SECTION 2. A compilation of original information which we have developed to explain various practical subjects related to local organic food growing activities and issues.
1. COMPOST: WHAT DOES IT MEAN?
An article written for the Community Composting Network in 1997, attempting to establish straightforward labelling to describe compost produced for sale
The word "compost" has a glamour or kudos all of its own, charged with quasi-mystical potency by those few initiates who have witnessed its effects; occult alchemy to most, ignored by society at large.
However, this humble concept could hold the key to solving some of modern civilisation's more intractable problems, such as waste disposal, contamination of food cycles and the increasing ineffectiveness of anti-biotics.
Modern usage for the word and the process it describes date back only about 100 years in the western world, although there are examples of the indigenous practice of composting throughout history and pre-history, especially the continuous tradition of composting techniques in China.
Etymologically, the word is derived from the French compot, a mixture or composition. As a verb, there are a variety of definitions and descriptions of the process: The aerobic decomposition and reconstitution of organic wastes into humus by the action of micro- and macro-organisms, involving the bonding of
nitrogen onto carbon molecules, fixing proteins and carbohydrates in forms readily available to plants. The word compost is now used as a generic term to describe any growth medium. As the collective name used to refer to a diverse range of different products and processes, compost can be a confusing and misleading term.
A stricter and more accurate use of the word would perhaps be to describe compost by its humus content. Humus compost is a distinct and superior product when compared to many other growing media, which should really be sold as such on its own merits.
Garden compost, potting compost and fine seed compost all have distinctive and separate uses and are not interchangeable. The infinite diversity of composts can be classified variously: according to the inputs to the process or source of materials, such as garden, domestic, municipal, industrial or agricultural: or by the end-use for which the medium will be used, such as for seed, seedling, potting on, potting up, cuttings, acid [ericaceous] or alkaline, special mixes for indoor growing, high-fertility for heavy feeders and formulations for specific types of plants such as cacti. Garden composts containing different manures will result in a variety of different properties suitable for specific types of crop. Concentrated fertilizers [organic or chemical] can be added to create quick-acting or slow-release mixes. Different production methods also generate specific qualities in the end-product, such as stacking, windrow, pit or vermiculture [worms]. Less accurately, the word is even applied to related processes such as loam-making, the formation of leafmould and even the anaerobic putrefaction of liquid wastes in cesspits and settling tanks [slurry].
The promiscuous application of the word compost to so many different materials means that anyone engaged in selling a compost product must label it explicitly and comprehensively to avoid inappropriate use. It is necessary to
explain what ingredients the material consists of, where the inputs were sourced from and how it can be expected to perform.
Most importantly from the perspective of growing organic food, it is necessary to explain whether the product is suitable for food use or whether it is only fit for non-food use in ornamental gardening. Accurate trades description of products means that customers will be less likely to use them in inappropriate contexts and will therefore be more likely to be satisfied with their performance and trust the producer with further business.
2. RECOMMENDED METHOD FOR MEDIUM SCALE COMPOSTING
[Suitable for 1,000 Kg per week producing 25 metric tonnes of mature compost annually]
For the past ten years, the Ecology Company Compost Collective has had access to a regular supply of vegetable waste from Beanies Wholefood Co-operative in Sheffield. This source provides between 300 and 500Kg of matter per week, collected in 12 ordinary domestic refuse bins, supplemented by donations of compostables from local residents. Beanies provide transport [van + driver for 1 hour per week] and the waste is delivered cyclically to twenty sites, a total of five acres of cultivated ground. In return, Beanies save the rental of two or three trade waste bins, 500 to 750 L capacity, which would otherwise cost £250 per year each. A small proportion [5-15 %] of this material is directly from certified organic sources, but most is conventionally grown.
Composting areas 4-6 square metres in area, with a base of clay and loam, are edged on two sides by large sheets of marine plyboard [1.5m/5 feet high], set at a right angle. This space can be subdivided by moveable boards to create three-sided compartments to accommodate variable volumes from 1 to 8 cubic metres. This is useful since when composts reduce in volume, they can be re-stacked to take up less space. A depression in the ground directly in front of this area forms a collection pit for any nutrient-rich liquid which leaches from the heap and can be returned to the hot, dry top of the heap. These pits are covered by wooden chopping boards [5cm/1.5 inches thick; 50-70 cm square] which facilitates chopping of inputs.
Each week, heaps are constructed between 1 and 3 cubic metres in volume, depending on the availability and density of other materials combined with the vegetable waste. Except for transport, no machines are used in this scale
of composting, since their costs and logistics would be prohibitive, and they increase danger of accidents.
Three types of bulky material are included in each heap in approximately equal measures:
VEGETABLE WASTES. Chopped into 3cm square pieces with a sharp spade.
GARDEN WASTES. Crop residues, annual weeds, hay and straw. Chopped if necessary. Structural material.
MANURES. Cattle or horse. Introduce digestive bacteria and influence the nature of the end result.
In addition, a variety of more concentrated sources of fertility are added: seaweed, rockdusts, magnesium lime, activators [urine, comfrey and nettle teas]. In addition, the heap is inoculated with small amounts of topsoil, mature compost and populations of eisenia foetida and their eggs to ensure the presence of abundant micro- and macro-organisms to digest the raw materials.
This diversity of inputs guarantees that the conditions for efficient composting are present; aeration or ventilation, moisture cycling by evaporation and condensation, and insulation to help the thermophilic bacterial reactions which
achieve the initial breakdown of the inputs.
The three forms of bulky organic matter, as above, are alternately added to the heap in layers 10-20 cm/4-8 inches thick. Additives are distributed over these layers as the heap is built. The base of the heap [the first 50cm/18 inches] consist of porous matter which will soak up liquid draining down through the heap and structural material [such as woody stalks], which permit air to be drawn into the lower half of the heap. Care is taken to flatten the layers progressively to maximise the horizontal surface area, which produces a firm sheer vertical edge on the fourth, open side of the heap, allowing it to be built up higher [1.5m/5Ft] than if it were built at an angle. The last cycle of layers can be used to form a dome-shape at the top of the heap, shaped in an inverted parabolic curve, to facilitate the re-distribution of condensed evaporation back into the heap. Materials which are harder to digest [such as weed roots and seeds] are included in these upper strata where they will receive most heat and be effectively cooked. The heap is covered with three coverings: a layer of paper or card which will absorb evaporation, a layer of plastic sheeting to prevent moisture escaping from the heap and a piece of natural fibre carpet or underlay to retain heat within the heap.
Heaps are turned at least three times at 2-4 week intervals, by chopping vertically through the horizontal layers formed when the heap was made, slicing through with a sharp spade every 5cm/2inches. This effectively re-distributes the materials and generates a second flush of heat and bacterial breakdown. After two moths and one turning, the individual materials included at the start are indistinguishable and this raw compost can be used as mulch or for perennials or for heavy feeders like squash, tomatoes and runner beans. If the heap is re-stacked further, the aim is to invert it inside-out and upside-down [outside-in and downside-up],which will produce a fully homogenised mixture and allow macro-organisms to uniformly improve the material further. After six months, the compost is stable enough to be incorporated into the soil and mature enough not to contain pests or diseases.
At this age, any residues which might have contaminated the input material will have been digested and neutralised, and the compost can be considered fit for inclusion within a strictly organic growing system.
Six-month old compost has also reached a stable volume, approximately a quarter of what it was to begin with, and can be stored in bags or containers to mature fully. Year old compost can be safely applied to any vegetable crop at
almost any stage of its growth and is also now fit for more sophisticated uses, such as in potting mixtures or houseplant mixes.
Ecocococo produces approximately 25 tonnes of finished organic compost each year, used for growing organic vegetables, fruit and herbs. The following overleaf has been used as a leaflet to advertise this project for the past seven years.
3. COMPOSTING IN CROOKESMOOR
Have you ever thought about recycling your vegetable waste? Up to 1/3 of the volume of domestic refuse is organic matter which can be recycled to feed plants and soil. This is much more ecological than incineration, which is where your bin bag ends up and separating this matter keeps your regular bin clean and free of unpleasant smells. The Ecology company and Beanies have been composting shop and domestic vegetable waste on local allotments for more than eight years. If you would like to recycle more of your rubbish and make more gardens greener, simply collect all the ingredients listed below in a carrier bag or plastic bin and bring them to the Ecology Company or place thein the special bins in the yard round the back of the shops.
« If you have large amounts of single materials
(eg leaves/sawdust) please deliver them bagged separate from the rest of the waste.
« If you would like more information or advice on how to compost your own domestic waste, please ask at the Ecology company (Tel 267 1200).
« If you have a large garden or allotment and would like a load of vegetable waste to add to your compost, we may be able to deliver some to you free of charge.
FRUIT AND VEGETABLE WASTES AND PEELINGS
FOOD SCRAPS AND LEFTOVERS (INCLUDING BREAD AND EGGSHELLS)
TEA BAGS AND TEA LEAVES. COFFEE GROUNDS AND FILTER PAPERS
FLOOR SWEEPINGS AND VACUUM CLEANER DUST (IF FREE FROM CONTAMINANTS)
HAIR (HUMAN OR ANIMAL) / SHAVINGS / FEATHERS / NATURAL FIBRES (WOOL/COTTON etc)
AUTUMN LEAVES / GRASS MOWINGS / ANNUAL WEEDS / DEAD HOUSE PLANTS
PET LITTER AND BEDDING (NOT CAT OR DOG)
WOOD ASHES / SAWDUST / WOOD SHAVINGS / PAPER / TISSUE PAPER / KITCHEN ROLL / LOO ROLL
COMPOST INGREDIENTS
SMALL AMOUNTS ONLY OF:
N CONTAMINANTS N
Please do NOT include any of the following:
PLASTICS / METALS / GLASS / PAINT / CHEMICALS / COSMETICS / DETERGENTS /
TOBACCO / WOODY HEDGE CLIPPINGS / PERENNIAL WEEDS
If you are throwing out any of the following we would be happy to put them to good use helping
local allotmenteers:
OLD PLANT POTS / OLD GARDEN TOOLS (MENDABLE) / WOOD GUTTERING / TIMBER
/ GLASS PANES IN FRAMES / OLD CARPETS (WOOL AND HESSIAN,
NOT SYNTHETIC FIBRES) THANK YOU
4. HEELEY CITY FARM COMPOSTING OPERATION.
A report by Richard Clare, assessing the composting scheme at Sheffield's city farm, compiled after a visit in August
1997.
Following a visit in August, I have compiled a brief , critical and hopefully constructive summary of the current state of the project and included basic recommendations for its improvement.
My motivation is that the HCF composting operation has a high public profile and should therefore be a demonstration of best practice, for the benefit of the farm itself and the general public it serves. I would hope that this advice is noted and acted upon where and when possible. I would be happy if this document is used to aid lobbying for upgrading the system and would be willing to co-operate further if required..
The main perameters of this survey are to minimise wasted time and energy and to maximise the quality and usage value of the end product.
I am concerned about the reputation of compost and wish to promote a positive profile. My qualifications to make this assessment are that I have co-ordinated a composting operation based in Crookesmoor and Crookes for the past nine years, now producing 25 metric tonnes of food-growing grade finished product annually. I have also actively attempted to promote this and related issues such as organic horticulture, leafmould, recycling and the health and educational potential of these subjects.
CURRENT INFRASTRUCTURE AND PROCESS.
GROUND AREA; 5 x 6 m = 30 m3 [20 x 25 Ft]
Time and effort are at presently being wasted because of inefficiencies in the structure of the composting area. If the concrete block dividing walls were largely removed, the turning of the heaps would be facilitated and variable-
sized heaps could be accommodated more easily. These walls should be replaced by moveable sides made of inch-
thick marine plyboard.
The concrete path down the middle of the working area is fine to permit access in all weathers, but is not a suitable surface on which to compost. Similarly the rubble and compacted clay base under the binspaces could be improved by breaking up the subsoil and importing a six inch [15cm] layer of good quality loam from soil under cultivation. This would achieve a much greater uptake of air from beneath the heaps and permit compost worms [Eisenia foetida] to
migrate from maturing to fresher material. This measure would also help to minimise leaching, since any leachate would be consolidated into the loam, which could be dug out and replaced on an annual basis to provide a supercharged loam when returned to growing areas.
ONSITE INPUTS; MANURE AND BEDDING FROM ANIMAL STALLS.
These provide a good initial diversity derived as it is from a wide variety of beasts, although excessive amounts of carbon are present in the form of sawdust and woodchip. Additional materials such as crop residues in season and occasional vegetable wastes from the cafe and local domestic sources are also included in the mix.
From an organic viewpoint, these materials are contaminated by the inclusion of chemical fertiliser pellets [Osmacote]derived from spent potting composts from the garden centre. These are presumably used to compensate for the inadequacies of the COIR-based media currently used. Exclusion of this fertiliser would give the end-product more genuine claim to be of organic standard. In the long term, a switch to more soil-based media, eventually with leafmould substituting for coir or peat , would help to achieve this aim. It should be noted that many of the plants sold are herbs and native wild species which have no need for high levels of fertility, which can actually be detrimental for example in the case of culinary and aromatic herbs.
INPUTS FROM OFFSITE; SPENT HOPS FROM LOCAL BREWERY.
Like any other material, this is difficult to compost without dilution with 3 to 4 times its volume of material which will balance its particular qualities. Unfortunately, hops are very close in nature to the woody bedding which has already
been identified as being excessive in the present mix. They release a flush of nitrogen which must be used to reduce the high carbon and cellulose content of the raw material. Unless sufficient suitable material can be added, the hops may be best composted seperately to produce a mulch. Addition of nitrogen in liquid form would enhance their breakdown and may help to reduce the unpleasant smell often associated with them.
RECOMMENDATIONS.
1. It is vital to source and import much more green matter, vegetable and putrescible wastes, shredded garden waste and grass mowings etc. An amount of such material two to four times the volume of manure and bedding could be successfully digested. Sufficient input of these types of material would provide a better initial carbon-nitrogen ratio. Sources of slowly released moisture and nitrogen from within the heap would help to digest the woody content, simultaneously moderating the vigour and extending the length of thermophilic bacterial heating.
2. The current mix of inputs does not provide sufficient structural material to allow circulation horizontally and vertically around the heaps. Tubular cellulose material permits oxygen to be drawn into the heap without the effort of turning. Such materials as brassica stems and stalks or even current year growth hedge prunings may take 6 months to break down but would improve the process and the end-product.
3. Steps could be taken to improve the recycling of moisture within the heaps. If the top of heaps forms a dome shape [ideally an inverted parabola] , water evaporating from the heat at the centre of the pile will recondense when it rises to the top of the dome and trickle down inside the covering to remoisten the heap. This would also reduce the amount and frequency of watering required. Present coverings are permeable plastic tarpaulin which allow water and nitrogen to exit the heap in the forms of steam and ammonia gas, creating a risk of denitrification [the loss of nitrogen from the heap]. The combination of the dome-shape and use of impermeable plastic covers would help to recycle water and bond available nutrients.
4. Insulating layers of carpet are efficient, but could be changed to natural fibres instead of man-made/synthetic materials. Wool and hessian carpets or carpet underlay should be sourced since they do not desiccate to contaminate the compost , but instead break down yielding high levels of nitrogen and can be added to the compost mix. When synthetic materials do become unserviceable they present a waste disposal problem.
5. Current inputs have the potential to produce finished material of food-growing quality, fit for human consumption, if the imbalances in the initial mix are remedied. This goal could be further helped by the addition of a wide variety of fertilising agents, which together can guarantee the end product will perform well enough to meet the high demands of most food crops. Some suggestions are listed here with brief comments on the improvements they contribute.
SEAWEED; Gelling agents promote the retention of moisture and nutrients in forms available to plant roots. Contains many soluble trace elements often leached out of soils at high altitude [as in Sheffield].
ROCK DUSTS; VOLCANIC etc. Contain wide spectrum of trace elements that are usually slowly released but can be quickly dissolved in the acidic composting reaction. Suitable for composts for enduring growth and long-term performance.
MAGNESIUM LIME [e.g.DOLOMITE] Predominantly useful in small amounts to feed bacterial reactions in the early phases of breakdown but is also vital for chlorophyll metabolism in plants.
HIGH NITROGENOUS FERTILISERS [e.g.BLOOD FISH AND BONEMEAL/HOOF AND HORN]
Soluble fertilisers would help to balance the carbon-nitrogen ratio and slow-release would improve the value and range of uses of the finished product.
MARKETING. Maximum values can be obtained from the product by ensuring it will satisfy the customers' needs and expectations. To this end, the material should always be fully mature [6-9 months old at least], requiring a backlog surplus to be built-up. When fully ripe, the moisture content of the material will naturally decrease unaided by sun drying, which is a test of its ripeness to the experienced eye.
The leaflet produced to promote the material is commendable although it would confuse many readers into thinking they were buying an organic product due to the profligate use of that term in the text. The issue of trades description is crucial to providing accurate information to buyers about what uses are appropriate for the product. If customers are satisfied, they will return and generate a good reputation which will help to guarantee the long term security if the project. Samples of product on sale in August showed signs of being a woody mulch which could cause denitrification and consequent stress to plants if incorporated into the soil.
ADDED VALUE. The more processing and improvement and the greater variety of end-products produced, the greater will be the profitability of the operation. For instance, special potting composts for specific uses command higher prices than the unrefined output. Also, greatest financial return can be gained from a limited throughput by post-processing; growing herbs, flowers and vegetables using the material.
FUNDING. As a business proposition, even large scale, mechanised setups would find it difficult to remain viable competing against the abundance of products already available in the mass market, even if they were distinguished by organic certification. Although commercially marginal, projects are socially and ecologically justifiable in themselves. However, recent official incentives to encourage the proliferation of composting are related to the mass and volume of waste material they can extract from mass waste streams, saving valuable landfill space [and tax] or in the case of Sheffield diverting material which is 90% water from the incinerator.
Action to intercept larger amounts from the green [putrescible] waste stream would be likely to be seen favourably by fund distributors and could provide the basis for expansion of the project .
5. ORGANIC MATTER RECYCLING REPORT
The following report was submitted to Sheffield Council's Recycling Officer, Stuart Hodgkin, in 1991. Much of it is still relevant and Sheffield currently has no means of recycling the organic fraction of its waste.
1. PRESENT SITUATION.
The estimated weight of putrescible organic matter waste processed annually in Sheffield is approximately 40,000 Metric Tonnes [25% of the total wastestream, 160,000 tonnes]. Much of this material is currently burnt at the
Council's Bernard Road incinerator at a cost of £6 per M.T. Organic matter is unsuitable for combustion being made up of over 90% water, which must be evaporated before the remaining dry fraction burns.
The Environmental Protection Act 1990, provides local authorities with the statutory power to enforce source separation of any recyclable resource, where a means for its recovery exists. The E.C. target for recycling is to recover
25% of total waste by 1996. Although 68% of households in Sheffield make some effort to recycle, present estimates show that only 16% of total waste is recovered citywide.
It is reckoned that on average organic matter takes up about 30% of domestic binspace. Many individuals already compost their own waste organic matter on a garden scale. Sheffield Community Recycling Action Project has recently produced a leaflet explaining the composting process, to encourage more people to use this valuable resource. Heeley City Farm has run courses and field trials, successfully growing organic vegetables on brickdust subsoil using compost derived from domestic collection. The Ecology Company's Compost Collective currently produces 20 tonnes of compost per year on 12 allotment sites, recycling vegetable waste from greengrocers in S10.
Although Sheffield's economic history is predominantly industrial rather than agricultural, there has been a strong and continuous horticultural tradition in the area, in private gardens and the 3,000 allotment plots, on 66 sites covering 350 acres. Sheffield is uniquely well-provided for in the area of greenspace since the city itself covers an are of 36,00 hectares. However, organic matter must usually be obtained from rural supplies or imported from outside the region. Last year, the compost budget for municipal parks alone was £75,000. By diverting putrescible organic refuse away from the inefficient incinerator and converting it into compost, the city could save and benefit from the nutrients it contains. This form of recycling would make Sheffield a literally greener city.
Several cities around the world have already begun to recognise the value of their organic waste resources and acknowledge the ecological importance of re-using this resource. Composting is most suitable for urban areas where population is dense and local opportunities to recycle organic matter are limited Some schemes are operated as high-technology, capital-intensive, centralised operations, using industrial-scale waste digesters such as the Dano processors [e.g.Munich]. Others are run using low or intermediate technology, as local community amenities
[e.g.Byker Tyneside], or as schemes to encourage and facilitate home-composting [e.g. Adur West Sussex].
2. RESOURCE INPUTS.
A wide range of industrial, institutional, retail and domestic waste materials can be recovered by composting processes. Some inputs are readily compostable, such as spoilt produce from shops and wholesale markets, spent hops from breweries and fruit and vegetable wastes and peelings from homes, hospitals, schools and other food processors.
Some inputs are valued as fertilisers, such as abattoir products, manures, pet and poultry litter, wool shoddy from old carpets and mattresses, hair clippings from barbers and urine [piss]. Many other materials can be added to compost, either to improve its texture, such as rotted sawdust or shredded cardboard, or to add minerals, such as coffee grounds, gypsum plaster and basic slag from kiln linings. A variety of contaminants, such as metal and plastic packaging, glass, chemical residues and colour inks must be removed from the inputs by separation before processing and also by screening the finished product.
Citywide collection of available inputs could be achieved by a variety of complimentary methods, ranging from large-scale high volumes, delivered to a centralised composting site, to local collection rounds and domestic composting units. Information on inputs and sources would need to be databased and mapped to enable efficient collection to take place.
3. PROCESSING.
Compost can be processed either in heaps or in long rows. The process is improved by aeration, moisture control, insulation, microbial inoculation and by introducing specialist compost worms [Eisenia Foetida] to refine the material into a mature finished product. Initial decomposition by micro-organisms generates heat [up to 65 degrees C], water vapour and carbon dioxide, and persists for 2-4 weeks. During this stage, the volume of the material is reduced by about a third, facilitating storage. This material is then matured into stable, homogenous, humus-rich ripe compost by the action of macro-organisms, a process which can take up to six months. The essential chemical action of the process is the bonding nitrogen onto carbon, which can be achieved most efficiently if these elements are combined in a suitable ratio, ideally 35 parts carbon to 1 part nitrogen. In the mature compost, this carbon-nitrogen ratio is reduced to 10:1, at which level, nitrogen is safely and readily available to plants.
The logistics of a composting operation are decided by the volume and frequency of inputs. This supply is subject to seasonal and other cyclical variations. Mature compost can be obtained in as little as six months, using an area of
1 sq. metre to process each metric tonne of inputs/output. A site used for composting would have to be managed to ensure efficient reception, processing, storage and despatch of materials. It would also have to meet environmental
and health and safety requirements. In addition, attention should be paid to site ecology to ensure that the sight, sound and smell of the process are not offensive to public opinion. The end-product should be monitored and tested regularly for its pathogen and heavy metals content.
Any large-scale composting scheme would benefit from the technical involvement and support of a wide range of disciplines. Locally, expertise, facilities and information are available from Cleansing Services, Sheffield University and Polytechnic. Nationally there exists a large network of organisations and initiatives in this field.
4. COSTS.
The start-up costs of a composting enterprise using low/intermediate technology would be very small relative to the impact it could make on the total volume of wastes recovered.
Capital expenditure would be required for site-preparation, machinery and transport, although existing facilities and plant could be adapted at minimal cost. The site would need a road and drop-off point suitable for large lorries delivering fresh garbage. Chopping and mixing machinery appropriate to the scale of the operation would be essential for the initial preparation of materials for composting. Building and turning small volume heaps can be achieved efficiently by personpower using basic tools, though other machines such as front-loading earthmovers and conveyor belts would greatly increase the rate of processing larger volumes. Suitable transport would be required for the collection of raw materials and for the delivery of finished compost. Safety and monitoring equipment would also be necessary.
Operating costs would largely be expenditure on wages. These would vary in proportion to the volume of organic matter available for processing. Other running costs would be minimal expenditures such as additives to improve the quality of the final product, such as seaweed meal or rock dusts, fuel costs and administration resources etc. Some costs could be minimised by using other recycled materials such as timber or pallets.
5. FUNDING.
A wide variety of funding opportunities would be available to a municipal-scale composting scheme. Environmental concern groups such as Friends of the Earth and Greenpeace are keen to support new ecological recycling projects. The City Council is committed to "encourage and develop domestic, industrial and commercial recycling initiatives and develop mini recycling centres throughout Sheffield; and encourage industry and business to adopt better management of waste through recycling." [Draft Unitary Development Plan 1991. SCC Planning Department] These aims could all be achieved by supporting and co-operating in composting projects. The council has mechanical resources and logistical expertise which could be made available to such projects on favourable terms
to the mutual benefit of both parties. Big business is aware of the potential economic benefits of recovering waste and retailing compost products. Several large concerns are currently offering help with finance and research and are keen to be involved in such projects.
In addition to these established sources of support, a composting scheme could use other creative methods of fundraising. For instance, donors of organic waste could be issued with shares entitling them to a proportion of the end-product. This form of credit would act as an incentive to the separation and collection of material. If the scheme was financially successful, these credits could even be redeemed for cash.
6. OUTPUTS.
The returns in profit from composting will be delayed by two factors. Firstly, the processing cycle from raw material to saleable product should take 6-12 months to complete. Secondly, the buying public may take some time to accept and demand the new product. However, a large market already exists for compatible products.
Trends such as organic gardening and the substitution of peat as a growing medium could put recycled organic compost at a premium.
The financial return from output can be estimated by comparing the retail prices of similar products. Stable manure costs 50p for 25 Kg [=£20 per Metric Tonne]. Peat costs approximately £4 for 50 L [=£80 per MT]. Growbags cost £1 for 20 Kg [=£50 per MT]. Fine potting compost costs £1 for 5 Kg [=£200 per MT]. Wormcasts cost £2 for 5Kg [=£400 per MT]. Different grades and mixtures of compost could be manufactured to supply these various markets.
In addition to the core products, there are also several by-products of the process which could also be generated, such as uses for the heat output and related products such as liquid feeds derived from leachate.
The potential value of these secondary outputs can be understood by reference to one specific product. A large demand exists for compost worms to use as bait for fishing. These can be sold for as much as £2 per kilo, a staggering £2000 per metric tonne. Since these potential returns may take years to be realised, it must be understood that any compost processing business could only reach break-even point and profitability in the medium to long term.
A composting enterprise would perform two services of benefit to the community; waste disposal and provision of compost products. Several other benefits could be derived, such as the use compost to help regenerate derelict allotment sites. Compost could be made available at a subsidised price to enable more disadvantaged people to grow their own fresh fruit and vegetables. It would be especially useful for elderly and infirm gardeners who may be less capable of making their own. A composting scheme could also provide opportunities for practical research in the field of biotechnology. A successful operation would have prestige value for Sheffield as an innovative example of resource recycling and improving urban ecology.
6. The following material was prepared as a leaflet to explain leafmould in February 1994, when it was created to accompany a display on the subject at a peat-free growing media conference, organised to promote the preservation of peatland in Sheffield. It seemed necessary to present some basic argument in favour and a simple, coherent and comprehensible explanation of the process. In spite of this being a national event, no-one else was promoting leafmould.
WHY LEAFMOULD ?
Trees are nature's soil builders. The floor of forests and deciduous woodland is often referred to as an ideal soil creation system, steadily recycling and accumulating plant foods. A mature tree produces several acres of leaf surface area annually compared to moss which only grows a few millimetres. Leafmould is not just an alternative to peat, it is in fact far superior and more versatile.
Mature leafmould both retains moisture and promotes aeration. After a year in storage it can be added to heavy soils to create a workable loam. This produces a feast for worms and soil micro-organisms which will flocculate clay and generate humus. After 18 months, it can be roughly chopped and used as a mulch or forked into established beds to improve soil structure, texture and tilth. It also darkens the topsoil which means it will warm up quicker and easier. It is ideal for rejuvenating tired, neglected or abused soils. At this age, it can also be prepared for use in potting compost mixtures by further chopping and riddling. Sieving through 1 cm mesh produces an ideal fibre for potting on established plants and seedlings or for rooting cuttings. Finer screening and older mould can even be used in seed mixes.
So when the first gales and frosts start to strip the trees bare, be prepared to harvest the best of the year's crop of leaves. You will find an abundant supply locally, if you get there before somebody else. It makes economic and common sense to collect and recycle this valuable, multi-purpose resource. The old practice of burning leaves seems bizarre and the municipal policy of dumping large volumes in landfill sites is almost criminal. Leaves oxygenate and filter the air we breathe. Leafmould is the gardener's gold-dust.
LEAFMOULD - HOW
AUTUMN - Collect leaves soon after they fall, when dry if possible. Sweep them into piles with a broom, fork or hay rake. Windy weather will often produce deep drifts ready for you to collect. Pack them into binbags or larger nets to carry to storage site. Larger loads can be carted by wheelbarrow or van.
A wide variety of leaves from different types of trees will result in a balanced end-product. Beech and oak leaves contain more calcium and makes the best mould. Sycamore is worst, only breaking down to a rough , woody fibre, but is still worth mixing with other types.
If you collect from local woodland, check with the landowner and only remove a fraction of the total. It may be necessary to remove twigs and branches.
Street leaves from busy roads will be contaminated by exhaust emissions, but all leaves pick up airborne pollution when growing. Correct processing will help to render these contaminants inert. Collect leaves from the pavement or roadside before the roads have been gritted with salt. Try to remove any plastic, glass or metal refuse as you collect and store the leaves.
WINTER - Stack loosely in a heap with blocked in sides so that the wind will not blow them away. Leave the top open to the elements so that the whole heap can become saturated with rainwater. After about two months, turn the heap to make sure it is fully moistened all the way through.
SUMMER - Pack the leaves down and cover with carpet and/or plastic to stop them drying out in hot weather.
AUTUMN -Chop vertically through the heap with a sharp spade into inch cubes. Transfer material to smaller containers to make space for the next year's leaves and store open to the elements for the second winter.
SPRING - Chop again then keep dry ready for riddling and rubbing to produce potting compost material.
7. QUICK METHOD / COMPOSTING OF LEAVES IN 3-6 MONTHS
By collecting sufficient leaves at one time, they can actually be composted, to create genuine humus-rich leafmould in less than six months.
If a sufficient critical mass of leaves [minimum 1000L = 1 cubic metre] can be gathered within a short period of time [one month], fungal spores will multiply as they consume bacteria on the surface of the leaves generating a heating reaction. The heat [40 degrees C +] effectively sterilises the material and can break down the cellulose structure of the leaves if it can be maintained for several weeks. Successful 'cooking' can produce material which is friable
[choppable] in the first spring after collection [12-16 weeks] and can be incorporated into the soil [dug under] with no ill effects.
The reaction will begin spontaneously from airborne spores on the leaves. Whereas, a compost process involves innumerable different species of micro-flora [bacterias, fungi, moulds etc.], the heat-generating reaction within the
leaf-heap is produced by a small number of specialist thermophilic actinomycetes [slime moulds]. The exothermic [heat-producing] reaction can be cultivated by ensuring there is sufficient moisture, aeration and insulation within
the heap , in the same way as a regular compost heap is managed. However, because it relies on just a few microspecies and has no progressive chain of redigestion of smaller by larger organisms, as is the case in compost, the hot phase of a leaf heap is less stable and more liable to interruption than a typical composting process. Unless the leaves are restacked regularly [every 3-5 days], to redistribute moisture throughout and restructure the heap to permit better aeration, the reaction can burn itself out due to lack of air or moisture.
The leaves need to be half-saturated [retained moisture content = 50% by weight : twice the weight of the dry material] for the initial inoculation to be able to colonise the whole heap. This moisture content should be maintained, replacing water lost to evaporation. Large numbers of leaves in a heap have colloidal physical dynamic qualities, their flat shape means that they settle into layers which insulate the center of the heap, retaining heat within the heap.
Within 5-7 days of stacking, evaporation from the hot center can cause the reaction to burn itself out in a process similar to firefang in compost. This laminating structure becomes so efficient after 7-10 days that it is impermeable to air and the reaction is suffocated and stops.
The aim of turning the heap should be to invert it [top-down + bottom-up] to distribute moisture throughout, and restructure it [inside out + outside in] to redistribute heat and aeration. Ideally, a stack should be turned regularly twice a week for one month. Initially, the leaves can be left uncovered until sufficient rainwater has wetted the whole mass. Hotspots at this stage can be spread to inoculate the rest of the heap with active digesting organisms. Once the reaction has been spread throughout the pile and sufficient moisture is present, the whole can be covered with plastic to retain and recycle condensed evaporation back into the heap, and with insulating materials such as carpet to allow heat to be generated and retained right out to the edges of the heap.
Well-tended heaps treated in this way are then warm enough to withstand the chilling effects of winter frosts and will remain warm for up to two months until all the bacterial nutrients on the leaves have been digested. Once the exothermic reaction has ceased the stack can be left open to the elements to resume a more gradual maturation process, or chopped through which reduces particle size and increases surface area, facilitating the incorporation of the leafmould into the soil.
The heating reaction can be enhanced and harnessed in several ways to improve the process and the end-product, remembering that it is relatively fragile and can be easily disrupted. Small doses of fine dolomitic limestone powder [2-5 Kg per 1000 Kg leaves] applied soon after collection, stimulate bacterial flushes and help to counteract the slight acidity of an average selection of leaves [especially if leathery, evergreen leaves are included]. Nitrogenous liquid feeds [such as urine or nettle tea] can be judiciously introduced to supplement water lost to evaporation when and where the reaction is strong. Care should be taken not to overwater and loose nutrients to runoff or leaching. Despite their cellulose structure, leaves will only have carbon available to bond onto introduced nitrogen after the exothermic reaction has begun to break down their molecular structure. Other soluble fertilisers could be introduced at this stage but only a small proportion of such materials will be bonded onto the structure of the leafmould, the rest remaining as free floating nutrients. Whilst lime is essential to the metabolism of the heating reaction, other additives are not necessary and should only be added where a higher fertility medium is required as an end-product.
8. SPECIAL METHODS OF PROCESSING LEAVES
1. INSTANT
Fresh leaves can be dug straight into very rough, weedy or heavy ground to help mechanically break up clods of clay and start to increase humus and soil micro-life. This is appropriate in the early stages of reclaiming overgrown land for cultivation over an extended period followed by later weed-control and green manuring. Inclusion of fresh leaves would also be a suitable method of initial improvement preceding the planting of any perennials, since they would be well incorporated into the soil by the time the plants are well-established.
2. PASTEURISATION
Compost freshly collected moist leaves by sprinkling with magnesium limestone. Turn every 3-7 days to redistribute and extend flush of heat for as long as possible. Dampen hot, dry spots in the center of the heap. Chop through the leaves vertically when the reaction ceases [after 2 months] with a sharpened spade every 10-15 cm.
3. ERICACEOUS FOR ACID-LOVING PLANTS [CALCIFUGES]
Include predominantly evergreen tree leaves [at least 50% by volume], such as conifers, rhododendron, holly etc. These have tougher structure and will take longer to break down [2-3 years], which can be speeded up by repeated chopping and turning.
ACCOUNT OF SOFI'S LEAF COLLECTION AND PROCESSING
This description of collecting leaves and producing leafmould was prepared for a PhD student researching a dissertation on the subject under the auspices of the HDRA [The Potential for Leaf Recycling in the U.K.: Rebecca
Baldock: August 1997: Coventry University]
We've been making leafmould for ten years for practical and opportunistic reasons; it was a free resource, abundantly available and underexploited. We have evolved methods of urban scavenging to facilitate as much local, organic food growing as possible, for myself and others. By accessing free resources such as leafmould, compost and other recycled resources, we can stretch our expenditure further, allowing the purchase of high grade imported
organic fertilisers such as seaweed meal. Leafmould is the most valuable and versatile free resource available as a food gardener.
For the past five years, our leaf harvest has followed roughly the same pattern. We borrow a van [Transit/Urvan-size] and spend 5-7 days from late October to early December [November]. We hope that dry, warm days, when the wind has recently piled up newly fallen leaves, coincides with when we have transport. We have perfected a method adapted to our scale of operations using large wooden hay rakes [18 inch] and inch-mesh nets [3 x 4 m recycled volleyball net]. We drive out to the genteel old leafy suburbs on the west side of Sheffield, where mature Victorian trees planted along wide, quiet avenues, yielding large crops of oak, beech, lime, chestnut, ash, maple and a wide variety of more exotic garden species. We try to choose roads with minimal traffic, grass verges and target the best possible quality and quantity available. Netloads are lifted into the van and packed down if dry.
Large volumes of leaves have some characteristics of a fluid when fresh and dry. They can be swept along and will flow over each other when pushed along. A metal rake scrapes too deep, scratching up tarmac and stones with the leaves and getting caught on minor obstacles like tree roots and cracks in the pavement.
In terms of the actual number of leaves collected, a dry load of 500 Kg is equal in volume to a 1 tonne wet load [unsaturated], and would require 3-4 times the volume of storage space when loosely stacked. It depends on just how wet the leaves are, but the energy and effort required to lift and shift them is much greater; twice as hard due to the weight of the adhering water. Warm, wet, muggy days are the most unpleasant conditions for collecting since you get wet on the inside as well as outside. We deliver about six vanloads per day and deliver these to a variety of allotment sites. They are stacked loosely in large bays [2-4 m square]. If the leaves are dry, they can be stacked up to 1.5m [6 ft] high, but the higher they are stacked the more they will need to be turned subsequently to ensure they are moist throughout.
The optimum condition of leaves for processing is approximately 25-50% water to weight of leaves, achieved when dry-fallen leaves have been exposed to showery rain for 48 hours or continuous rain for 24 hours. This can be achieved by progressively watering the heap when it is turned if no rainfall is available. In this state, a heap of sufficient critical mass [3-4 cubic metres] will heat up to 40-50 degrees C within a week irrespective of outside temperatures. However, without turning to redistribute moisture, the center of the heap will overheat and burn-out in the leaf equivalent of firefang, a white mycelium which reduces the leaves to a fungal mush when wetted. This is partly caused by the natural dynamic of the flat leaves settling into laminated layers, which act as increasingly efficient insulation for the center, If the heap can be inverted, turned inside-out and the moisture evenly redistributed, this exothermic bacterial-fungal reaction can be maintained for 2-4 weeks, if tended regularly, depending on weather [intensity and duration of frosts]. When able to harness this heating process, it is possible to create material which is friable [choppable within two months and can be dug into the soil in the first spring after collection.
Like compost heaps, leafheaps will benefit from additives if they are evenly distributed. Powdered limestone, specifically containing magnesium [dolomite or calcified seaweed], feed and favour flushes of bacterial growth which in turn invigorate the actinomycetes [slime-moulds] which together start to break-down the cellulose structure of the leaves. Lime should be added as a very fine powder to guarantee maximum distribution throughout the heap, but could also be sprayed on in water-suspension. If the heating reaction is strong and permeating the whole heap, diluted compost activator [piss] will further strengthen and prolong the heating. However, if the leaves are already saturated or too cool, no benefit is gained. The much longer maturation phase of the heap also provides opportunities to improve the quality of the finished mould. The basic aim should be to use minimal inputs to produce a homogenised base material for a full spectrum of uses. Hence any soluble agents for raising fertility should be added to the mature mould when it is included in mixes for specific uses. Insoluble mineral agents such as volcanic rock dust can be added at the preliminary stage to make use of the long storage time to break rockdusts down, resulting in a completed leafmould with additional plant nutrients and trace elements Both lime and rockdust should be added at a rate of 2-5 Kg per metric tonne.
We also collect beech and maple leaves from a nearby disused allotment site, which has reverted into young woodland. In this case it seems fitting to extract a small proportion of the annual leaf-fall to replenish working allotment soils nearby. Depending on whose land they're on and the status of the trees, extraction from woodland could be inadvisable. Excessive extraction could be ecologically disturbing and change the nature of an area of woodland, depriving plants and fungi of their annual mulch. But it could equally help to create more diverse habitats for plants demanding low fertility. It is also possible to create patches of deep litter mulch [eco-piles] made up of twigs, branches and rocks removed from the forest floor preferably before leaf-fall, providing useful new opportunities for animal shelter and enhancing the soil-formation process in these areas. As a rule, no more than 50% of the total shed of leaves should be removed in any given year.
Clearing leaves from public land is justified by the precedent set by the ancient Rights of Common, such as grazing and turbury [turf-cutting]. Leabury, the right to extract part of the leaf-harvest form common land, accompanied other privileges such as fattening pigs by allowing them to eat beech mast. Although catastrophically reduced by centuries of enclosure and privatisation of forest, these rights were never rescinded and are therefore presumably still applicable.
In total I would estimate that we make 5 tonnes of finished material annually. The majority of this is distributed over two acres of fruit and vegetable beds and 25-50% is retained as a base for a variety of potting mixtures. This supplies a large requirement for raising young vegetable seedlings and also provides enough medium for raising 1-2000 cuttings and herb plants in small pots annually. These intensive nursery applications are the most effective use for fully mature leafmould. I have never experienced 'damping off' or retarded growth in beech mould, both of which are sometimes mentioned as worries in connection with leafmould.
In my experience, leafmould is both superior to and more versatile than either peat or coir.
The end-product contains a wide spectrum of trace elements, according to the diversity of tree species included.
The decomposed leafmould has a very high humus-forming potential when digested by soil micro- and macro - organisms, with consequent benefits for soil structure and the mobility of nutrients throughout. Humus is formed when the minerals in the clay are bonded onto the proteins from the leaves. On heavy clay soils there is no better agent for radically improving structure, tilth and water-holding capacity.
10. MAKE YOUR OWN WORM COMPOST .
Vermicomposting is especially relevant in an urban context where space is at a premium and sources of fertility are often in short supply. The following text has been issued with accompanying illustrations to assist inner-city flat dwellers to recycle their organic waste and produce top-quality compost.
Worm bins are safe and convenient. The solution for people with not enough materials to make effective compost heaps, as worm bins perform best when matter is added a little at a time, and for those with little space or no garden.
Worm compost is a distinct product characterised by a high humus content which is superior to any other growing medium.
SETTING UP: Any uncontaminated, clean plastic container will suffice. For the average household a container of at least five gallons capacity is required. For example, a plastic fermenting bin or dustbin. A lid is needed, but should be well perforated with small holes [3mm diameter] to provide good ventilation, but prevent the worms from straying out.
Drainage is essential, either a tap at the side, or holes in the bottom with the bin stood on top of a sturdy bowl or equivalent. Alternatively, it is possible to use a wooden box. If the box has a large surface area, this enables the worms to feed most efficiently.
WORM SPECIES: Eisenia foetida, also known as red, tiger, brandling, compost or manure worms. Found in leaf litter and manure heaps. They are also available commercially (including a related and equally effective species, Eisenia andrei) or from anglers shops. You need at least a hundred worms to start with, but about half a pound weight is recommended as a minimum colony to digest the organic waste from an average household .
BEDDING: Good bedding is required for settling in the worms to their new home and as a site to return to should conditions in the bin become temporarily uncomfortable (overloaded with raw material). Suitable materials make both air and moisture available to the worms and should retain its structure for as long as possible. Well rotted garden compost, manure or leafmould are the most natural bedding materials, which will also help to introduce more worms and their eggs and young to the process. Straw, hay or well shredded and moistened plain corrugated cardboard or thick brown paper bags are adequate. Smaller and thinner materials such as sawdust or newspaper will tend to compress into a solid mass, impenetrable to the worms.
OPERATING TEMPERATURE: The worms will remain active between 35o'F and 84oF [2-30oC] but they work most effectively between 55oF and 77oF [12-25oC]. Worms may try to leave the container if it is too hot or cold for them. Consider these limitations when siting the bin. Good examples are a cellar-head, garage, shed or cool kitchen. Carpet, bubble wrap or equivalent cover for the top and sides can be employed for winter protection.
TO START THE BIN: Layer in 4 - 6 inches [10-15 cm] of bedding, mixed in with two handfuls of clean soil, which provides grit for the worms' gullets to grind up organic material. Bedding should be well moistened but not saturated.
Add the worms and allow them to settle in for a week. You can then gradually add the materials you have collected for composting.
WHAT CAN GO IN THE BIN: Fruit and vegetable peelings. Large lumps and tough stumps are best diced into 1 inch [2 cm] pieces before inclusion. Food scraps such as bread, cooked rice, pasta and porridge. Tea leaves and coffee grounds. Garden weeds. Egg shells.
Dairy produce such as cheese, only in small quantities.
MAINTENANCE: Dust lightly every 4 - 8 inches [10-20 cm] with either dolomitic lime or calcified seaweed to keep the contents 'sweet' (pH balanced) and provide necessary calcium for the worms' reproduction. Take care not to overload the system, or the bin contents will start to putrefy. This will result in the worms retreating to their bedding or, if conditions are very bad, trying to escape out of the top. Add materials a little at a time, up to 3 inches deep as a rule, then leave the worms to work their way through most of this material before adding more.
READY? : After about six months of normal operation, much of the bin will consist of worm castings, or vermicompost., which can now be extracted. Remove the top several inches of raw or not fully digested material and keep aside. This should contain a substantial quantity of the bin's most active worms. Turn out the rest of the bin's contents. Try to recover as many worms as possible from this compost to enable a fast return to normal operation of the bin, including any of the small, oval, yellow eggs. This extracted compost may need a little drying out before it can be used easily, especially if you intend to sift/riddle the material. Restart the bin by adding fresh bedding and soil, followed by the worms, then finally adding the raw and undigested matter with a little dusting of lime.
USES OF WORM COMPOST: Use judiciously in seed and potting composts. It is a concentrated product and so even a little can greatly improve the quality of potting mixes and the health of seedlings, in particular. Sprinkle a little into seed drills before sowing, especially during dry conditions, or for slowly germinating seeds. Rake into seed beds to improve texture and provide a balanced set of nutrients. Worm bins are particularly popular in the USA and Switzerland, where the compost is used for houseplants and for all sorts of container growing. The restricted and stressful conditions imposed on a containerised plant are well ameliorated by the use of worm compost. The 'leachate' caught in the bottom or from a tap at the side can be used at a dilution of approximately 1:10 parts water as a general purpose liquid feed.
MAKE-UP OF WORM COMPOST: Worm compost contains large amounts of humus. Humus is a complex material formed during the breaking down of organic matter. It provides the binding sites for plant nutrients such as calcium, iron, sulphur, potassium and phosphorus. These nutrients are stored in humic acid in a form readily available to plants, as and when the plant requires. Also, humus improves soil structure, enhancing aeration and moisture retention, and can help buffer excessive acidity or alkalinity in a soil or growing medium. Additionally, humus exerts beneficial control over plant pathogens, nematodes, harmful fungi and bacteria.
PROBLEMS? If the bin does not seem to be working, or worms are trying to escape or even dying, it could be...
1. Too hot/too cold. Re-site the bin accordingly.
2. Overloaded. This causes putrefaction, bad smells and the presence of flies (though usually only harmless fruit flies). Aerate the top of the contents with a handfork, sprinkle in some lime and add fresh bedding.
3. Unbalanced materials. If the bin smells but is not overloaded, it may be that it contains too much salty or acidic matter. Corrective strategy is same as for an overloaded system. Add a wider range of materials in future.
BUGS: Most creepy crawlies seen in the bin are integral to the composting process and so are friends, not foes. You may spot tiny white 'pot' worms; these perform the same as brandlings, but far less efficiently, and are an indicator that conditions are waterlogged and probably somewhat acidic.
FUNGI: Fungi and moulds are also an integral part of the normal composting process. If large moulds are developing on the surface just turn them in slightly with a hand fork. If you have an allergy to fungi and mould spores, you may not be able to cope with a worm bin situated in the house, but will most probably be alright with one situated outside.