The Permacultivator - Journal of Cool Climate Permaculture
Home composting has been used for many years by keen gardeners and is now being encouraged as a means of reducing the amount of waste being discarded to landfill.
WHAT IS COMPOSTING?
Composting is a method of speeding up and controlling the natural breakdown of organic matter into a soil-like substance for use as garden mulch and fertiliser.
Use of compost on your garden will increase the water retention capacity of the soil, as it is the organic content of soil which retains water.
Nutrients from compost are released slowly throughout the growing season and are less easily lost by leaching than nutrients in soluble fertilisers. There is an increased ability for the soil to absorb rapid changes in acidity and alkalinity and to neutralise organic toxins produced by some plants.
HOW TO GET STARTED
A compost heap should be sited in a warm sunny spot with a northerly aspect. The sides can be built up with any available material - fence palings, galvanised iron, or even wire mesh. Bins which have an open bottom can be used and should be sited in a warm sunny area and in direct contact with loose soil to allow drainage, air flow and entry of earthworms and micro-organisms. Earthworms contribute to efficient composting. The size really depends on the amount of available organic material you have but to get fastest breakdown of the heap it needs to be about a metre in each direction. Turning the heap, say every six weeks, will speed up the process also. However, most Australian gardeners opt for the leave it for a year method and dig out the finished compost from the bottom of the heap as needed.
WHAT TO USE
Grass clippings, kitchen waste, paper wrappings, fruit and vegetable peelings, leaves, prunings (shredded), tea leaves and bags, indoor plants, coffee grounds, egg shells, manure, weeds, vacuum cleaner dust, hair and wool, cardboard, sawdust and WATER. Acidic plants like pines would need to be countered with sprinkled dolomite or agricultural lime.
To avoid attracting vermin it is wise to cover each new layer of household scraps with grass clippings, sawdust or leaves.
Dont use: Animal products (meat, fat, bones), plastic, large branches, waxy plant material, diseased plants, prunings of persistent weeds (like blackberry, wandering jew, ivy), plant seeds, underground stems.
RECIPE FOR SUCCESS
All organic material is largely made up of different proportions of carbon and nitrogen. For composting to work, the correct ratio of carbon to nitrogen is required. This ratio is about 25-30 parts by weight of carbon to each part of nitrogen. A rule of thumb is to mix four parts of soft nitrogen rich material such as grass clippings, weeds, fruit and vegetable wastes with one part of sawdust, shredded prunings, newspaper or dry leaves. To help speed decomposition, you can chop or shred all your kitchen and garden waste and include some extra nitrogen rich material such as finished compost, sheep or cow manure, blood-and-bone fertiliser, or urea. The herb yarrow is also a good compost starter and comfrey is a valuable addition to any heap. Grow both of these nearby.
Keep the heap nicely moist by watering in dry weather and covering in very wet weather.
Feeding earthworms in a wooden or plastic bin is another good way to make high quality compost from food scraps and there is no need for turning because the earthworms will automatically aerate the material for you. It is an especially good idea for people who live in units or flats who only have a small courtyard or balcony. The container should have a lid and holes to let the worms breathe and be about 90x60x45 cm high for the average sized family. Put pre-soaked bedding material such as animal manure and shredded paper to a depth of about 15-20 cm. Feed the worms anything organic (except citrus peel and onion) placed on top of or buried slightly in the bedding and replace as the worms consume it. As the worms digest the food the contents of the bin will become slightly acidic which will slow down the worm activity. To counteract this add a fine sprinkling of dolomite (available from your local nursery) with each load of kitchen scraps. You will not produce great compost for your pot plants but breed worms which can be put in the garden.
USING THE COMPOST
Finished compost has a pleasant earthy smell, few recognisable pieces of the original organic material and is a fairly uniform dark brown or black colour. It may be used as soon as the temperature has dropped below 40 degrees - usually 3-4 weeks after starting. The finished product can be either dug into garden beds for vegetables or flowers or spread as a mulch around shrubs and trees.
Any accumulation of organic materials will eventually rot down into organic matter. An efficient compost heap mixes suitable ingredients together so that the process is speeded up. Any number of structures can be used to contain the heap.
A compost heap is an intricate, complex structure, where all the individual components are inter-related. They are all responsible for the breakdown, both physical and chemical, of organic matter into humus. The micro-organisms that are responsible for heated compost are living things and for them to function well, they require certain conditions. These conditions include : NUTRIENTS, OXYGEN, WATER, WARMTH and a SUITABLE pH.
1. MICRO-ORGANISMS enter the heap with the raw materials and by contact with the ground. Adding small amounts of soil, finished compost, or worm casts will boost the population further. Different types of micro-organisms, are at work, at different stages. Generally, the temperature of the heap will determine which microbes are at work. Other micro-organisms or small creatures digest plant remains, then bacteria can act upon it.
ACTINOMYCETES (a higher form of bacteria), similar to fungi and moulds, help in forming humus. They are generally aerobic (need oxygen) and work best at mid-range temperatures, they cause the greyish dusty appearance of some compost. If numbers of actinomycetes build up they can inhibit the bacterial action, as they produce antibiotics. Damping the heap down, to lower the temperature or adding high nitrogen ingredients, to increase the temperature, will reactivate the heap. MITES breakdown the soft portion of plant material.
MILLIPEDES chew and digest tough material so that other organisms can process it further.
WORMS convert organic matter to plant foods, their fresh casts are richer in nutrients than soil : 6 X nitrogen, 2 X calcium, 3 X magnesium, 7 X phosphorus and 10 X potassium levels.
SLATERS eat tough material after it begins to rot.
CENTIPEDES eat smaller organisms in the heap.
FUNGI digest dead plant materials and work best at 21 to 24 degrees C.
ANTS only occupy a cool heap, they can make the compost richer by bringing in potassium and phosphorus.
You need to create a carbon to nitrogen balance of between 25:1 and 35:1 for the heap to function effectively. A chart showing general C:N levels has been included as a guide. By using a wide mix of ingredients should give you an acceptable ratio. If the ratio is not right you can add ingredients to it. High lignin compounds, contain large amounts of carbon eg straw, firm leaves and sawdust. They are "cool" ingredients, taking much longer to break down. The resulting compost is quite stable and lasts a long time in the soil. Such compost is great for conditioning the soil structure. "Hot" ingredients, eg manures and lush green grasses etc, have greater amounts of nitrogen and are lower in lignin, they break down quickly. They produce a smaller amount of finished compost which is more easily used by plants, therefore it should be added more regularly. A wide variety of different ingredients will ensure the resulting compost contains the maximum range of nutrients. Micro-organisms require proteins and carbon rich foods to provide energy. Nutrients needed include carbon, nitrogen, phosphorus, potassium and trace elements.
OXYGEN is essential for aerobic micro-organisms. Aerating the heap will increase the aerobic microbial activity and speed up the decomposition. Air can be incorporated into the heap in several ways: using pipes or layers of woody material to allow air in, turning the heap regularly, or physically pumping air into the heap. Anaerobic heaps, are oxygen depleted, they are smelly and very slow to breakdown. Turning the heap also allows carbon dioxide and ammonia to escape. If these gases build up they will kill the micro-organisms.
WATER levels need to be balanced against the air levels, a 50-50 balance is ideal. Excess water, fills the air spaces and creates anaerobic conditions. While insufficient water, will slow the microbial activity greatly. As the heap is built, each layer should be watered. As a general rule, brown ingredients (carbon rich) need more water than green ingredients (nitrogen rich). As the heap is turned, water may be added if necessary.
The TEMPERATURE in the heap will vary. A temperature of 65 degrees can be generated in 2 days. At any point the micro-organisms are evolving, as conditions change other micro-organisms take over. Psychrophilic micro-organisms work below 4 degrees C. Mesophilic micro-organisms are most active between 4 and 37 degrees C. They are needed to get the temperature up, so the thermophilic micro-organisms can begin the main decomposition. Between 29 and 54 degrees C most breakdown occurs, up to 71 degrees C the rate slows and over 71 degrees C the process stops. A temperature of 55 degrees C for 3 days, is needed to destroy parasites, faecal and plant pathogens.
The pH of the heap will favour bacteria between pH 6 & 7.5. Fungi work well between 5.5 & 8. Out side these ranges breakdown is minimal. An acidic heap can be limed, but some nitrogen will be lost, when ammonia is produced. Lime can be added as : DOLOMITE - calcium and magnesium carbonates, GYPSUM - calcium sulphate, agricultural LIME - calcium carbonate, or WOOD ASH which also adds potassium.
CARBON NITROGEN CONTENT
The table on the following page lists some common materials suitable for mixing a compost heap. More Xs the higher the levels of N or C .
Naturally this list is only a guide. The actual composition levels within material vary greatly. From the table Id try : twice the volume of horse manure mixed with sawdust, or similar amounts of garden weeds (2-1), seaweed (1-2), wheatstraw (3-0), chook poo (0-3).
|blood n bone||XXX||weeds||XX||X|
|cow manure||XXX||woody weeds||XXX|
|tomato plants||X||XX||deciduous leaves||XXX|
|manure/straw mix||XX||XXX||food scraps (variable)||X||X|
|legume plants||X||XX||horse poo||X||XX|
|seaweed (high trace elements)||X||XX||
An understanding of the compost making processes, will help to solve or perhaps even prevent production problems. Once the reason for the problem is identified it can be remedied.
UNBALANCED C:N RATIO will inhibit the proper functioning, slow heaps are usually to high in carbon and take much longer to breakdown, fast heaps high in nitrogen will breakdown to almost nothing.Adjusting the balance of ingredients will get it going.
HEAP NOT HEATING UP 1. not enough volume, build it bigger. 2. low in nitrogen, add nitrogen rich material like manure, comfrey.
SLOW HEAP may 1. be dry, use the squeeze test and water if needed. 2. need more nitrogen. 3. need aeration, the microbes may have used oxygen, turning should get it going again. 4. be loosing too much heat, insulate to reduce heat loss or increase the heap size.
HEAP THAT STOPS TOTALLY has run out of nitrogen, if still not broken down turn the heap adding nitrogen rich material.
VERMIN OR MAGGOTS are attracted to meat and the manure of meat eating animals. Remove the offending material, cover the maggots with soil and lime well the next day. Try to avoid adding these materials.
STRONG SMELL OF AMMONIA 1. too little air, turn the heap. 2. too much water, turn & add dry material. 3. too much nitrogen to begin with, add high carbon material or nitrogen absorbing clay. 4. too much lime or high calcium ingredients, eg.mushroom compost can often have a high pH. Not easy to fix, turn heap and add acidic material like leaf litter, pine needles or add some sulphur powder.
DRY HEAP water as you turn the heap, cover to reduce moisture loss. It takes a lot of water to wet out some ingredients, sawdust can cause problems if it is not thoroughly wet out as you build the heap.
SMELLY HEAPS are anaerobic, i.e. working without oxygen. They are usually too wet or need turning.Turn to add air and mix in dry material if needed.Large amounts of wet nitrogen rich material will also produce a smelly rotten mass eg fresh lawn clippings in a pile.
VALUE OF COMPOST
The N:P:K levels of compost cannot be compared directly with synthetic fertilizers. They do however, release the nitrogen and phosphorus into the soil at a rate that can be used by the plants. None is lost through leaching. The other important fact is that soils rich in organic matter, are fertile because humus helps to make nutrients more available to plants. Manure is not a balanced fertilizer but when composted it is balanced chemically and biologically. Generally a partly completed compost should be used as a surface mulch. The final breakdown, in the soil may draw nitrogen out, plants could experience a loss of nitrogen in the soil, until breakdown is complete. Sprinkle a little blood and bone before mulching with unfinished compost, this will prevent nitrogen draw down in the plants. Compost is of benefit to any soil at any time. In most situations it is difficult to keep up with the demand for finished compost.
J18 Winter 97
A healthy soil will produce strong plant growth, animals feeding on this nutritious plant material will in turn be healthier and more productive. These plants, and the animals that feed upon them, will in time create food for the soil, as manure, mulch and rotting organic matter. And so the cycle continues. Any damage to the ecological balance of the soil will affect the vigour and productivity of the plants growing in it, and ultimately the animals higher up the food chain.
There is little doubt that the health of the soil is one of the most significant factors in sustainable, productive farming, gardening and/or agriculture. A healthy soil is a complex, carefully balanced ecology, that is easily disrupted by the use of chemical fertilisers, herbicides and pesticides. Therefore any attempts to rehabilitate or improve the soil , should include strategies to encourage the levels of biological activity in the soil.
An article, in a recent issue of the ALTERNATE FARMER Magazine, looked at improving the soil ecology by encouraging beneficial micro-organisms in farm soils. Research in Japan in the last 10 years has led to the practice of adding micro-organisms to the soil. Commercial products are now available. Three concerns are raised over the use of these commercial products : 1. the cost, 2. the micro-organisms are not local and can displace the existing populations and 3. there is a fear that farmers may become dependant on the companies that produce these products.
The above concerns have been over come by a Korean farmer Cho Hangyu, who developed BOKASHI , or fermented matter. It is a product that facilitates the breakdown of organic matter, using locally occurring aerobic and anaerobic bacteria, yeasts, fungi and protozoa. Over 3,500 organic farmers in Korea now make this product and its use is increasing. It is cheap and easy to make, works under both aerobic and anaerobic conditions, speeds up the break down organic matter and improves the soil condition in a short time.
Soak a cup of rice in water for several hours, strain liquid into a glass jar, to a depth of 5 cm. The drained rice can be cooked and eaten.
Add 1 teaspoon of brown sugar, loosely seal the jar and leave in a cool dark cupboard for 7 to 10 days. When fermented it should have a ësweet or pungentí odour.
Add 500 grams of unprocessed wheat or rice bran to the rice water and mix well, it should be damp not wet.
Mix in about 50 grams of good garden soil, collected near the compost heap is ideal as it should have plenty of microbes in it.
This mixture is placed in a plastic bag, excess air squeezed out, then kept in a warm spot for 7 to 10 days.
The mix is then spread on a tray to dry in a shady well ventilated area.The finished bokashi should smell musty or earthy not rotten.
Once dried the bokashi should be stored in a cool dark place.
Bokashi is mixed into food scraps, 1 teaspoon to a good handful of material.
Use a bag or lidded bucket to seal out as much air as possible.
Keep topping up bucket, with food/bokashi mix until full. Then place aside for about a week.
This material is now ready to add to your compost heap or dig into the soil. While it still looks quite rough it will finish breaking down quickly. Wait two weeks before planting seeds or seedlings into ground treated with bokashi.
While the above recipe may sound complex, it is quick and easy to do. From my personal observations the use of bokashi does speed up the breakdown of kitchen scrapes and I have added some to the compost heap to see how it goes. With winter fast approaching now would be an ideal time to boost our populations of soil microbes so that our composting rate is increased.
While all of this sounds great it does leave me with a dilemma, between the chooks, the worm farm, the traditional compost bins and the bokashi bucket I have a shortfall in organic waste!!
J17 Autumn 97
[Although Permaculture advocates the simplicity of home composting, there is clearly a better solution to current landfill practices. There will be need for this green technology for some years yet to come. Ed]
It is generally accepted that municipal solid waste consists of approximately 50% of green and putrescible waste. If paper were included, 75% of the total waste collected by Councils could be composted. This would reduce the volume of waste going to landfill by 75% to 85% and lead to a considerable saving in landfill space requirements. The removal of the compostable portion of the waste also improves the quality (performance) of the landfill in that it shortens the time before a landfill becomes stable, eliminates most of the landfill gas emissions and reduces considerably the post-closure problems of landfills.
The Annual Report 1996 of the Waste Service NSW reports that the first large-scale garden-and-wood waste composting facility commenced operations in June 1996 at the Eastern Creek Waste Centre. The contract to operate this facility was awarded to Australian Native Landscapes, a company which has operated their own composting facility near Penrith for some years, an operation which has been commercially very successful. The operation is based on source-separated feedstock.
Later this year Waste Service is planning to open another composting facility at the Jacks Gully Waste Management Centre at Camden. Two further composting facilities are in the planning stage. The Report further mentions a Bio-Waste Treatment Facility to be operated at the Chullora Recycling Park to treat food, and other organic waste, in an enclosed environment. The aim is "to produce a high quality compost for sale into the landscaping and topsoil replacement markets." Regrettably details of the operational process are not available yet.
Another joint research project in which Waste Service NSW and the Co-operative Research Centre for Waste Management and Pollution Control (CRC) are involved is an investigation of the "enhanced breakdown of solid waste in an enclosed environment. The project aims to retain the nutrient value in mixed waste and to convert it into a valuable and marketable product such as a slow-release fertiliser."
We would like to think the establishment of municipal composting facilities and the various research projects into the biological conversion of organic waste into soil-restorative compost is good news for the Australian Environment, threatened as it is by ever-advancing land degradation. However it is only a beginning, yet it is heartening to see the SERRG already planning to set up their own composting facilities.
What will be absolutely critical for the success of the budding compost industry will be the need to establish tight quality standards to achieve market acceptance.
Whether to be used in horticulture, viticulture, landscaping or agriculture, compost will only find ready acceptance if it can be produced to standards meeting the following criteria:
* It must not present any health hazards
* It must be a valuable plant food and humus producer
* It must be free of impurities and noxious substances
* It must have a known proportion of beneficial properties
* The product must be consistent in quality and give a visually attractive overall impression.
Extensive research and many years of practical production and marketing experience overseas have shown that compost quality is determined to a major degree by the type and composition of the feedstock as well as by the process techology and decomposition technique. Compost produced in the early days of the industry did not have a good reception because it used co-mingled Council wastes as feedstock. It has been clearly established that in order to produce compost of consistent top quality, source-separated organic waste must be used as feedstock.
Co-mingled municipal garbage contains not only high levels of extraneous material such as glass, plastic and metal but also significant uncontrollable proportions of noxious substances. Test results published by the Minister for the Environment of the State of Rhineland-Palatinate (Federal Republic of Germany) shows typical heavy metal concentrations (mg/kg dry weight) in compost produced from source-separated feedstock (household organics and green waste) and mixed waste respectively. The source-separated organics produced compost well below the official German limits, while mixed waste compost far exceeded them (Funke 1992 p. 12.] The Australian Draft Standards compare favourably with the German standards.
Some composting systems involve the addition of sewerage sludge during the production process. The product known as sewerage sludge is not homogenous. For example, from just two sewage treatment plants (Glenfield and West Camden) there was up to a five-fold variation in the concentrations of individual metals within a plant and up to a seven-fold variation between plants. Clearly, concentrations of both nutrients and pollutants must be known. Individual batches of sludge must be assessed for their suitability for compost admixture.
The greatest risks in sewage sludge come under the headings of pathogens, heavy metals, organic pollutants and nutrients. Sludge contains hevay metals such as arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel and zinc which can be toxic to animals and plants. Bacteria comprise the most numerous pathogens found in sewage sludge. Although some bacteria can be killed (in compost additions) by the thermophilic phase, others can survive and reproduce in sludge for several months. Clostridium perfringens and Salmonella, both of which cause gastro-enteritis, are considered to be the most persistent bacteria. Protozoans that may be present in sewage sludge include Giardia and Cryptosporidium. The latter was recently even isolated in Sydney Water storages. They can be killed when heated to 53 degrees Celsius for at least 30 minutes or by storing for 4 months at ambient temperatures.
While considering the establishment of municipal composting, some Councils seem to prefer systems using co-mingled Council waste as feed stock for compost production as it appears to obviate the need for a separate landfill facility. However, Councils would want to ensure they would be able to recover their substantial investment in the establishment of a compost plant. The surest way for this to occur would be to produce top quality compost. Once Australian Compost Standards Quality Classifications are developed and a compost market has been established, the quality of the product will obviously determine the price levels for the various classifications.
Another important decision Councils, particularly in areas of low population density, will have to make is whether they can operate a compost facility on their own or whether they will have to join with other local government area(s) to make such a facility viable. Economic viability starts with an annual throughput of between approximately 10,000 to 15,000 tonne per annum. Overseas experience indicates that the decomposition methods used on centralised (large) compost facilities entail significantly higher capital costs than do those on de-centralised (small) compost facilities.
The choice will also be influenced by the level of transport costs and transport vehicle emissions to and from centralised or decentralised sites. In general, source-separated organic wastes can be composted with far less technical outlay than is the case when co-mingled waste is being utilised as feedstock, in which case the product-specific technical outlay is considerable. This makes it possible to plan for smaller facilities which could share equipment such as comminuting units, re-stackers and screens available in mobile versions. This more intensive utilisation of expensive machinery would reduce site-specific costs, an advantage in less densely populated areas.
The sceptics are now telling us that the "worry is that if all Councils collect and compost all green waste tomorrow, well have compost coming out of our ears and we wont be able to use it." (Sue Dawson, NSW EPA). Even people who ought to know better seem to delight in negative comments.
One would have to be blind not to see the unique opportunity of millions of tonnes of city-generated soil restorative compost being available on an ongoing basis year after year to meet the ongoing crisis of advancing land degradation. It would be safe to say that governments cannot continue for much longer to react to this crisis on a piecemeal basis and that any broad-based land degradation remediation scheme would need the operational and financial support of governments.
It would seem that markets for country-generated compost would not be as difficult a problem as the sale of large supplies of city-generated compost, particularly if compost production in country districts were based on de-centralised facilities. Transport costs should be appreciably lower as the compost would be dispersed locally. Compost sales to horticultural and landscape users seem already to be fairly healthy and the supply for agricultural users for the remediation of land degredation would have to be integrated into a State-wide scheme.
J18 Winter 97