Sustainable Garden

The Art and Science of Composting: Debunking a Few Misconceptions

Written by Manu

Above: Toby the compost tumbler in Lyttleton Gardens

Above: Toby the compost tumbler in Lyttleton Gardens

Let's face it, composting is a delicate subject. For seasoned composters, composting is a source of joy, satisfaction, but also pride, rigidity and strong belief that you've got it, you know how to compost, you hold 'the key recipe'. For people who are new to composting, it's a source of excitement as well as anxiety, as you constantly look for advice from 'experts' on how to get it 'right', not to mention the successes, failures, disappointments and a myriad other emotions. Ah the roller coaster ride of emotions that is composting!

Now that I am training in soil microbiology with Dr. Elaine Ingham and Dr Carole Anne Rollins, the two incredible powerhouses behind the Soil Foodweb Institute, I feel that I can now share info about what is actually happening biologically in a compost heap. This will help debunk a few misconceptions I have seen and heard.

I will have to break it to you though: there is no set 'perfect recipe.' Are you shattered... or relieved? People who are really good at composting seem to be the ones who know this, and go with the flow with no set recipe but a lot of knowledge on how to observe, adjust, smell, and even taste when things are right.

What goes on in your compost is heavily dependent on outside temperatures, moisture levels, ingredients, native microorganisms and a host of other external and internal factors. There are, however, a couple of things that apply pretty much universally. 

Firstly, whether you are hot composting, tumbling, cold composting or whatever else (except for bokashi), your compost needs OXYGEN to travel through it regularly. You need to aerate your compost regularly, whether it's in a pile or a bin. There are really cool, inexpensive screw-like contraptions you can use for bins these days. The good microbes you want to have in your compost and to apply to your soil are AEROBIC, which means they need oxygen to survive.

Secondly, you need a DIVERSITY of fresh, nitrogen-rich green materials (garden clippings or food scraps, composted manures, coffee grinds, bones) and dry, carbon-rich materials (like straw, dried leaves, wood chips and wood shavings). Remember to keep everything moist. Squeeze it in your hand, it should let out a maximum of one drop of water and feel moist. 

Thirdly, I find ratios a little hard to understand. I prefer Elaine Ingham's bucket method. Lets keep it simple. A good ballpark reference is at least three buckets of dry carbon-rich materials need to be added for every one bucket of nitrogen-rich materials. This applies to hot and cold composting! Many people keep adding food scraps to their bin thinking they will magically turn into compost. Although compost is indeed magical, it needs all players to be present. Otherwise the end product is rotten, putrified organic matter.

The nitrogen-rich materials are what generates bacterial activity which makes the pile heat up. If you have too many nitrogen-rich materials, your heap will heat up too fast too quickly and kill everything. Strong smells of ammonia, vinegar, vomit, poo in your bin or heap indicate that anaerobic microbes have taken over and are producing organic acids that are toxic to plants.

This is by far the most common mistake I have seen in home as well as large scale composts: too many nitrogen-rich materials, not enough carbon rich materials. Aerate it, add loads of dry, carbon rich materials to kickstart the process again in the right direction. Do not add lime as lime is (chemically speaking) a salt, and kills many beneficial organisms.

Hot or cold?

There is a little bit of confusion as to what constitutes 'hot' and 'cold' composting. In reality, all composts heat up to a degree. This heat has nothing to do with heat from the sun or outside temperatures. It is generated by microbial activity. In fact, I personally never put any of my composts in the sun as UV rays from the sun tend to kill beneficial microbes on the surface of your compost, or heat from the sun will 'cook' them in your bin.  

'Hot' composting involves buiding a big heap or bin all at once and letting it heat up in the centre. This heat (which can reach 70 degrees celsius or higher) has nothing to do with heat from the sun or outside temperatures. It is generated by microbial activity. Aerating the heap by turning it as soon as it hits the 65 degree mark, is essential because we do not want it to get too hot (no hotter than 65 degrees celsius), as this will annihilate all the microorganisms you need in your heap. I really suggest getting yourself a compost thermometer to take the guesswork out of the equation. Hot compost heaps tend to be more prone to drying out to water well when you build the heap and check the moisture each time you turn it. Remember a hot compost heap is all made at once i.e. no adding as you go. HOWEVER, if your standard compost bin is heating up, you are indeed hot composting, and it's time to aerate it. 

Cold composting involves adding as you go, which means it should not heat up anywhere near as much as a hot compost. Remember, for every one bucket of food scraps, you need to add three buckets of dry stuff. One cautionary note: anything that was cut when it was green is nitrogen-rich, even if you then let it dry. For example, dried up grass clippings are still a nitrogen rich material. Remember to check the moisture by squeezing it in your hand. Cold composting takes more time, but the end product has a wider diversity of beneficial microorganisms.

What about compost tumblers?

Technically, if you have a large enough tumbler, you can make hot compost (all at once) or cold compost (add as you go). I personally like to cold compost with my tumbler because it makes the cold composting process much faster through more frequent turning and, as I mentioned, the end product is incredibly rich and diverse in beneficial microorganisms.

I hope this helps debunk a few misconceptions and myths on composting and encourages you to delve into its magic!

Yarrow Gardens: Building a Food Forest From Scratch

Yarrow Gardens: Manu's back yard in the Lower Blue Mountains. In this shot, you can see Tuscan kale, yarrow, mugwort, rosemary, chamomile, dandelion, statice, broccoli, nigella, french sorrel, valerian, loquat tree, dwarf avocado, carrot and sweet potato.

Yarrow Gardens: Manu's back yard in the Lower Blue Mountains. In this shot, you can see Tuscan kale, yarrow, mugwort, rosemary, chamomile, dandelion, statice, broccoli, nigella, french sorrel, valerian, loquat tree, dwarf avocado, carrot and sweet potato.

In this post, I wanted to speak a little bit about my process setting up Yarrow Gardens: my home food forest in Lapstone, which sits on a standard, quarter acre block. I'm hoping this post will help those of you in suburban and peri-urban environments get started growing regeneratively in your back yards.

I live in the lower Blue Mountains, which has a warm temperate/subtropical climate, very different to Lyttleton Gardens, which sits between warm temperate and cool temperate.

When we first moved into our standard quarter-acre block, the sloped back yard was composed of three tiers of impacted, eroded, sandy, shallow soil covered in couch grass. Couch grass seemed to be the only plant resilient enough to grow in this depleted, eroded soil. A beautiful, twenty meter Eucalyptus tree stands tall in the middle of the yard, and friends and family assured me I would never be able to grow anything successfully because of it. I didn't know much about growing things at the time and my dreams of a veggie patch and fruit trees seemed close to impossible.

It was then that I embarked on my Permaculture studies, learning about ecology, microbiology, climatology, soil restoration, regenerative farming, holistic management and regenerative design. I slowly gained enough of an understanding of natural systems to be able to make conscious decisions about where to plant, what to plant, when to plant it, how to regenerate my soil and care for my little patch of topsoil.

My perspective had changed. I no longer saw plants as 'good or bad,' as I could finally understand the function of each plant within an ecological system. 'Weeds' were no longer evil, annoying plants to be pulled out, but rather resilient pioneers in charge of quickly protecting and attempting to restore bare soil after a disturbance. In a natural forest ecosystem, there is no bare soil, and that is largely thanks to their hard work.

The great big majestic gum tree was no longer a nuisance, but rather a canopy tree to be incorporated as such into my design. Being a medicinal plant lover, being able to pick medicinal plants straight from the garden to chuck into my kettle was one of my goals, along with having a good continuous supply of fresh fruits, berries and vegetables.

My partner Steve and I rented a rotary hoe and used its shallowest setting to uproot the couch grass. I got hold of about ten cubic meters of good aged mushroom compost (always check the pH as it can be way too alkaline) which I generously covered the soil with (about 15cm), followed by a good layer of locally sourced wood chip. This allowed me to begin planting and kick-started the process of restoring the soil by adding some organic matter.

Stage one

Stage one

Six months later

Six months later

Twelve months later

Twelve months later

The tree you can see in the top photograph is mugwort, a medicinal bush that I shape into a tree. It was a tiny seedling when I first put it in and grew very vigorously. I also bought some dwarfed or small trees to form an understory layer such as loquat, avocado, banana and pawpaw. For shrubs, I bought seedlings of fast growing plants like golden fruit of the Andes, wormwood, native ginger, Mediterranean herbs, perennial basil, midjim berries, acacias,  native mint, lemon verbena, comfrey, yarrow, and nettle. I broadcast seeds of nigella, roman chamomile, cornflowers, brahmi, silverbeet, echinacea, parsley, valerian, parsnip, carrot, daikon, chives, wild rocket, red sorrel, radish, warrigal greens and planted bulbs of potato onion, perennial leeks, Egyptian walking onion and garlic.

I installed drip irrigation last spring to make sure the soil was always kept moist enough for fungi, bacteria and earthworms throughout dry summers. Worm castings, seaweed solution, homemade compost and wood chips we my sole inputs for about a year. I also started inoculating my seeds with arbuscular mycorrhizal fungi (powder mixed with a little water) just before broadcasting and inoculated all my legume seeds with the appropriate bacterial inoculant (see my previous post on Nitrogen fixation).

We finally incorporated chickens into our system in the middle tier, where they are rotated to a different area every 8 months. They are fed grains and medicine from our garden as well as some bought organic feed. Their poo feeds and accelerates my compost, their eggs are a nutrient powerhouse for us. The system is thriving with minimal external inputs. We have nuts, fruits, berries, green veggies, eggs, potatoes, sweet potatoes and much, much more, providing us with a diverse, balanced diet. I occasionally foliar spray my plants with fish emulsion (fermented fish guts) and whole cows milk to keep them strong and healthy, but barely need to add anything to my food forest soil.

I feel good knowing that all of my perennial edibles and medicinals are storing carbon in the soil for the long term, while annuals growing among them are harvested regularly. Peanuts, potatoes, sweet potatoes, herbs and veggies now pop up on their own. If anything were to happen, we would have the ingredients to a balanced diet and fresh rainwater at our doorstep. An important element in hindsight was building paths throughout our food forest and maintaining them, for easy access and harvesting. I would say the process of building a balanced, productive system takes more or less 4 years, but as you can see in the pictures above, you can do a great deal in just 12 months with careful observation.

I want everybody to experience the joy of building their own little thriving ecosystem, providing refuge for wildlife, insects and microbes, whilst harvesting a bounty of produce. I hope this little blog post will provide you with some inspiration and tools to carefully observe your site and work with its specific conditions to design a healthy little food forest of your own.

Nature's Ploughs

Linocut Print of Earthworms by Manu

Linocut Print of Earthworms by Manu

This is what Charles Darwin called them: nature's ploughs. Earthworms and composting worms are my all time superheroes. My research on these gorgeous wiggly beings has been quite extensive in the last month, and I have learned so much.

Worms have hearts. Up to five sets of them. Their blood contains hemoglobin like ours. Their skin is very sensitive to light, which is why they like to live under sun shades made of decaying leaves and organic matter. Their 'teeth' are sand and rock particles inside their super powerful, muscly gizzards, which grind up organic matter.

What do they eat? Bacteria, fungi, nematodes, protozoa and organic matter: where there are earthworms, there are all of the above. Everything you need in a thriving soil food web. This alone makes it worth jumping up and down when you see them in your soil, but wait, there's more.

Soil passed through an earthworm has double the amount of organic matter it had before it went in. An acre of good soil contains two to three million of them, which can move about 18 tons of soil per year, over and over again. Doubling, tripling, quadrupling the amount of rich organic matter in your soil.

Worms also have special enzymes inside their gizzards which unlock chemical bonds chaining up nutrients. In other words, once these nutrients have traveled through a worm, they are finally in a form that plants have access to and eat. 

There are something like 7000 species of earthworms. Composting worms, such as the red Wriggler Eisenia fetida, prefer to live near the surface of soil, under leaf litter or mulch (or in your worm farm) in cool, moist, dark, oxygen-rich environments with a good amount of accessible food.

Deep-burrowing earthworms like Lumbricus terrestris are the ones that create horizontal or vertical tunnels going deeper underground, leaving space for oxygen, water and plant roots to easily penetrate the soil.

Their sensitive skin means they move out when synthetic fertilisers and glyphosate herbicides are used, subsequently leaving a gaping hole in the soil food web. No more worms, no more good microbes, a bit like the Brown Barbaloots moving out in Dr Seuss' The Lorax.

We need to look after these burrowing, shredding, wiggly, five-hearted beings with all our might.

Life webs

A rain-soaked spider web in Lyttleton Gardens.

A rain-soaked spider web in Lyttleton Gardens.

After you've been looking after a productive garden for some time, a wonderful thing happens: you get to the point where you are confident enough to sift through the myriad of information (and misinformation) out there, and realise that you have understood living systems enough to trust yourself.

My personal "aha" moment happened after reading a book by Jeff Lowenfels entitled Teaming With Microbes: The Organic Gardener's Guide to the Soil Food Web. I was intrigued by the term soil food web. I'd heard of food pyramids and graphs, but was drawn to the idea of a food web. It makes so much more sense. After all, all living things are inter-connected and inter-dependent. We've lost sight of that a little bit, often choosing a more symptomatic approach to many issues.

I looked into the person who initially came up with this term. It was Elaine Ingham, Doctor of Soil Microbiology at Colorado State University. The Soil Foodweb Institute, founded by her in 1996, has been helping conventional farmers 'rehabilitate' their soils, and switch to growing organically and regeneratively. She worked extensively in this field in Australia, and started the Australian branch, Soil Foodweb Institute (Australia).  The Soil Foodweb International website contains a huge amount of free information and research in the field, which I really recommend to anyone interested in the science of growing things.

Without getting to scientific about it all, it's important to remember that soil is populated by squillions of living things, which directly or indirectly depend on plants and plant roots to obtain food. In turn, plant roots depend on them to eat. Bacteria and fungi make nutrients bio-available to plants by converting them to a form plants can eat. It's a swap system!

Synthetic nutrients are plant fast food, as they are already in a bio-available form. So, what happens when we feed our plants synthetic fertilisers? Well, essential living things like bacteria and fungi move out. They are no longer needed by the plants and don't like the salts in fertilisers. In turn, there is no food for earthworms, and their predators, and their predators' predators, and so a mass exodus happens. All life in the soil disappears. The web of life is broken and plants become junkies, fast food junkies. The soil becomes "dirt" as Elaine Ingham puts it. Lifeless, erosion-prone dust.

This is why growing regeneratively is so important. You are a custodian of all the living things in your soil. Feeding your soil homemade compost, worm castings and aerated compost teas makes sure there is food for everyone in the web, with very little need for external inputs. Try not to disturb it too much, as the earthworm will aerate it for you. Pitchforks are relatively worm-friendly if used appropriately.

Let's get something straight though, the process of building living, healthy soil takes time and patience. Keep piling on that organic matter and remember you are feeding many living things, which in time will multiply. After quite some time, all that work pays off and you will have to do less and less, as the web will be complete and self-regulating. What a wonderful, joyful prospect that is for a budding grower of things.

Soil food web diagrams from the Soil Foodweb International website.

Soil food web diagrams from the Soil Foodweb International website.



Perennial Edibles: Low Maintenance Food Growing

Let's face it, growing annual vegetables is quite a bit of work. It requires dedication, persistence, and is sometimes risky business! How many times have you carefully and lovingly looked after your beloved broccoli, only to come out to the garden one morning and find it had been devoured by rats, birds or possums?

This is why it's a good idea not to put your eggs in one basket by growing a variety of edibles and including perennial edibles into your productive garden design. As opposed to an annual plant, which has a life cycle of six months to a year, perennial plants can last 5 to 15 years or more! There are hundreds of varieties of perennial edibles, many of which are described in a wonderful book written by Eric Toensmeier entitled Perennial Vegetables, which I really recommend.

As chance would have it, you already are growing some perennial edibles in your garden like rosemary, lavender or thyme. You may have inherited them from your landlord or the previous owner of your home and they happily provide you with a constant supply of herbs (and provide the bees with wonderful nectary flowers) year after year. What giving plants they are!

As it turns out, perennial vegetables work much in the same way. The wonderful thing about them is that they are often very hardy and low maintenance. Many thrive in part shade, so are a wonderful option in a shady garden. You plant them once and they will provide you with fresh food season after season.

Let's go through a couple of our favourites:

- Salad burnet is a wonderful perennial, peppery, leafy salad plant that will provide you with a constant supply of salad greens all year long for years to come. It is a great ground cover layer in a permaculture food forest and is very easy to grow. That possum we mentioned above can literally eat it right to the ground, and burnet will come right back and grow more vigorously than before!

- Lovage is a wonderful celery substitute as you only need one stalk of lovage in your stew to replace three stalks of celery!

- Perennial leeks are fantastic as they provide you with a constant supply of leeks (smaller than traditional ones, but much tastier) by constantly sending out new baby leeks that you can divide and re-sow.

- Gotu kola is a great bog plant (for boggy, shady areas in your garden) said to alleviate and prevent arthritis.

- Asparagus can live up to 20 years! Now is a good time to plant asparagus crowns. I would plant about four for one household. They will start producing a good amount of spears in their second year, die back every winter, and come back every spring!

- All members of the mint family are wonderful medicinal edible perennials, although you may want to plant them in a pot as they do tend to take over. One of these, which we have a lot of in our vegetable garden, is lemon balm. It is one of our Naturopath Sarah Mann's favourites. We have a Holistic Gut Health Weekend coming up in our workshop space and lemon balm is a herb that will feature for its ease of growing in the Blue Mountains and it’s incredible help restoring gut health.  It has the most beautiful, warm, citrusy and refreshing scent. A low mood or lethargy is transformed with it’s beautiful aroma, lifting and strengthening the spirits and sharpening the mind. Lemon balm is a powerful anti viral and anti microbial, sweeping the gut clear of unhealthy bacteria and bugs while nourishing and repairing the gut. It is warming, calming and enlivening, bringing the gut into a supple and supported responsiveness and providing a landscape for healthy gut flora.

Perennial herbs, vegetables, and fruit (most fruits and berries are also perennial of course) play an important role in a diverse, productive garden providing long lasting yields of food and medicine, nectar for beneficial insects and different edible 'layers' in a food forest ecosystem.

Our Beautiful Compost

In Lyttleton Gardens, we turn all scraps from the house and shop into beautiful, rich compost. Since we are lucky enough to get a large volume of scraps, we use the 'thermophilic' or 'hot composting' method.

This means we build our heap using relatively equal parts of nitrogen-rich food scraps and carbon-rich straw, and sprinkle in some lactobacillus (optional, more on this in a future post). We then let the heap warm up. It does this on its own as the bacterial activity within the heap generates heat. It can go up to 60 to 65 degrees Celsius! We then turn our heap every 2-3 days, and within 3-4 weeks, we get beautiful, sweet-smelling, rich organic compost.

You know you've got it right when it smells earthy. This smell is due to actinomycetes, bacterial decomposers that produce enzymes including volatile chemicals that give soil its clean, fresh, earthy aroma. Once the heap cools, the worms move in, with their nutrient-rich castings. They aerate the compost by going about their usual business. 

Applying copious amounts of our compost at the foot of our rutherglen bug-affected plants and mulching heavily has helped hugely. Populations have balanced themselves out, and plants look strong and happy again. Hurray!