Comments on: 18-Day Compost – the Appliance of Science

By: gaby de wilde

gaby de wilde — Mon, 03 Aug 2009 20:53:17 +0000

I’m not expert but I read something about using vegetarian poo. It should work I guess, would it depend much on the diet?

By: Lambchop

Lambchop — Mon, 03 Aug 2009 09:15:53 +0000

What is inexpensive to build or buy, runs on human power, shreds small branches, cardboard, paper, food waste, and leaves? I don’t know, but if you see one, grab it for me!

By: ratbagrob

ratbagrob — Tue, 05 May 2009 12:00:33 +0000

Thank you Paul for taking time in replying and your considered response to my problem.
I am heartily cheered to read that you have not made quality aerobic compost in a plastic bin. Clearly my problem is that I am just not getting the volume large enough to generate the heat and as you say, oxygen is not available. I suspect that this is because the available oxygen in a recently established or turned bin is quickly consumed by the bacteria and then they slow or shut down due to asphyxiation.
I am really pleased to hear an experienced and successful composter state this because I read a great many books and websites on this subject and they are quite flippant about how easy composting is in plastic bins.
I only have one commercial plastic bin as the rest are large plastic pickle barrels with the bases cut off with an angle grinder. I selected these because they were cheap and robust, but also because they were larger than shop-bought bins. They are obviously still too small however and keep out the oxygen.
I will try the wire mesh cage idea, if I can work out a practical base and removable top (because I imagine I will still have to turn it).
I have no reason to believe that I am attracting rats or mice by composting, however I am very conscious of being able to prove to neighbours that rats cannot get into the bin if they should ever complain. (The neighbours, not the rats)
I know that material is very quickly de-natured in a hot pile anyway but I suppose I could continue putting potentially attractive kitchen waste into my rat proof wired plastic bin until it is completely unrecognisable before adding it to the wire cage containing the lawn clippings which give me such grief in the plastic bins.
I feel confident that I can supply enough dry browns to compost the kitchen waste in the bins whilst allowing the wet grass clippings and sundry prunings to get highly oxygenated and “dry out” in the wire cage.
It’s a shame because I believe that the pile would benefit from the inclusion of a range of materials, especially high nitrogen kitchen waste and as you explained, it’s not good to add anearobic material to an aerobic pile. I would love to be on a small holding and not have to worry about neighbours, however I have to deal with this as the great majority of people live in cities and composting is just as necessary in built environs.
I wish I could keep worms because this would solve my kitchen wast problem, but I was a dismal failure when the Summer temperatures became outrageous and it was not fair to the little brutes. They all nicked off.

Thanks again for your interest and response. I will send you a photo when the current batch is finished.
Rob

By: paul taylor

paul taylor — Fri, 01 May 2009 00:31:51 +0000

Hello ‘Rob the Rat’,

Great to hear that other people have been making compost for 20 years or more! When you talk about having ‘stagnating piles’ this to me means that they are smelly and hence anaerobic. The thing that you need to look out for when you mix aerobic with anaerobic compost is that anaerobic bacteria eat highly beneficial aerobic fungi which is the hardest thing to actually grow properly I compost and the hardest thing to re-establish in soils. When you have a ‘stagnating pile’ what I would do is mix it in with some larger particle material such as wood chips which would get the air back into it and then use it after a couple of weeks to make a new compost pile. A compost pile should not go anaerobic simply because it is hot outside, it goes anaerobic because it cannot diffuse oxygen because it is either too wet or the particles that you used initially were too small. It can easily go anaerobic if it is covered with plastic during the heat so if you are going to cover it with something to keep the moisture in make sure that there is a 200mm air space between the plastic and the compost pile and that the plastic is not held down so tightly so that air cannot get under it. Remember, we are making inoculum compost which is aerobic and more than 50% living organisms. This is not just ‘decomposed organic matter’ (which is OK as a garden food but does not revitalise degraded soils).

I have never been able to successfully make quality aerobic compost in a plastic bin. I suggest that you make a circle out of fine wire mesh and use that as your compost container. That way the oxygen will be able to diffuse into the pile and it will not overheat. As temperature goes up the ability for air or water to hold oxygen drops. If your compost stinks it is not beneficial to your plants as it is anaerobic. Even if it gives you plant growth it is at a cost of soil health.

Feel free to send me a photo of your compost and I’ll send you a photo of what we make paul@trustnature.com.au. Also see trustnature.com.au.

Regards, Paul Taylor

By: ratbagrob

ratbagrob — Thu, 30 Apr 2009 12:17:38 +0000

I really appreciate the information provided above, especially the knowledge of chemistry and biology in which I am woefully inadequate.
I live in Adelaide and have been composting for 20 years plus. Sometimes I make excellent compost and sometimes I end up with a stagnating pile (after the initial tremendous heat in the first three or four days). I find that I have to distribute the stagnated pile amongst new batches. I suspect that this might be a very naughty thing to do but I have to do something to finish it off.
I also suspect that the wonderful rich, crumbly, moist, dark compost we see in books and television shows which looks like commercial seed raising mix, might, in fact, be commercial seed raising mix.
After scores of batches, I have yet to find that all elements are unrecognizable at the end, even after leaving batches to go anearobic for a month or two after the initial aerobic cycle with frequent turning. Similarly, whilst I use a petrol powered chipper to smash things as small as possible, it is always very twiggy. I have to sieve off finings for the same effect as the commercial pictures of compost and this is not practical for the entirety.
My biggest issue is water. To eliminate vermin, I have to use bins with galvanised wire mesh bottoms (10 mm by 10 mm) and I think this stops me having the recommended bulk of 1 cubic metre. I never add moisture as the kitchen scraps are just so wet, as are the lawn clippings. I mulch phone books, straw and woody parts of shrubs to kind of add more “dry brown” but it is never enough.
I know it is again naughty but the reality for city / metropolitan people is that you do have to keep adding to a pile daily. There is just no way to store kitchen waste long enough to start a single pile periodically. No matter what the books say, it does start to smell even though you have a lid on a bin.
I have tried to squeeze the moisture from kitchen waste prior to adding it to the bins but they just get too wet.
I have even tried to drain off the evaporating water collecting on the lids of the bins with zero success.
I think that I need a ton of (dry)animal poo periodically but this defeats the purpose of trying to have a circulating nutrient system with little external input apart from the kitchen scraps which often contain shop bought material.
Don’t get me wrong. Even if a composting effort is only half successful, we have still added nutrient to and improved soil and we have reduced the “crime” of throwing nutrient into land fill.
I will just try to keep having a go, adding as many different ingredients as I can lay my hands on and keep trying until, by trial and error, I get it right.
One tip I can give is to even out your input by storing dry browns if you can. For example in Autumn, I have a wonderful supply of fallen leaves and whenever I cut the lawn, I have three barrow loads of grass. In order to use them and stop them from clogging the pile, I have to add dry chipped plant material, shredded cardboard and dried grass I have laid out in Summer. This does take a lot of space in my garden shed however and is a real fire risk in 40+ degree Summers.
Oh, another thing, hedge clippings are great for heat and aeration and the clippings from lavender are brilliant for making it burn like a fire and smell fantastic!

By: paul taylor

paul taylor — Fri, 06 Mar 2009 07:10:36 +0000

Compost is not a mystery, it once was a talent gained by experience, now it is a science, think of compost as a living organism as “good compost” is more than 50% living organisms. Compost for “compost tea” is not anaerobic and is not dominated by actinobacteria.

In my experience (working commercially with compost and compost tea), it is difficult to make fungal dominated compost in 18 days, even with proper monitoring and turning, the reason for this is that bacteria dominate during the initial process and once the simple foods are broken down and ingested by the bacteria, it then takes time for the fungi to colonize and establish. I find that too much turning disturbs the establishment of fungi, if you are going to make “18 day” compost, it would be good to add some carbohydrate(oat flour) to the pile at day 18 and leave the pile for an additional 2 weeks without turning to allow time for the fungi to establish. I find that it takes me about 8 weeks to make a good fungal compost by hand (I turn when it is about 65C using a 36″ compost temp probe).

I know several people that make “quick compost” and that seems fine for vegi gardens and is great for breaking down waste in a hurry when needed, I have never seen a ‘Quick compost” have the adequate diversity for making good compost tea.

Be very careful with anything anaerobic (looks wet, smells bad), it is anaerobic if it is dominated by actino, one of the major issues is that anaerobic bacteria love to eat beneficial fungi, when a compost tea goes anaerobic and you examine it under a microscope, it is literally covered with anaerobic bacteria (if you would like a photo of this email paul@trustnature.com.au), within 24 hours after the tea is made, there are no fungi left in the sample (this is also a concern with manure teas that are often anaerobic because of a lot of misunderstanding). Beneficial fungi are responsible for soil structure, soil pH, ambient moisture, and for the mineralization of the soil, the most difficult thing to re-establish in degraded soils is beneficial fungi, so be careful.

Compost for making “inoculum” for compost tea, is an aerobic process, we use about 45% carbon (not too fine half of the C as wood chips works well), about 35% “green waste and the balance manure, legumes, lucerne, etc. One of the principles that I have discovered is that “diversity of materials supports diversity of microbes”. The key to “inoculum” compost for compost tea is to get a massive diversity of beneficial microbes. And as Dr. Elaine Ingham (Queen of the science of compost tea) might say, we are not making “decomposed organic matter” we are making aerobic, thermal compost, it must be monitored by temperature and by moisture. Once the compost gets to about 65C we begin to get lower O2 conditions and we begin to lose diversity of beneficial microbes, we also begin to gas off valuable nutrients.

When first building a compost pile, we usually place about 150 mm of wood-chips on the ground first and the build up the compost pile on top of this, this will help to ensure that the diffusion of O2 is adequate during the process as O2 can diffuse not just through the sides of the pile but from the bottom as well.

Compost tea is also a highly misunderstood process, it must be aerobic, “compost tea brewers” are powered by air pumps, not by water pumps and it is not made successfully in water that is not aerated.
The importance of Actively Aerated Compost Tea” (soilfoodweb.com.au) is that is is aerated with an air pump, the air is sent to the bottom of the container and the water is moving enough to look like the water is boiling. Compost tea requires an “extraction” process, we must ensure that we are washing the microbes off the organic matter of the compost and have them “free floating” in the solution so that they are available to be activated and multiply in during the brewing process.

By: Doug Weatherbee

Doug Weatherbee — Thu, 05 Mar 2009 22:00:39 +0000

Neelam – you should go to Dr. Elaine Ingham’s site http://www.soilfoodweb.com/03_about_us/approach.html and read the Soil Foodweb approach. It begins to describe the microbial ecology of compost and soil. By working with microbes and adjusting the compost pile C:N ratio you can produce “designer” composts (bacterial dominance VS fungl dominance) for various soil and plant combinations. A key to making any compost is to keep it aerobic (Oxygen rich). Anaerobic (low Oxygen) microbes produce alcohols, phenols and turpenes (all bad for plants), burn off nutrients (like Nitrogen as Ammonia NH3) as smelly gases, and, if you put this anaerobic “compost” on your soil, introduce “bad” microbes to compete with your soil’s good microbes. Knowing the microbial makeup of your compost is key to understanding whether your compost is good or bad for the soil and plants you want to grow. For example, the discussion above about white matter in a compile may be not be good. It depends on the soil and plant combination you want to achieve. Often, white matter in a pile is Actinobacteria. Actinobacteria used to be classified as Fungi but have recently (through DNA testing) been classified as Bacteria. Actinobacteria dominated compost is great if you have a Fungi dominated soil (near an established temperate forest say) and you want to grow Brassicaceae (broccoli, cabbage, radish or cauliflower) in that soil. The Actinobacteria (white matter and fuzz) in the compost will inoculate your Fungi dominated soil moving it towards a Actiobacteria dominated soil that the Brassicaceae loves. However, if you want to grow fruit trees, Actiobacteria in your compost should be strictly avoided. Fruit trees love Fungo dominated soil particularly with endo & ecto mychorrizal fungi (depending on the trees as to whether endo or ecto). Anyhow, take a look at Dr. Ingham’s approach above and it will get you on your way.

By: Neelam Nazir

Neelam Nazir — Thu, 05 Mar 2009 09:58:37 +0000

hello sir
i would like to know about microorganisms of compost. can you help me??? sir i isolated few but to know about more…

waiting for your reply

Neelam Nazir

By: natarlee hickson

natarlee hickson — Sun, 23 Nov 2008 12:13:42 +0000

If you want PROPER compost you have to have the correct c & n ratio. the correct c/n ratio is 1 part very very fine woodchips/sawdust, 1 part green matter such as lawn clipings (excellent heat source) and 3 parts manure such as horse, cow, although you can use other manure such as sheep you will get the best compost if you use horse or cow poo.
You definately need to measure these items accurately either with a bucket or a wheelbarrow. start off your heap on soil and put each layer as described above, add a light sprinkle with the hose as you finish each layer DONT put too much water on it.after you’ve done the 1st layer put an agi pipe (1 that has slits in the side for air) in the middle of the heap, continue to build all your layers around that pipe, this serves to aerate the heap.

The higher you build the heap the better the compost will heat up and break down.

The white matter you will see after a couple of weeks in the heap IS GOOD MICROBIAL MATTER, so dont be alarmed if you dont have this happening your compost heap is not breaking down, a good compost heap which has been built (measured) to the above requirements will break down in around 8 to 9 weeks if it is turned each week, and not allowed to get to wet. You should also see lots of worms within the 2nd week, this means also that the compost is breaking down. When there is no sign of any solid content such as poo or fine wood chips/sawdust your compost is ready. You must not be able to see or distinguish any part of the original materials you put in your heap. Good Composting and BE PATIENT

By: Rebecca

Rebecca — Tue, 07 Oct 2008 12:34:45 +0000

This compost batch is wet (if anything, it could be too wet but hopefully not). I’ve turned it frequently but it does compact a little between turnings. I’m more inclined to think it’s a function of overheating…