The Art and Science of Composting
Decomposition is a microbial process critical to life on this planet. Minerals are recycled, carbon is sequestered in the soil as humus and soils are constantly regenerated in a cyclical fashion. This natural decomposition involves the same processes found in composting. However, composting involves the fast-tracking of these natural processes through human intervention. Here, the efficiency of decomposition is maximised through a fusion of science and art. Composting has been an integral part of agriculture for centuries but the science has greatly expanded in the last ten decades. During that same period, extractive agriculture has seriously depleted the mineral and microbial base in our food producing soils, so the need for informed composting has never been greater. In this article I will highlight the multiple benefits of compost, discuss the most effective strategies to produce your own compost and I will also share some of the cutting-edge strategies to enrich your compost.
The Beauty of Compost
Water is rapidly becoming our most precious resource. Countries will wage war to secure supply (if that is not already happening). The use of compost is a premium water saving strategy. It contains around 25% humus and it also promotes the humus-building organisms in the soil (many of whom are desperately in need of some help). Humus can store more than its weight in water (Podolinski (1985) and Kay (1997)) and the building of organic matter levels on your farm, or even in your garden, can make a tremendous difference to your soil’s utilisation of irrigation water or a rainfall event. In fact, the difference is staggering! If you can build your soil humus levels by just 1% then your soil can store 170,000 litres per hectare that it could not previously store. That equates to 17 litres per square meter! Remember that this is water that the plant can access at will. There is no energy required to deliver that water and there is no evaporation factor involved (like dam storage). It really is the ultimate in water storage and efficient water delivery system. In addition, any carbon that we store in the soil, as humus, is not returned to the atmosphere (as part of the carbon cycle), where it is causing so many problems. Building 1% humus in the soil actually binds up 50 tonnes of CO2 per hectare that would otherwise be thickening the greenhouse blanket. Growers will soon be paid for this stored carbon and this will prove a remarkable win/win situation. In fact, there are so many benefits associated with humus building, it is a shining example of a bountiful universe that responds in kind – it is a thing of true beauty.
The Compost Bounty
Humus does not just store moisture more efficiently than any other technology; it is also the best tool to retain nutrients in your soil and to deliver those nutrients to the plant. Humus is the only soil colloid that is equipped with sites to store both negatively charged minerals (anions) and positively charged minerals (cations). This is particularly important in relation to the storage of highly leachable anions like nitrate nitrogen, sulfates and boron, because the humus colloid is the only storage mechanism in the soil for these minerals. Notoriously unstable minerals like phosphorus, which lock up in the soil at an astounding rate (an estimated 73% of your soluble phosphate fertiliser investment becomes insoluble) can be stabilised with the formation of a phosphate/ humus bond.
The delivery of minerals to the plant is largely a biological process and the higher your humus levels, the more active your soil biology and the more nutrient-dense your produce. Food can become a feast of forgotten flavours and these flavours are directly related to the medicinal value of the food.
Improved soil structure is a well-researched benefit of compost application. Soil aeration, porosity and crumb structure are all enhanced. Compost is food for soil life. Earthworms return to composted soils, as do the less visible creatures. I recently applied a healthy dose of compost to just one half of a large flowerbed at my home acreage. Six months later the difference is outstanding. Plant growth is more vibrant, the soil is more friable and there is double the number of earthworms in the treated half!
Microbes and Minerals from Compost
Compost also serves as a microbial inoculum to restore your workforce. A teaspoon of good compost can contain as many as 5 billion organisms and thousands of different species. These beneficial microbes restore biodiversity and the balance that comes with it. This balance can create a disease-suppressive soil. These beneficials neutralise pathogens through competition for nutrients and space, the consumption of competitors, the production of inhibitory compounds and induced disease resistance (via a plant immune boosting phenomenon called systemic acquired resistance). Compost has also been shown to promote the development of mycorrhizal fungi (AMF).
Minerals complexed with humus in compost will not leach like water-soluble fertilisers. African research has demonstrated that when minerals are included with compost they were much more efficient than the uncomposted fertiliser (up to ten times more efficient). Microbe exudates can also prompt the plant to uptake minerals. There is an additional benefit when combining compost with fertilisers. The stable, slow release minerals in compost can help to avoid the plant overloads that sponsor pest pressure (nitrate-packed, low brix plants are a good example).
Raw Materials – What To Embrace
The recipe for successful composting always involves one critical factor. The balance between carbon and nitrogen (the carbon to nitrogen ratio) determines the speed and efficiency of the composting process. The best form of nitrogen is animal manure as it also offers a rich microbial inoculum. Each form of animal manure offers a different range of organisms but it is generally considered that cow manure is the best. The rumen is something of a biological masterpiece in itself and the poo contains a comprehensive representation of this remarkable internal workforce. Rudolf Steiner, the founder of biodynamic agriculture, believed that a farm was not a farm without the presence of cattle. The most famous of the biodynamic preparations involves cow manure deposited in a cow’s horn and buried until it is composted (and infused with other energies).
The carbon component of the compost recipe can be sourced from whatever is closest to hand and least expensive. This may involve spoiled hay, orchard litter, feathers, stable straw, sawdust, municipal mulch or spoiled fruit and vegetables.
There are two other components that have proven particularly productive if they can be readily sourced. Soft rock adds calcium, phosphorus, silica and clay. The clay component greatly extends the life of the compost. Basalt crusher dust can contribute broad-spectrum minerals, if it is finely crushed, but more importantly it supplies paramagnetic stimulation to the compost.
What is Paramagnetism?
Professor Phil Callahan is a highly accomplished scientist and writer responsible for multiple published papers and books covering diverse subject matter. He was able to identify paramagnetism as the reason that volcanic soils always outperform non-volcanic soils. These soils can attract store and convert atmospheric energy (Extra Long Frequency (ELF) radio waves originally created from lightning) into tiny light particles called photons. Photons effectively deliver a light source to the roots and the creatures living around the roots (the rhizosphere). Paramagnetic stimulation can treble the activity of beneficial microbes (hence the enhanced performance of volcanic soils). There is a proven synergy between compost and paramagnetic crusher dust. During my original interview with Prof. Callahan in ‘Nutrition Rules!”, he cited a visit to the German laboratories of Professor Fritz Popp, a leader in the field of light energy research. He arrived from the US with a sample of basalt and asked that it be tested using the cutting-edge equipment available at the lab. To the amazement of Prof. Popp the sample had a reading of 4000, demonstrating that the rock was steadily releasing light particles. However, the next day Prof. Callahan returned to the lab with a sample that involved a combination of the same crushed rock combined with compost. The photon reading had increased 100 fold to 400,000! You can really get your compost cooking and increase the efficacy of the end product with the simple addition of crusher dust and it need not involve a great expense. You will need between 6% and 10% crusher dust in the mix for optimal results and this can be sourced locally, if the paramagnetic reading is high enough. The dust should have a minimum reading of 1600 CGS to justify its use. There is a trap for young players here. The PCSM meter can not differentiate between ferro-magnetism and paramagnetism and this means that if your local crusher dust features a particularly high iron content, then you have no way of knowing if the sample is actually paramagnetic. The solution here is to take a couple of buckets of the dust home and apply it to a section of your home garden. You will see an obvious response if it is truly paramagnetic but there will be very little response if the iron content was confusing the reading.
Raw Materials – What to Avoid
There are several raw ingredients that can reduce compost quality and/or contaminate the end product. Chemically treated wood products cannot be used, as the arsenic involved can be a serious pollutant. Meat, bones and fatty foods tend to attract pests (like rats) and they can also stink during their breakdown. Weeds should be avoided. The seeds can be killed with the heat of composting but it is not worth taking the risk. Similarly, it is not a good idea to try to compost diseased plants in case some of the disease organisms escape sterilisation during the heating phase. Cooch and nut grass should be avoided, as the rhizomes will often survive the composting process. Pet litter can harbour human parasites and disease (particularly used kitty litter) and large quantities of pine needles can have an inhibitory effect due to the extreme acidity of this material.
Composting Techniques – What works Best?
There are several popular composting strategies and each of them has merits. Your choice will depend upon your access to raw materials and the maturation speed you are seeking. The level of management involved is a key differentiation between approaches. The maturation time can vary from eight weeks to two years depending on how much time you choose to invest. Here is a brief overview of the most popular composting techniques:
Static Pile Composting
This technique, popularised by US compost guru, Malcolm Beck (The Secret Life of Compost), takes twice the time to produce (compared to windrowing) but there are several pronounced benefits. Here, the all-important aeration comes from air spaces in the mixture determined by particle size. This technique will not be an option for you if you only have access to cow manure as a standalone input because there will be no air spaces and undesirable anaerobic conditions will prevail. However, if you also had access to orchard prunings or Council green waste you would have the perfect material to layer the manure with, producing a well functioning static pile. These large, three-meter high piles are only disturbed three or four times during the 6 month composting process and this non-disruptive approach has several advantages. There are much lower energy, machinery and fuel costs involved and there is also less labour required. One wonders whether more actively managed piles actually result in a net carbon gain, when so much energy is involved in their production. Static pile composting can produce excellent compost with more humus, more nutritional value and higher counts of beneficial fungi. This quality improvement is related to reduced fungal disruption and a lower loss of CO2 (from turning). There is also less leaching of minerals (due to a lower water requirement).
There is still an option for you to use the static pile technique if you have a mountain of cow manure and no material available to produce air spaces. Static piles can be aerated by either blowing or sucking air through the stack. It has been found that alternating air movement can promote a similar temperature and moisture throughout the pile. A caged blower fan can be used to push air through a perforated, 4 inch, plastic drain pipe. The pile height should always be less than three meters to maintain uniform aeration.
Small-Scale Static Piles for the Home Gardener
The compost experts often sell the concept that there is no likelihood of producing a good compost unless some level of active management is involved. This is not the case. Non-energetic home gardeners can pile up their lawn clippings and fallen leaves and recycle these organics without the effort of regular turning. The key here is to avoid the addition of a nitrogen-based accelerant. The materials can sit undisturbed and decompose for up to two years and can still result in an acceptable compost. The piles should be covered by black plastic, sacking, or an old carpet and they may still need watering if they begin to dry out.
Actively Managed Compost
This technique involves commitment and considerable energy to achieve a high quality compost. For example, the pile may require turning every day, during the first ten to fourteen days. The pre-sourced green and brown materials are usually pre-shredded and added in layers to form long narrow windrows between 1 to 2 meters high and 2 to 3 meters wide. Large, compost-turning machines are typically used in windrow composting. CO2 is the gas released as the microbes breathe, so it is a good strategy to monitor this gas with a meter as an indication of microbial activity. These windrows are bacterial dominated because the fungi are repeatedly sliced and diced during the turning process. Moisture must also be monitored and there is much more applied water involved due to the reduced insulation in smaller piles. The compost is produced in just 10 to 12 weeks and this has become the favoured approach amongst commercial compost producers looking for rapid turnaround.
Vermi-Composting – Worms Do the Work
The worms involved in vermi-composting are not the same earthworms found on your farm. They are special, purpose-bred composting worms. Here, the worms do the turning and the aerating and the worm poo is loaded with minerals and unique micro-organisms that make this a truly champagne compost. There is always a downside, however, and here it relates to the lack of a heating stage during composting. Weed seeds and stable pathogenic spores can become an issue depending upon the feedstock that is utilised. Raw feedstock can be pre-composted to overcome this problem, if it cannot be eliminated with the choice of raw materials. The “worm juice” (residual liquid from watering the pile) can be collected and used as a potent liquid fertiliser/bio-inoculum.
Vermi compost is the most effective compost available. It can be highly productive at just two tonnes per hectare. In fact, comparative research at the now defunct, Gatton Field Days, revealed that vermi-compost was around twenty times more potent than composted cow manure (one tonne of vermi-compost was equivalent in performance to twenty tonnes of composted cow manure). Part of this enhanced performance is linked to the inoculum effect when using this product. The micro-organisms incubated in the worms gut are unique to these creatures and they offer an invaluable contribution to a soil lacking earthworms (most conventionally farmed soils).
If you can’t access vermicast or it is not a cost-effective alternative, it is always beneficial to build the number of native earthworms on your farm and there is a good strategy to achieve this goal.
Expanding Earthworms on Your Farm
Earthworms are little fertiliser machines that also aerate and improve soil structure. Earthworm counts in your soil are intimately linked to productivity and profitability and so there is great benefit in building their numbers. A great on-farm strategy involves allocating a paddock to earthworm production. This area should ideally contain a combination of legumes, grasses and cereals that should be slashed regularly to feed the worms. Ideally it should be irrigated and treated with humates and fish on a regular basis along with protozoa tea made from lucerne (protozoa are a favourite food for earthworms and Lucerne is jam-packed with these creatures). Earthworms can be easily transported from this haven to any areas on your farm that need rehabilitation.
The Work of the Masters
Beyond the broad definition of “active” and “passive”, there are several popular and proven composting techniques that warrant mention. Each of them originates from the work of some of the founding fathers of biological agriculture and they include:
- CMC composting – Controlled Microbial Composting is based upon Ehrenfried Pfeiffer’s work but was developed by Austrian, Ziegfried Luebke.
- Biodynamic composting – based upon Rudolf Steiner’s philosophy.
- Howard/Higgins composting – based on Sir Albert Howard’s work last century, which has recently been re-invented by UK consultant, Richard Higgins.
Guided Decomposition – CMC Success
Controlled Microbial Composting has become the industry standard for windrow composting in Europe and much of the US. This compost is heavily managed and monitored throughout the eight-week decomposition process and it has some unique features including the following:
- Clay or a clay-based soil is added at 5% to 10% to encourage the formation of a clay/humus crumb during the composting process. This is one of Luebke’s greatest contributions to the art and science of compost making, as it generates humus with a much greater longevity. A clay/humus crumb has a potential life of more than thirty years in the soil.
- The compost is inoculated with a special microbe blend on the second day and a previous compost is used as a starter, at a rate of 10%.
- Daily monitoring of moisture, temperature and CO2 is involved.
- When temperature is higher than 65 degrees celsius or CO2 exceeds 10%, the compost is turned to reduce both temperature and CO2.
- A moisture level of 50% to 55% is maintained throughout.
Steiner’s Master Work
Biodynamic composting is a centerpiece of the BD approach and, as with most of Steiner’s concepts, it has several unique features. The most unusual of these is the required shape of the heap. The pile must be trapezoidal when constructed, which means it should have four unequal sides. The compost is activated with special biodynamic presentations made from herbs, including chamomile, stinging nettle, yarrow, dandelion and horsetail. Dung slurry is watered onto the carbon layer (the brown material) during the layering process. Hydrated lime is dusted on each protein layer (the layer of green vegetation).
The Howard/Higgins System
Sir Albert Howard is widely regarded as the father of organic agriculture. While working in India early last century he developed the Indore approach. This approach, which is also appears to have inspired Steiner’s BD compost, involves a five foot (1.6 meter) layered stack, alternating greens, browns and animal manure. Soil and lime were sprinkled between each layer. Sometimes the pile was started inside a one-meter deep pit. The compost was only turned twice.
U.K consultant, Richard Higgins, is popularising the addition of wood ash, urine soil and clay to the original Howard recipe. Wood ash is a great source of potassium and the composting process stabilises this highly leachable nutrient. Potassium is so easily leached that a single rainfall event can remove the potassium from bonfire ash and return it to the soil. The key here is to keep your ash covered until it is added to the compost heap.
Urine soil involves adding urine to a pile of soil beside the compost heap and adding that to the compost. Urine contains more nitrogen than poo and it would be a great resource for dairy farmers if they could utilise it in composting.
The All-Important Carbon to Nitrogen Ratio
The single most important factor in the composting process is to try to achieve the ideal balance between carbon and nitrogen within the pile. If this balance is not addressed, decomposition will be compromised because the organisms involved require a certain, minimum amount of nitrogen to enable the breakdown of carbon. The ideal carbon to nitrogen ratio for your compost heap is 30:1 and a nitrogen source may often be required to achieve this goal. A very simple starting point is to try to achieve two parts brown (carbon) to one part green (nitrogen). The raw ingredients you can source will determine your need for extra nitrogen. For example, sawdust has a C: N ratio of 500:1, so considerable nitrogen will be required to compost this material. Easy to use C: N calculators are available on the web to simplify your decision making. Grass clippings and animal manure have a similar C: N ratio of around 20:1, so they will help in the decomposition of inputs higher in carbon.
The Two Heat Stages and Getting Them Right
The first stage of composting (the first one to two weeks) is called the thermophilic stage. This is where high temperatures are reached and organic matter is broken down by heat loving organisms producing gums, waxes, lignins, sugars and amino acids. Temperature should be monitored during this stage to ensure best results. The temperature must exceed 57 degrees C for at least three days to kill weed seeds and pathogens. The temperature should not, however, rise beyond 65 degrees C as carbon can be ashed and beneficial microbes will die.
The second phase is called the mesophilic stage and here we see temperatures reduce and oxygen increase. New groups of micro-organisms now move in and colonise the compost and bind the lignins, sugars and aminos into stable humic substances.
Bacterial or Fungal Dominance
Some crops are fungal dominated and they will prefer a fungi-dense compost. Orchards, vines and timber plantations are examples of these fungi-loving crops, and berries (including strawberries) also fall into this category. A simple recipe for a fungal compost involves 5% manure, 50% green and 45% brown.
Pastures, vegetables and most other crops prefer bacterial domination. This involves 25% manure, 50% green and 25% brown. If you compare these recipes you will recognise the fact that bacteria love nitrogen. This is because their bodies have the lowest C: N ratios of any creature on the planet. Bacteria have a C: N ratio of just 5:1 (their bodies comprise 17% N) while fungi have a C: N ratio of 20:1.
Moisture content is critical to microbial action. Moisture can be added when the pile or windrow is being built or during turning. It is essential to monitor moisture levels. Ensure that handfuls are taken from around and within the piles to identify and avoid wet or dry spots. A lack of consistent moisture throughout the heap can often be related to how the water was applied and how well the compost was mixed. The goal is to achieve a mix that, when squeezed, will only drip a couple of drops (like a wrung sponge). This represents less than 60% moisture. It is a good strategy to test the moisture content of any compost product before purchase to avoid the additional transport charges involved in carting wet compost.
Enriching Your Compost
There are several ingredients that will boost the fertilising and supportive power of your compost and they include the following:
- Zeolite – This natural mineral has a remarkable honeycomb structure which can serve to store minerals and moisture while housing beneficial microbes. It lasts indefinitely in your soil and effectively provides a third storage system (beyond humus and clay). Zeolite is typically added to compost at a rate of 6%.
- Raw humates – Brown coal is a tremendous compost additive as the composting process can release the humic and fulvic acids so densely present within this natural material. Do not exceed 20% brown coal or you may encounter problems with achieving the ideal C: N ratio in your compost (brown coal can contain as much as 60% organic carbon).
- Soft rock – If P is required in your soils this can be a good option. Some of the phosphate, calcium and silica in this product can be released during composting and the clay component of this material is ideal to encourage the complexing of clay with humus. This complex greatly extends the longevity of the compost.
- Seaweed – This sea plant is brilliant if you can access the material, as it provides a wealth of trace minerals and some powerful growth promoters.
- Bone meal and cottonseed meal – These materials can be a good source of nitrogen to balance out your C: N ratio.
- Wood ash – This is a good source of potassium but, as mentioned earlier, it must be collected and stored (or covered) to prevent K losses through leaching.
Problems of Poor Compost
If you get it wrong or buy product from someone who got it wrong, there is a risk of introducing a number of problems onto your property. For example, if pathogens or weed seeds were not effectively killed off during the thermophilic stage, you may be introducing some unwanted intruders. If the C: N ratio of the end product is unbalanced, then there is a risk of nutrient tie-ups or drawdowns. Nitrogen drawdown can be an expensive oversight. Depending upon the choice of raw materials and the efficiency of the composting there may also be issues with nuisance odours, toxic leachates and heavy metal contamination. These are not common problems and they are all overcome with good management. However, it is a good idea to ask for a full analysis of any compost product you are considering to ensure that heavy metals, antibiotics and herbicides are not present. This is sometimes a problem with composts made from municipal waste. There are also some simple tools you can use to help determine compost quality.
Your nose and eyes are handy tools when deciding if a pile is fully mature. Financial considerations can sometimes drive commercial producers to market compost that is not fully completed. If you are producing your own compost there are no hard fast rules for maturation time. The length of composting can vary based on water, microbes, oxygen, temperature and composition. Here is what you can do to help you decide if your compost is ready:
- Take a sample from deep within the pile with one hand only.
- The material should be dark brown in colour rather than black (a black colour can suggest that the compost was overcooked).
- If the compost stinks, it is not ready and may require turning or you may need to modify your recipe for improved aeration.
- A slight ammonia smell may still be evident in finished compost but this may also indicate the need for more browns (carbon). It is always a good idea to check the temperature as a final guide if there is still a question mark concerning completion.
- The compost is ready when temperatures inside the pile are steadily dropping (less than 40 degrees C) and plant matter is mostly humified (amorphous). The compost should exude a strong, earthy, forest floor smell.
How Much Is Enough?
500 kg to 5 tonnes of compost per hectare serves as a powerful inoculum and promotant, but you can apply as much as 30 tonnes of compost if it is cost-effective to use it for nutrient replacement and fertilising. If possible, the compost should be banded to maximise the response in the root zone and cost effectiveness.
Compost tea is one way to get maximum bang for your buck but this only supplies microbes rather than stable nutrients and humus.
Composting, and the associated building of humus, is arguably the most important thing that any of us can do to help reverse climate change. Storing carbon in the soil is simply the most effective way to keep CO2 out of the atmosphere. Building humus levels with compost is also the single, most effective way to build fertility and profitability and farmers may soon be paid to provide this service (via carbon credits). This is the ultimate win/win situation and I believe that we may be at the dawn of a golden era of agriculture.