On Farm Composting

How to make simple, low labour & high-quality compost.

What is compost?

Composting essentially involves the use of certain practices and methods to manage decomposition and effectively turn organic residue into a valuable product that is used to benefit plant growth.

A word on decomposition

Decomposition is a naturally occurring process that is important for the health of terrestrial ecosystems.

There are various populations of micro organisms that consume and incorporate the dead organic materials that end up on the surface of the soil.

In the process:

The materials are broken down and inherent nutrients are liberated, making them available to be utilized by biology once again.

Remaining organic matter is reduced to minute humus fractions that are all important for soil structure, moisture retention and nutrient holding capacity.

Numerous biochemical compounds are produced by the various microbiological populations that stimulate surrounding biology, induce pest and disease resistance and promote plant growth

In natural environments, this is a gradual and ongoing process that is very much dependent on availability of materials and prevailing conditions.

Decomposition

Not All Compost Is Created Equal

Characteristics to look for when assessing the quality of compost include:

Smell: a pleasant earthy aroma
Colour: a dark, rich chocolate colour
Mature: well broken down without any recognisable parent material
Consistent: uniform in texture
Structure: light and crumbly
Bolus: can be moulded like soft putty

Feels like putty..

Biological Assessment

Compost samples can also be looked at under the microscope to get a general picture of the biology it contains or sent to a laboratory for DNA or enzyme analysis to get a more detailed breakdown of the microbiology present.

Nematodes & Protozoa

Australian Standard

Certified compost products must be within certain thresholds when it comes to things like chemical contaminants, plant propagules, pathogens, the occurrence of glass, metals, plastics and stones etc.. In order for compost to qualify and be branded for sale as a certified product it must comply with Australian Standard 4454. This is quality control system that outlines the criteria that must be met in order for compost to qualify as a certified product (see example below). It guarantees consumers the compost they are buying has met these standards.

Can you tell the difference?

Fungi up close & personal

Bolus

Setting the Scene

The site, equipment and materials you need to get compost production underway

Compost Building Site

Things to consider when identifying your compost making site:

Space: is there enough space for stockpiling of materials and equipment.
Access: can we get to and move around everything with ease.
Proximity: is it close enough to feedstocks, equipment, paddocks or where you want to take it.
Water: Is there a readily available source of water on hand
Drainage: is the site free from waterlogging
Protection: is it protected from the sun, wind and rain.
Weeds and pests: are there problematic weeds or pests in the area that could impact operations
Neighbours: feedstock materials can be smelly and the movement of machinery is noisy so must be suitably distanced from neighbours.
Surrounding Environment: nutrient rich runoff can negatively affect wetland systems and traffic may impact on sensitive wildlife
Regulations: each state has different regulations that need to be adhered to in WA land managers must follow the DWER Regulation Guidelines

Composting materials are piled close to the windrow sites, then moved to more manageable banks that are suitable for the mixing machine.

Access to water is key

Equipment

Equipment needed may include:

Pitchfork/shovel...
Machinery - tractor, turner, mulcher...
Garden hose/firefighting unit...
Mixing buckets, backpack sprayer, watering can...
Tarp, weedmat etc...
Thermometer
Infrastructure - pallets, wire mesh etc...
PPE - gloves, mask etc...

Feedstocks

Feedstocks are the raw ingredients needed to make your compost. Some things you want to consider when sourcing feedstock materials are:

C:N ratios

Quality

Cost

Availability & Accessibility

Particulate size

Contamination - biological, physical, chemical

Diversity

Ease of Handling

A good hay fork makes things easier

Compost thermometer

Different feedstocks

Making Compost

Podcast Snippet: Jo & Kate talk to Agroecologist Mark Tupman on all things compost - what to put in it, how to make it, and how to use it on your farm.

Tune In to the Full Podcast

To make compost well, we need to provide the microorganisms involved with a good balance of the food, air and water they require, and suitable living conditions.

To break it down further, the composting process is all about how we manage the following areas:

Feedstocks
Additives
Mixing
Pile Construction
Moisture Level
Aeration
Temperature control
Protection

Microbial Foods

Carbon based materials provide the energy that fuels microbial activity. Sources include woodchips, prunings, clippings, crop residue, shredded newspaper, bran etc…

Nitrogen rich materials are integral for building the protein required by microbial biomass. Sources include manure, animal matter, blood and bone, legumes etc…

Fresh plant and animal materials, while not essential, bring a range of active microbes, vitamins, hormones and enzymes that contribute to the overall diversity and health of the biology in the compost heap. Sources include greens, fresh pruning's, weeds, grass clippings, crop waste, seaweed etc…

Additives

There are additives can be included along with bulk foodstocks, when making compost, that have qualities known to enhance favourable characteristics of compost .

These include things like:

Rock Minerals

Calcium Sources

Trace Elements

Ash

Diatomaceous Earth

Biochar

Bonemeal

Zeolite

Inoculants

Clay (powder)

Seaweed (liquid or powder)

Zeolite

Inoculants

Seaweed (liquid or powder)

Generally speaking, 50-60% carbon-based materials, 10-20% nitrogen rich materials and 20-30% green plant materials by volume and 5-10% additives by weight are reliable ratios to work with.

A good visual analogy for quantities of different types of ingredients to use in compost is a pasta dish. On your plate you generally have a decent amount of spaghetti (carbon based ingredients), with some pasta sauce topping (nitrogen rich ingredients), a side salad (fresh plant materials) and a sprinkling of salt and pepper (additives).

Building the Heap

When assembling a compost heap it is important that the different types of materials are either layered in repeated sequences and/or mixed well beforehand so that microbes have ready and even access all the feedstocks. This makes for a homogenous product in a shorter time frame.

Adequate material bulk is necessary if you want to create thermophilic conditions. However, if piles are too high, it is prone to getting too hot and lower layers may compact. With such composting, an appropriate height would be in the vicinity of 1.2-1.5m. Bulk volume is achieved with succinct stacking of rows or piles or the use of a bay or cage to contain the materials.

Protection

Exposure to extreme weather can be problematic so it may best to set up your compost in a somewhat sheltered spot. Providing a semi permeable (to allow for gas exchange) protective covering reduces evaporative water loss and generally helps to regulate conditions within the heap, making for more uniform decomposition.

Water

Hydration is a must for microbial activity and movement, otherwise they go dormant, or die.

When making compost, dry ingredients should be wetted, and throughout the life of a heap, moisture levels must be monitored and maintained to prevent it from drying out. On the flip side, if it gets too wet, air supply is compromised and soluble nutrients are prone to leaching. Ideally compost materials should be moist but shouldn’t any release water without applied pressure. Some micro-organisms and worms, don’t fare so well in hard/saline/chlorinated water. If you’re going to get serious about making compost it might be worth checking your water quality.

Air

Oxygen is critical for the respiring organisms that participate in the highly active decomposition that takes place when there is a stack of fresh food and adequate air and moisture on hand. However, if oxygen is not replenished as fast as it is used, the inherent oxygen quota can be exhausted, creating less favourable, anaerobic conditions. This is most likely to occur with larger volumes of, or compacted, material as movement of air to the inside of the heap is somewhat restricted. If this is the case, maintaining adequate oxygen levels requires active management, especially in the early stages when microbial activity is high. Compost can be systematically turned during this phase to maintain oxygen levels. Another approach is to set up compost systems with physical and/or mechanical components that insure sufficient aeration throughout the heap without turning.

Temperature

When the microbes really get going they burn lots of energy which generates heat. The greater the volume or density of the materials, the longer it takes for heat to diffuse from of a compost heap. When a decently sized compost heap is assembled with suitable feedstocks, it doesn’t take long for things to hot up to what is referred to as thermophilic conditions (>50C). Higher temperatures may be handy, because if sufficient heat is generated, undesirable pathogens and weed seeds are destroyed. All material needs to have been maintained above 55C for a minimum of three days to achieve this sterilisation standard. However, at temperatures above 65C, many beneficial microbes are destroyed.

The same conditions that predispose compost heaps to restricted gas exchange also lead to higher temperatures, and in this way, the temperature provides some indication of oxygen status. Most commonly, aerobic thermophilic compost systems are turned to release heat and replenish oxygen.

Alternative composting methods such as static aerated, contained environment fermentation and continuous feeding systems are less conducive to creating thermophilic conditions.

As the supply of high-energy foods gets used up, activity naturally slows down. Not as much heat is generated making for cooler conditions (<40C) that eventually stabilise at ambient temperatures. Over this maturation phase, a broad community of bacteria, fungi, protozoa and nematodes slowly decompose more persistent organic materials. Strong fungal colonisation is possible at this stage and disturbance should be minimised in order to avoid damaging their fragile hyphae. When the temperature is goes below 30C, composting worms can be introduced to the heap to further the decomposition process.

Over time, any remaining organic matter is broken down into minute humus fractions that are increasingly resistant to further decomposition.

Assembling a heap

Mineral additives

Layering feedstocks in a windrow

Inoculating the windrow

Mixology!

Gettin' hot in there!

The Phases of Common Composting

In each phase of composting, specific substrate components are degraded and a varying product quality is achieved.

During the first phase, mesophilic organisms prevail (e. g. acid- forming bacteria and sugar-utilising fungi).

With a transition to the thermophilic phase, a species change takes place to a less broad range of thermophilic bacteria and actino- bacteria and only a couple of thermophilic fungi.

At 65 °C, fungi have usually completely withdrawn.

At higher temperatures, the actinobacteria also withdraw. At temperatures in the self-limitation range (at approximately 75 °C), the richness in species is very limited and Bacillus spp. prevail.

With the decreasing temperatures during the cooling phase, micro-organisms' surviving through spores and formation of conidia, or which were introduced from outside, re-colonize the substrate.

During the second mesophilic phase, fungi in particular prevail; as they are adapted to the substrate components which are less degradable and to the substrate humidity that tends to be lower.

(summarized from various literature in Korner 2009)

Regardless of the chosen method, in many ways the art of making good compost lies in our ability to manage these different stages of decomposition so that the various microbe groups can do their thing and turnover a quality product.

Thermal aerobic turning

Different types of composting systems:

Aerobic Thermal

This composting system is assembled and managed in such a way as to ensure materials are subjected to defined temperatures, for sufficient periods of time, to kill weed seed and pathogens (without getting so hot that beneficial biology is destroyed) whilst maintaining adequate oxygen levels for robust microbial activity. It involves routine monitoring and systematically turning the heap in accordance with temperature and duration thresholds to maintain suitable conditions and rotate materials through the hotter centre of the heap.

A standard recommendation is to turn within three days at temperatures between 55-60C, turn within 48 hours at temperatures between 60-65C and turn immediately if temperatures go above 65C. There is also a requirement to replenish water that is lost, as vapour, in the process. Large volumes of material can be placed in windrows and handled with suitable machinery, making for the efficient turnover of a product that meets composting standards.

Static Aerated

Static Aerated compost systems usually involve a structural component that enables good airflow to replenish the oxygen used by respiring microbes during the more active phases of decomposition.

Another feature of this type of composting system is that heat generated by microbial activity, dissipates at a faster rate, preventing the temperature from exceeding certain thresholds. Because oxygenation and temperature are self-regulated, these systems don’t require any turning. The inherent conditions favour beneficial microbial populations and the lack of disturbance makes for better colonisation with fungal hyphae.

Usually, some sort of air channelling set ups such as perforated pipes are used to deliver air through the materials which are often assembled on mesh structures or pallets so that air can get in from the bottom. Mechanical elements, such as fans or exhausts, may also be used to improve airflow. In some systems, the structural components are removed or once they’ve served their purpose and in others they remain for the duration of the composting process. On a smaller scale, larger sized organic materials such as woodchips, straw and branches can included and/or used as structural components to enable better airflow. Static aerated compost systems generally turn out high quality compost but construction constraints limit the volume of compost that can be processed with each batch.

Contained Environment Fermentation

There are a large group of bacteria and yeasts, collectively termed facultative anaerobes, that can switch to anaerobic respiration or fermentation, in order to acquire energy from organic materials, when oxygen is limited. Less carbon is lost from organic matter under these metabolic pathways than with respiration, and it favours the the formation of stable humus.

Contrary to common compost practice, airflow in fermentation systems is purposely restricted, and moisture is maintained at higher levels. Materials are normally wetted, inoculated with a starter culture, combined, and then contained or covered to restrict the supply of oxygen.

Larger volumes of material are best mixed and turned a couple of times to release heat and get the moisture levels right before covering. In the fermentation process, the pH can drop to around 3.5-4.5. No further turning is required once assembled and covered and there is little moisture loss as it is a contained environment.

Vermiculture

The principle behind continuous feed vermiculture systems is that you only add smaller amounts of feedstock material at a time to keep them from getting too hot for worms. Alternatively, larger amounts of material can be partially composted first to get past the thermophillic phase before worms are added.

Materials can be gradually fed to worm farms or batches can be laid out in low rows on permeable fabric. The depth of fresh material in either case is no higher than half a meter high to ensure the temperature doesn’t go much above 30 degrees C. Adequate moisture levels must also be maintained for worm habitation.

Some sort of system needs to be in place to enable harvesting of the worm casts without the worms. Mesh bottoms that castings fall through can be used in top fed systems. In horizontal systems, the castings may be harvested once the worms have finished and moved on to fresher batches of materials or more favourable conditions. By their nature, vermiculture systems are typically designed to take more regular, but lower, volumes of feedstock.

Compost Method	Pros	Cons
Aerobic Thermal	Heat kills pathogens and weed seed, takes less time, can process large amounts of material.	High management/maintenance, loses a higher amount of carbon, nitrogen and water
Static Aerated	Easy, low maintenance	Doesn’t adequately heat all material, low volume, takes longer
Fermentation	Low maintenance, uses less water	Doesn’t adequately heat all material
Vermiculture	Can continuously feed, high humus	Doesn’t heat sterilize material, slow turnover

Turning a thermal aerobic compost windrow

Turning a thermal aerobic compost windrow

Building a Johnson Su Bioreactor

Building a Johnson Su Bioreactor

Filling a Johnson Su

Finished Fermented Compost

Finished Fermented Compost

Guidelines to Making Different Composting Systems

Biocomplete Compost (Agpath)

Controlled Microbial Composting (Luebke)

Johnson Su Bioreactor (Dr David Johnson & Hui-Chun Su Johnson)

The Worlds Best Compost (Rod Turner)

SPICE Compost (Soil Land Food)

Vermicomposting

Getting the Most Value Out of Compost

Target applications to benefit plant growth for the subsequent benefits that come from having heathy plants in the system

Using compost, and slurries/extracts of, at planting to coat seeds, for in furrow liquid applications or as a seedling dip is very economical as only small amounts are required to aid the establishment of a healthy plant microbe biome from the start.

Rhizosheaths on seedlings from seeds treated with compost extract

Rhizosheaths on seedlings from seeds treated with compost extract

We can stimulate microbial activity and boost populations with the addition of biostimulants and foods prior to application.

Compost can be mixed and applied with water to improve distribution, coverage and infiltration.

The timing and placement and method of application can be targeted to maximise efficiency and/or tailored to desired outcomes

Some fertilisers can be mixed and applied with compost to improve availability, uptake and stability

It is best to carry out compost applications in favourable conditions and avoid extreme weather events to prevent loss of or compromise qualities of the applied product.

Compost is generally used to improve:

biological activity
plant nutrition
pest and disease resistance
soil structure
nutrient and water holding capacity

Large volumes of compost are required to fertilize or condition soil, however, smaller volumes can be utilized strategically as part of an integrated program to enhance soil fertility and function.

Coating seeds with a compost slurry

Compost Application Rates

Soil Amendment	Seasonal Top Dressing	Banded/In-Furrow	Slurries / Extracts / Teas
5-50 tonnes/10-100m3 per hectare	0.5-5 tonnes/1-10m3 per hectare	100 kg – 1 tonne/0.2-2m3 per hectare	1-10 kilos per hectare

Additional Resources

Farming with Compost (Soil Land Food)

Estimated Carbon to Nitrogen Ratios

The Art of Making Fine Compost (Productive Ecology)

In this episode of Talkin’ After Hours Jo & Kate chatted to molecular biologist, Dr David Johnson & his wife Hui-Chun Su Johnson about David’s research and development of an agricultural management method called BEAM (Biologically Enhanced Agricultural Management) and the now renowned composting system he devised with Hui-Chun called the Johnson-Su Compost Bioreactor.

Fermentation Compost Inoculant (Soil Land Food)

Making a Johnson Su Bioreactor

Compost Extract & Slurry Recipes (Productive Ecology)

In this Talkin’ After Hours webinar, presenters Dr. David C. Johnson, molecular biologist and senior research scientist at New Mexico State University (NMSU), & his wife Hui-Chun Su Johnson, discuss the simple & low cost ‘make on the farm’ tool & method they have developed, the Johnson Su Biorector Comporting System that can assist land managers to bring their soils back to life. Also discussed are the he results of Dr Johnson's research on the impact of using Johnson Su Composting system & BEAM as a low cost alternative to the use of synthetic fertilsers on crop/pasture productivity, its impact on soil aggregation, water infiltration & retention, and the soils capacity to sequester carbon.

This document is a downloadable summary of the online article & content hub ‘On Farm Composting’.

About this Article

Our Writers & Presenters

Mark Tupman

For over two decades Mark has been active in the fields of organic/biodynamic production, permaculture, sustainability, agro-ecology and holistic management and in between times managed an orchard, animals and food gardens on his own property.

Through his business, Productive Ecology, Mark provides consultation and education & training in the establishment of integrated living production systems. More recently Mark has been consulting on a range of soil health related projects and activities to the Lower Blackwood Landcare Group

David Hardwick

David Hardwick, is an agroecologist & partner in the rural change management company Soil Land Food.

David has over 20 years experience in rural landscapes, farming and food systems. He develops and delivers many of the extension projects for Soil Land Food across Australia.

David's work has covered landcare extension, agronomy, soils, agribusiness, biofertiliser R&D and manufacturing, organics, training, and consulting positions. David’s passion is agroecology and empowering farmers with knowledge and skills that make a difference!

This article was produced by 'Talkin' After Hours', the Lower Blackwood Landcare's Online Community & Information Hub

The article was written by Mark Tupman from Productive Ecology, and includes a compilation of information disseminated during a collaborative roadshow that took place across seven catchments in the south west of WA in June 2023 to encourage farmers and landholders to build their knowledge and skills to make and use compost.

The roadshow was coordinated by the Lower Blackwood LCDC in collaboration with six other catchment groups across the southwest, and is funded through Soil Wise. Soil Wise is funded by the National Landcare Program Smart Farms Small Grants – an Australian Government initiative. It is supported by Healthy Estuaries WA – a State Government program.