milk fermentation including wild). Add all 3 with a handful of healthy soil and aerate it to multiply these good microbes then spray them on everything (soil/compost/leaves/etc). I would recommend doing it once a month.
 
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Cath,

I checked your profile to see where you are at.  I am not entirely certain what you have available in East Africa, but I will try to give you a few suggestions.  First off, congratulations on getting seaweed.  This is right at the top if not the very top of the list of best greens to compost!

Fallen leaves are one of my favorite compost items.  In fall around me they are an abundant source of browns with added nutrients.  However, I have no idea if you get a “leaf” season like I do.  If f leaves are not available, I would try straw.  You could buy some, or get some old straw from someone, but that would also likely be boxed with greens already.  Hopefully you already have some old garden residue and if this is dried, it also likely falls in the brown category.  Finally, should none of those work, I would suggest getting some wood chips or maybe peat moss.

Note, all of these brown suggestions are only if the baggasse does not work, but I think it will make fine brown material for you.  I would think that about 5-10 to one (Browns to greens s) would work.  This might be a bit on the green side, but is worth as a starting point.  Make sure everything is chopped up and mixed thoroughly.  Keep moist but not soaking wet.  If it does not heat up, try adding greens.  If it starts to stink, add browns.

Good luck and let us know how this works out.

Eric
 
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I use the bagasse as a mulch, it is fabulous. When I compost sugarcane bagasse is one of the only sources of browns I have (no deciduous leaves, hay costs too much-- my other options are sawdust and shredded paper). It works okay, but since I have so many greens I end up with a huge pile (and I need to truck in the cane, it's a PITA), so I do rabbits/bokashi in the summer and only compost in the winter, when my tiny farm has more space available.
 
Cath Johnstone
Posts: 9
Location: East Africa
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Hi
Thanks for your replies. Other questions...
Is the sugarcane residue already classed as brown straight after the juice has been pressed out, or would I need to leave it in the sun to dry?
I can also get hold of coconut fibre, the stuff that comes out of the middle between the inner and outer shells. I guess this is very high in C and would be another option for my browns?
Really so much of the browns? Is this because the seaweed is so high in nitrogen? It's the seaweed that I have the almost limitless supplies of just now, and the browns that are more of a limiting factor....:0 So my leaves will go first to the seaweed, then to the leaf mould
Thanks again.
 
Eric Hanson
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Cath,

I wish I had the supply of seaweed you do.  It is some truly wonderful stuff!  Generally, yes, browns need to dominate a compost pile.  I wish I had your supply of greens for all of my browns.

However, since you do have this almost unlimited supply of seaweed, there is no reason you can't make use of that as well.  If you have a garden or some trees, I would be tempted to lay down the seaweed as a sort of mulch right alongside the plants.  It will still decay and send its bounty into the ground and thence into the plant.  Personally, I occasionally get huge supplies of grass clippings in the spring--more clippings than I can combine with my available supply of browns.  I have made 5' tall piles of just grass clippings and let those break down by themselves.  You can do the equivalent with your seaweed (only better because it is seaweed).

Best of luck and let us know how it is going,

Eric
 
S Bengi
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Sugarcane left overs have a C:N ratio of 50:1 similar to cornstalk and leaves in general, we could given call it similar to wheat straw to simplify stuff.
I wasn't able to find out the C:N ratio of seaweed. But I would just treat it like any other green aka C:N ratio of 15:1

I did find some research that said 4 seaweed to 1 sugarcane works best for max growth.
https://www.researchgate.net/publication/275524578_Seaweed_compost_for_agricultural_crop_production

Upon further googling seaweed has a C:N ratio of 10:1
https://ucanr.edu/sites/mginyomono/files/170818.pdf

Two seaweed + One Sugarcane leftover
[10+10+50]/3
[20+50]/3
70/3 = 23
23:1
That is pretty close to the 25:1 ratio for perfect compost.

One Seaweed to One Sugarcan leftover
[10+50]/2
60/2
30:1

Four Seaweed to One Sugarcane leftover
[40+50]/5
90/5
18:1

One Seaweed to Five Sugarcane leftover
[10+50+50+50+50+50]/6
260/6
43:1
It hardly moved from the 50:1 for straight sugarcane leftover.
CN-ratio.png
[Thumbnail for CN-ratio.png]
 
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Cath Johnstone wrote:Hi
Thanks for your replies. Other questions...
Is the sugarcane residue already classed as brown straight after the juice has been pressed out, or would I need to leave it in the sun to dry?
I can also get hold of coconut fibre, the stuff that comes out of the middle between the inner and outer shells. I guess this is very high in C and would be another option for my browns?
Really so much of the browns? Is this because the seaweed is so high in nitrogen? It's the seaweed that I have the almost limitless supplies of just now, and the browns that are more of a limiting factor....:0 So my leaves will go first to the seaweed, then to the leaf mould
Thanks again.



OUTSTANDING! fresh squeezed sugarcane is a green (cane is a grass) so the dryer it is the more you can count it as a brown.
The coconut coir (fiber you mention) is always a brown and it will work great with fungi  mycelium.
Seaweed can be dried before using and in that state it is a brown, fresh it is a green.

In your area of the world I would shoot for a 1 part green for every 10 parts browns, I would also go hunting for some fungi (you can just cut these up and add them anytime you locate some), if you can get some animal dung (any and all types will work) these will bring you bacteria and fungi into the heap.
If you have enough materials to make a "windrow"(a heap that is 4 feet at the base wide, 4 to 6 feet tall in the center and as long as you can make it), this type of heap makes a lot of compost fast and it is easier to handle and work over a bunch of small heaps.

If you can find spoiled milk, that is a great addition as well (anything organic that you don't feed to other animals including humans, can go into a compost heap)

Redhawk
 
S Bengi
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Redhawk why do you recommend 10 browns to 1green for the tropic vs the usual 1brown to 1green for temperature regions

I know that in general the less brown you have the hotter/faster the compost.
The less brown you have the anaerobic/bad the compost is.
One can "never" go wrong with too much brown just super slow but one can easily go wrong with too much green.
I also know that in the tropic carbon does not stay in the soil it is "only" tied up in soil life/biomass.
Did the saltiness of the seaweed and the arid-ness of East Africa make you "limit" the amount of seaweed vs if it was alfalfa hay.

 
Bryant RedHawk
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Since the poster has access to some fairly high nitrogen materials the browns will help keep a heap from starting to smoke in their tropic area.
The salts in the sea weed are mostly good for building hot compost there will be several phosphorus salts along with others and when you add in the nitrogen you can actually get a fire in a compost heap in east Africa.
I have a friend in South Africa that tried using what we in the US would consider a normal mix in a compost heap and within a week he got ready to turn it and it blazed and nearly burnt his face.
Because he told me about that, we started talking about ways to cool his compost heap and he was nice enough to share the notes I suggested he keep on the experiment.
One can always make adjustments to up the heating of a compost pile or to cool it down (as long as it isn't already burning)

Seaweed is fairly awesome stuff but C to N ratios in different species are very different than grasses.
By using what is basically ground up grass stalks (besides sugar cane, bamboo works the same way) you could in theory create a fire bomb when that wasn't your intention. (saw that done by accident once, it burned up a Porsche)

All composting can be considered an experiment, since no two heaps will decay in exactly the same way, even when built side by side at the same time with all the same materials you can find different rates of decay (which is what determines heating).

You gave really good data for all to work from S Bengi but it isn't only about the carbon to Nitrogen ratios, (they are a big part but then you add in bacteria, fungi and all the other microorganisms as variables)
as you also mentioned creating some biochar within the compost, that too is a heat regulator portion.  
 
S Bengi
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Perfect answer I completely forgot about the fire hazard. It is a very real risk, compost easily catch on fire in the tropics. I like your 10 to 1 ratio.

If you go with a thin layer which minimize the the heat loss and moisture loss will increase so that will help.

I think that having more uncomposted carbon in compost is better for building soil in temperate regions. So having too much brown is okay, even pure woodchip (400:1 C:N ration) that is 8inch deep is wonderful in temperate regions.

I know that just putting down only sugarcane mudpress/leftover is an improvement over nothing. And having 2 seaweed to 1 sugarcane leftover gives the best 1 time growth after application. I am not too sure what is best for long term soil building (increased carbon in the soil) in the tropics other that biochar and biomass(soil life/mycelium).

I will have to read up and experiment with it.


 
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