Organic matter that can be composted or added to the soil, is anything once was alive but also includes the microbes associated with it. Organic matter embraces all the following,
1. Garden plant litter probably the most diverse source of organic matter in gardens and allotments.
Garden waste will include composted crop waste such as bean and pea stalks, beetroot, parsnips, Hamburg parsley, salsify, scorzonera, carrots, swede, turnip and celeriac tops, potato haulms, tomato, sweet corn, pumpkin, cabbage, Brussel sprouts, purple sprouting broccoli, maize cobs and kale plants. Crop waste is what is left after removal of harvested parts and most crops produce voluminous amounts of residues which are sources of plant nutrients especially after composting. Significant amounts of nutrient can be added to the soil from crop waste. Where crop residues are left to be dug in, the nutrient content of these residues is recycled and made available for following crops. When crop residues are removed and burnt their nutrients will be lost to the allotment irredeemably. With some crops such as beetroot, parsnips, cabbage, cauliflower, beans and peas large amounts of stem and leaves are left on the grow beds. They represent a large and valuable reservoir of nutrients and these can be composted, and the nutrients returned to the soil. Compost can include cut flower plants like sweet peas (which are poisonous), dahlias and chrysanthemums. Even poisonous rhubarb leaves can be composted because they are certainly not poisonous to microbes, which rot them down very quickly. The prunings of soft fruit and top fruit cut into 5cm pieces will rot down relatively quickly in a regularly turned compost heap. Unwanted wild flowers, more commonly called weeds, are valuable additions to the compost heap but need soil removed from their roots so that it does not squash the compost down. I compost all weeds regardless of their reputation. However, I think that I would have to dry Japanese knotweed for a few months before adding this to the compost, but I would give it a go if I had it on the allotment. Only put mare’s tail, bind weed and couch grass on the compost heap after drying them well, otherwise put them into the worm bin. Weeds are nutrients.
With the way that I make compost, sieving it carefully before putting it on top soil, I think that anything that regenerated would quickly be seen and removed. Anyway, it would be a very resilient weed that could recover from being turned every two days for over two months. All these sources of organic matter will be decomposed by the compost microbe community.
Diseased material can be added to the compost heap if high temperatures can be achieved, however they may be better buried deep in the subsoil. Here they will not be able to do any mischief while still adding organic material to the allotment soil. Aphids such as the lupin aphid, black spot, brown rot on fruit, canker, grey mould, leaf miners, mites, mildews, potato blight, sawfly larvae can be put onto the compost heap if the temperature can be kept at 70oC or above for several days.
2. Kitchen waste including all vegetable and fruit peelings, kitchen absorbent paper used to mop up normal spills, coffee grounds and tea dregs, paper coffee filters, spent tea bags, egg shells, bones and corks. Egg shells are calcium phosphate and a little calcium carbonate; the same compounds that are in bones, rock phosphate and limestone all of which contain valuable plant nutrients. The fact that there are not great piles of undecomposed egg shell from the hundreds of thousands of years of production does indicate that they readily weather down into smaller pieces and are easily incorporated into the soil where microbes can work on them to release valuable elements. The organic matter in eggs comes from the small amount of protein inside the shells.
3. Water from the cooking of vegetables. This has an amazing effect on house plants.
4. You can use cooked food residues too, such as bread, cheese, cooking oil, lard; mayonnaise; meat, milk, pea nut butter, salad cream, salad dressing; sour cream, but it probably be best to put this material in worm bins that can be sealed or mix them thoroughly with woody chippings before composting. I have used sour milk in worm bins together with rancid yoghurt with no noticeable effect except to increase the population of worms. They say that cooked food attracts wildlife like rats, but no one has told the rats on my allotment because they infest my compost cooked food or not. I think they just like the warmth. Denatured proteins and slightly decomposed cooked food is broken up in compost very quickly as are dead animals. While it may not be acceptable for some people, I feel that road kills are much better respected if buried on the allotment. I have no problem with using dead rats and mice on the compost heap. They decompose in a couple of days.
5. Attracting birds by providing perches, bird boxes and feeding stations means that their droppings will fall on the allotment soil. Badgers, foxes, rats, mice, voles, toads, frogs and newts all visit, some finding a niche in which to live, and will excrete on the allotment and add nutrients to the soil. Newts, toads and frogs will live in and around ponds and will also act as predators and help to control pests. If animals are regular visitors to the allotment, there will be a constant, if small, addition of extra imported nutrients that will build up slowly and improve the fertility of the topsoil. Plants don’t need a lot of nutrient to survive. Habitat creation in terms of hedges can involve just traditional plants like hawthorn or edible fruit hedges such as Elaeagnus x ebbingei “Gilt Edge”. However, hawthorn has the largest number of associated organisms apart from oak trees.
7. Attracting and maintaining a high population of invertebrate organisms will bring frass and uric acid onto the allotment. All animals will help mineralisation by cell death turnover, protein breakdown and excretion through the kidneys or other excretory structures as urine, uric acid or urea. While it can be said that uric acid and urine are not organic compounds, they are central compounds in the cycling of nutrients on the allotment. It may seem that these will be only very small additions to the fertility of the allotment soil but if there is a good population of various animal wildlife then the constant additions, from food gleaned from outside the allotment will be imported and slowly build up. Live invertebrates in the soil have similar benefits to that of dead organic matter with the additional advantages that invertebrates turn the soil over, excrete uric acid or urea and help in mineralisation of dead organic matter. Surfaces and guts of invertebrates are places where organic matter, live or dead, can be attached and moved around, mixing them with the mineral parts of the soil. All organisms excrete, shed cells and die adding to overall soil organic matter whether in the soil or compost.
Soil organisms contribute to weathering by production of carbon dioxide through respiration which, when dissolved in the ground water, will produce carboxylic acid. This and other organic acids produced by microbes will contribute to the breakdown of rocks, stones, pebbles and small mineral particles in the soil. Many organisms produce secretions of viscous material. They often consist of a polysaccharide and protein mixture and are probably associated with attachment of organisms to surfaces. Soil fauna, particularly molluscs and earthworms affect the soil through the secretion of mucus which has a cementing effect on soil particles contributing to the stability and structure of the soil and making it less vulnerable to erosion. Animal mucus secretions, especially those of earthworms, and their bodies when they die, considerably influence the concentration of nutrients in the soil particularly of phosphorus, potassium and nitrogen. You can see on paving slabs where algae, fungi, litchens and bacteria make a sticky concoction of polysaccharide slimy goo designed primarily to get you to slip over on it. Together with seeds and spores of plants, live elements are added to the compost in or on the vegetation added. However, weed seeds and spores are already a major part of the soil organic matter.
8. Farm waste including animal dung, straw, hay, broken eggs and feathers. If you can get hair, hoof and horn clippings all the better because they contain proteins like keratin - and proteins contain the important nutrient nitrogen. Horse stable manure mixed with combings, trimmings and clippings can be put onto the compost heap. The bedding of pets like rabbits, guinea pigs and gerbils can also be composted together with the fur of cats and dogs. I would avoid using the droppings of carnivores on the allotment, however they can be buried deeply in the soil.
9. Cattle manure can be dairy or beef, cattle urine, chicken manure, horse or stable manure, human manure, human urine, pigeon manure, poudrette (night soil) from waterless toilets, sheep manure, sheep urine, pig manure and pig urine. Farmyard manure is a mixture of manures. Farm yard manures are a bulky organic manure resulting from naturally decomposed mixture of dung and urine of farm animals along with their litter. In addition to nitrogen, phosphorus and potassium it can contain iron, magnesium, boron, molybdenum, cobalt, aluminium and chromium in trace amounts. The nutrient concentration of fermented, moist farm yard manure depends on what the animals were fed on and can vary greatly. Manures are best mixed with bedding because it absorbs urine. Urease is a ubiquitous enzyme that breaks down urine and is produced by many soil microbes probably because animals are peeing all over the shop. Urease breaks down urine breaks down urine into ammonia and carbon dioxide. Manures are usually very biologically active because they have passed through the animal’s gut with its bacterial flora. The bacteria in the guts of herbivorous animals produce enzymes that decompose cellulose. The bacteria obviously produce more nutrients than they use themselves giving animal access to cellulose nutrient breakdown products. A proportion of these bacteria are added to the allotment soil when manure is spread on or dug into the top soil. They continue to function in the manure and help to increase the diversity of microbes in allotment soils.
10. Poudrette or human excreta is rich in nutrients, and its value as manure was much more appreciated before the adoption of the flush toilet and sewers.
11. Leaves from forest trees and leaf mould even from walnuts. Walnut leaves will contain juglone which will inhibit the growth of plant seedlings. It is noticeable that there are no enormous piles of walnut leaves undecomposed under these trees. This is because juglone is just another organic compound as far as microbes are concerned, which they will eagerly devour. As we don’t have great mounds of undecomposed walnut leaves under the trees I would suppose they are decomposed quite readily together with the juglone that prevents seed germination. Lots of poisonous plants can be put onto the compost heap like rhubarb and sweet pea plants. Fungi and bacteria will break them down into harmless materials.
12. Conifer needles are more of a challenge for microbes to digest because of the phenols in them. However, the specialist decomposers will devour these given sufficient water. Pine tree needles, holly leaves and shreddings will rot down relatively quickly in a mixed compost heap.
Tree leaves can be composted on their own to make leaf mould, but they need to be kept wet for the microbes to decompose them. In Victorian times gardeners could not buy compost from the garden centre so they had to make their own. They used leaf mould to make very good seed and potting compost. This is why they composted leaves separately from other organic matter. There is no other reason for composting forest tree leaves separately and tree leaves can be put on the general compost heap. They will rot down wherever they are put. Leaf mould and shreddings add organic matter to the soil but contribute only moderate amounts of nutrients. Good potting compost can be made from leaf mould because it is more reliable, predictable and lower in nutrients than compost. Leaf mould has a low bulk density with an open, water retentive texture and contains less weed seeds than compost. However, it will not sustain seedling growth for very long and the plants will have to be transplanted relatively quickly into more substantial soil.
Newly shed leaves will lack in nitrogen but will still decompose relatively quickly if kept moist.
13. Hedges used as windbreaks can be harvested for the hedge trimmings and litter including leaves, flowers, fruit and die back twigs that fall from the hedge throughout the year. They act as leaf traps in the autumn and this can be enhanced with chicken wire. The litter both from the hedge and that caught in the windbreak can be collected and composted. You do not have to have a separate compost heap for tree leaves. These may well be broken down by fungi but there are lots of fungi in compost heaps and they are not going to turn their noses up at the prospect of having to consume leaves.
14. Charcoal, although some would say that this is mostly inorganic carbon. I like to marinade it in comfrey liquid and urine for about three months so that it is thoroughly infused with nutrients. It can then be crushed and applied to the soil. I doubt very that charcoal on its own increases the fertility of the soil. Charcoal is the residue of incomplete combustion of organic matter. It is a chemically and biologically stable form of carbon and can persist in the soil for long periods of time. Archaeologists use charcoal for carbon dating. It is not inert, and it can be changed to carbon dioxide by UV light and oxidation. The effect of UV light on organic compounds can easily be seen when we spend too much time in strong sunlight and get sunburnt.
Only a very small part of the solar radiation reaches the soil because most is absorbed by the ozone layer. The small amount that does reach the surface can power reactions and contribute to the breakdown of organic matter. Organic woody material rich in lignin shows much more sensitivity to UV than “green”.
There is evidence that suggests that charcoal and compost mixes improve crop yields significantly. Charcoal supports its own microbial community which is small but more active than that on other organic matter. This microbial community will add diversity to the allotment and may provide the soil with vital services that are absent otherwise. Charcoal can adsorb plant growth inhibiting compounds and create a habitat for microbes that will decompose them.
15. Wood chips and woody shreddings are very valuable compost and mulch materials particularly if they have been weathered. When used as a mulch they make the allotment soil surface like the forest floor and introduce many beneficial organisms. A wide diversity of fungi begins to grow in the shreddings and these saprophytic fungi will compete with other fungi making sure that none increases their populations excessively and becoming a pest in the allotment soil. I want these fungi to compete with club root and onion white rot fungi and using the woody shreddings as a mulch on the brassica and onion bed certainly has its advantages and pest resistance may be one of them.
I am experimenting with woody shreddings as an addition to the compost bins. For years I have been telling people not to add these woody shreddings to the top soil because nitrogen is depleted by microorganisms that decompose them. I'm not so sure now. Immobilisation of nutrients, particularly nitrogen, is the reduction in plant available nitrate or ammonium salts dissolved in the ground water because microbes use this nitrogen as they decompose organic matter with high carbon content.
So, I have filled one of the dalek bins with shreddings and will be turning it every two or three days with the other bins. I want to see whether this material will decompose as quickly as some of the other compost ingredients.
Particle size is important, and the surface area exposed to microbial attack can be increased by having smaller chopped up fragments. The smaller the particle the faster the decomposition. Water insoluble resins in softwoods resist water, making their wood particles more resistant to microbe decomposition until specialist organisms break them down. Bark and suberin are also water repelling and need to be broken down by oxygen, UV light or weathering before specialist microbes can begin to decompose them. Solar radiation that reaches the soil and can degrade plastic ground covers that are not UV stabilised. Even stabilised plastics can be seen to degrade noticeably over several years.
16. Organic wastes from industrial processors such as hops, fleece, wool, hoof and horn, blood fish and bone, hair and fish meal. Addition of hoof and horn and bone meal to compost will help to mix them with other organic matter, effectively diluting them so that their effects can be spread over a large surface of soil and preventing concentrations in particular areas.
If concentrated fertiliser is applied to the soil it may lead to damaging concentrations of salts and damage roots through osmosis removing water from delicate root hairs. What gardeners call root burn and is much more likely with the addition of concentrated nutrient salts than with organic matter additions. Nutrients can be added in the form of sea weed meal; blood fish and bone and hoof and horn meal.
Bone meal is rich in phosphates, while hoof and horn is rich in nitrogen. Hoof and horn is a slow acting nitrogen fertiliser worth adding to flower garden. Bone meal is made from animal bones. Raw bone meal is ground bones without anything removed. It contains nitrogen, phosphorus and some micronutrients. Steamed bone meal is treated crushed bones, with some gelatine removed, ground into a powder.
17. Shredded paper waste and, even better, organic shredded paper waste. I would compost this because it will tend to remove nitrogen from the soil by immobilisation if added in too large amounts. Screwed up newspaper.
18. I love card and cellophane. They both rot down so quickly especially the corrugated card. Lots of this brown card has been recycled several times leaving fibres exposed to microbe decomposing enzymes and acids. Card is useful to use as a mulching material under woody shreddings but be prepared for it to rot away quickly. I tear up card fliers and packaging to put onto the compost heap. When turning the compost every two days card disappears in a week. Of all the additions you can make to a compost heap one of the best is brown cardboard. It rots down remarkably quickly even though it is made primarily from cellulose and hemicellulose fibres. The rapid decomposition is mostly due to the open pulpy structure that acts like a sponge to water and gives a very large surface habitat for bacteria to live on. However, where sticky labels and tape have been left on the cardboard it is protected and takes much longer to decompose. The polysaccharides
19. Clothes made from wool, animal skins, silk, cotton, linen, nettle and hemp. Any clothes made entirely from plant or animal fibres are fine to put onto the compost heap.
I am composting some leather gloves; leather boots; a cotton shirt; woollen socks and woollen trousers. I do not expect them to decompose quickly but they will decompose. Leather shoes, belts, straps, hand bags, saddles and horse tackle will all eventually rot away and form a rich compost. Using these materials might cause some soul searching for vegans. However, they decompose, and I would rather they did so on my allotment giving them some respect as a nutrient source and opportunity for them to be recycled than for them to be buried in a land fill site.
Carpets made from jute, cotton and wool can be composted but make sure they are very old ones or have been weathered well to wash out any industrial chemicals. Pesticide industrial chemicals are put onto carpets to stop them being eaten by fungi, moths and mites, all of which live in compost, helping to break it down, and will be vulnerable to these chemicals.
20. Scum, sludge, moss and leaves from gutters and drains preferably composted.
21. Shavings, sawdust, husks, chaff and stubble are best composted because they will immobilise nitrogen in the soil.
22. Urine added to comfrey tea or compost.
23. Guano covers fertilisers derived from small animals like bats, birds and fish. Using guano from sea birds will help to recycle nutrients that have been lost to the sea.
24. Old potting compost, seed compost, grow bag compost, hanging basket compost.
25. Stems, branches and brushwood from shrubs and trees. These can be shredded and composted or used in Hügelkultur beds.
26. Sea weeds are best composted until excess sea salt has been weathered out. Shells from the beach, which are mainly calcium carbonate but do contain some protein. Plant nutrients are constantly being washed down to the sea through ground water, rivers and streams. These nutrients will be lost unless there is some way they can be recycled. Using sea weed and sea weed extract liquid fertilisers either directly on the soil or on the compost heap help us to recycle these lost nutrients. Ascophyllum nodosun (kelp); Laminaria digitate (Kelp) and Fucus serratus (wrack) are just a few of the algae that can be used on the compost heap to give compost a diversity of sources. Their addition to the compost heap is more as a plant growth stimulator than a nutrient supplier.
27. Composted bark, cocoa shells, peat and coir.
28. Mushroom compost is mainly very well-rotted horse manure, hay and straw and can be added straight to the vegetable garden soil.
29. Worm compost – although it’s not just worms – and worm tea. Vermicompost contains earthworm cocoons, excreta, beneficial microorganisms, plant nutrients, enzymes, hormones etc all of which are good for conditioning the soil. It contains the nutrients nitrogen, phosphorus, potassium and the trace elements iron, zinc, manganese and copper. Vermicompost is the stuff left in the worm bin after the liquid has been drained off for several months. I leave mine in the bin for about a year before putting it on the allotment or compost heap.
30. Lawn and weed turfs can be stacked for six to twelve months, upside down to kill off the grass, and added straight onto the vegetable garden. Turf will also make good potting soil if it has been stacked for long enough. It will decompose into a crumbly loam which can be used as a mulch or top dressing in pots and containers. Turf has a lot of soil in it and this will increase the bulk density of compost, so it is best stacked on its own.
31. Lawn mowings which can be added straight onto a well-made compost that is being regularly turned. They rot down very quickly helping other ingredients of the compost to decompose rapidly too. This is probably not because they have more nitrogen in them than any other leaves but because they have been shredded and have a large surface area exposed to bacteria attack.
32. Herb teas such as comfrey, nettle and sweet cicely or mixtures of them. Comfrey contains relatively high levels of the basic NPK nutrients drawn up from deep in the soil by its extensive root system. The NPK mix makes it an ideal general fertiliser for most vegetables.
33. Green manures such as field beans, alfalfa, clover, fenugreek, lupin, field peas and vetch, which will add nitrogen as well as organic matter. It can be dug in or covered with card and shredded woody material and hoed in when it dies down. Green manures have less nutrients than some other manures but high soil fertility improving resource. Composting can improve their value as a nutrient resource. Composting will improve their value as a nutrient resource.
34. Perennial legumes like lupins, laburnum, wisteria, broom, gorse, together with Frankia infected plants like Elaeagnus x ebbingei, which can be used as chop and drop or cut up and put on the compost heap. The exudates and secretions of perennial legumes together with their composted seeds, stems, leaves and branches will all add organic matter and nitrogen to the soil. Crop residues of legumes, such as beans and peas are richer in nutrients and have a relatively high level of nitrogen which helps decomposition and mineralisation by microbes. I like to dig the haulms of peas and beans directly into the soil after they have gone over.
35. Cover crops such as mustard, grazing rye, wheat, buckwheat, forage radish, turnip, and caliente mustard which will immobilise nutrients over winter and prevent them from being eroded or leached away before they are dug into the soil in the spring.
36. Water butt, pond, stream, lake, canal and river silt are all rich in organic matter, but I would still compost them for a while. It is best to remove a large proportion of the aquatic plants from ponds regularly because they tend to take over if left. Removing duck and blanket weed reduces the amount of nutrient in the pond water.
37. Water plants harvested from rivers and ponds will short circuit the loss of nutrients if these are composted.
38. Old bee hive wax combs and dead larvae can be composted.
39. Vacuum cleaner fluff, if you have a woollen carpet, and fluff out of washing machines. Washing machine lint and clothes drier lint will probably contain manmade fibres which will not rot down so may be worth avoiding. Vacuum cleaner waste can contain a lot of hair particularly if you have a pet. Hair from brushes and combs, whether pet or human can be composted. Hair is mainly keratin which is a protein and relatively high in nitrogen. Dust is primarily very small soil particles and not flecks of skin. However, if it were skin, this too is high in protein and thus nitrogen. Also, the flecks of soil or dust particles still contain nutrients and would be a valuable addition to compost heaps. Household sweepings from hard kitchen floors are always worth adding to the compost heap as well.
40. As any allotmenteer with a forest tree near their allotment will tell you, there is a constant rain of leaves, dead twigs from dieback, flower buds, flowers and fruit debris that fall onto the allotment throughout the year and all this can be swept up and composted.
41. Root detritus is often as large as above ground additions of plant litter. Fine roots will contribute more soluble nitrogen than leaves to the soil. By contrast leaf litter contributes considerably more carbon in the form of cellulose, soluble phenolics and lipids. Fine root turnover contributes long lasting organic matter and great quantities of recalcitrant compounds are returned to the soil through fine root turnover.
Grasses are particularly good contributes to this system. Grasses increase porosity, water retention, permeability and crumb structure. Therefore, rye grass is an effective cover crop.
42. Processed wood is a little more problematic because it may have been chemically treated or painted. Very weathered and rotting processed wood is probably worth putting through the compost heap before adding to the top soil. I do use processed wood in hügelkultur trenches and bury the wood in the subsoil but whether this is a good practice I am not sure. I have had no noticeable effects on the vegetables that have subsequently been grown on the hügelkultur – in fact they have been quite good – but process wood should be used with caution if added to the soil or compost heap. Only compost processed wood after being exposed to the elements for several years and it shows signs of decay. If fungi are living in it, the preserving chemicals have been weathered and broken down and rendered harmless.
Wood rots and more rapidly than you expect.Use what is available.
A rich compost will be made if just a small proportion of this organic matter is used. The diversity of ingredients will be reflected in a varied microbe community and pest and disease suppression due to competition for nutrients and space.