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How to Create Humus & a Thriving, Living Soil

  1. How to Increase Soil Carbon
  2. How to Make Great Compost
  3. Growing Compost Crops
  4. How to Make Leaf Mould
  5. Amazing Earthworms
  6. How to Increase Earthworms in Your Soil
  7. How to Worm Compost
  8. How to Encourage Mycorrhizae Fungi
  9. How to Make Bokashi Compost
  10. How to Grow & Use Comfrey
  11. How to Use Green Manures
  12. How to Make Liquid Manures
  13. How to Create Terra Preta
  14. How to Use Mulch


Agricultural soils worldwide are loosing massive amounts of organic matter in its finest form – humus. As a result conventional agriculture and horticulture are burning off humus in the form it was taken in by plants in the first place, namely Carbon dioxide, contributing to the increase in atmospheric CO2.

In the U.S. alone, since 1940 there has been a 75% loss in soil humus in agricultural soils – with a subsequent loss of soil life, soil structure and a reduction in water retention. This destruction is being seen worldwide, due to a combination of a lack of regular humus creation, plus the over use of inorganic fertilizers, such as nitrates which burns up the humus and super phosphate which kills mycorrhizae fungi.

Our role as sustainable gardeners, horticulturists and farmers, must be to stop using destructive chemicals and at the same time build up soil carbon and humus levels. So, how can this be achieved?

  1. For gardeners, professional horticulturists and lowland farmers, regular compost making out of both onsite and imported organic waste on both small and large scales, should become a natural part of the activities of these enterprises.
  2. Making worm compost, especially for composting food waste.
  3. Regular growing of green manures in gardens, horticultural and arable farms.
  4. Creating ‘Terra Preta’ through the addition of ground charcoal to soil.
  5. Reducing digging and ploughing and the use of ‘no-dig’ and ‘minimum tillage’ techniques to reduce the oxidation of soil organic matter, and to minimize interference with beneficial soil life.
  6. Actively encouraging earthworms and mycorrhizae fungi through the reduction of cultivation and the addition of beneficial microorganisms and mycorrhizae spores to the soil to help the composting of organic matter into humus and to increase soil carbon levels.  

So let’s be practical. The following section describes the approaches and practical applications used by any organic farmer, organic horticulturist or a gardener who just wants to be as organic and sustainable as possible.

So how can we apply our knowledge of this co-operative process between plants and the micro-organic life in soil? We need to encourage an abundant population of beneficial micro-organisms and at the same time increase the soils capacity to hold onto nutrients, called the “exchange capacity”. As already described, it is the organic humus particles (colloids) along with clay particles that through static electrical charge hold onto plant nutrients. Ordinary organic matter from the compost pile, or the remains of last year’s crops, doesn’t have much exchange capacity until it has broken down into humus. The formation of humus requires the action of soil micro-organisms, earthworms, fungi, and insects. When none of them can do anything with it as food anymore, it ends up as a very small but very complex Carbon and Nitrogen structure (a colloid) that can hold and release many times its weight in water and plant nutrients.

The higher the humus levels in the soil, the greater the exchange capacity – 5 per cent humus in a soil is a minimum, with 10 per cent being a good figure to aim for. Humus is constantly being broken down in a healthy soil, so it is essential that we regularly replace the organic matter in the soil and increase it to a healthy level. By doing so we will both increase the nutrient holding power of our soils and at the same time foster a huge population of micro-organisms who will feed our plants.

The amount of clay in any given soil is determined by geology, but organic humus can easily be increased by us. We need to build up well broken down organic matter that has become fine humus as well as applying regular supplies of fresh unrotted plant material. Fresh plant material encourages a huge army of micro-organisms, worms and other essential soil life, while the fine humus colloids hold onto nutrients until the plants require them. In nature, top soil is built up slowly, but we can greatly speed up this process, taking advantage of photosynthasis and its capture of carbon from carbon dioxide to make cellulous. For fine humus, make compost – for fresh organic material, grow green manures.

PhotosynthesisEnergy, Cellulose & Proteins:

So far we have concentrated on soil nutrients and the ways plants access and utilise them, but the largest proportion of any plant comes not from the soil, but from above. Through the miracle of photosynthesis, plants breathe in Carbon Dioxide and with the energy of light from the sun, plus water, produce the bodies of their cells (cellulose C6H10O5), their glucose (C6H12O6) and with the addition of Nitrogen make their proteins from the atmosphere, which is 78 per cent Nitrogen, which is sequestered by Nitrogen fixing soil bacteria, Rhizobia in the root nodules of legumes, soil protozoa and some soil algi.

This is why one can sequester more and more carbon to add to the soil, because every year plants convert CO2 into the cells, lignins and wood that makes up their bodies. This can then be composted down, or in the case of wood, can be turned into charcoal to be added to the soil. There is therefore a net gain, especially in the early years of building up humus levels in the soil. However humus is continuously being broken down by micro-organisms as Sir Albert Howard explained:

Humus is not in a static, but rather in a dynamic, condition, since it is constantly formed from plant and animal residues and is continuously decomposed further by micro-organisms.  Humus serves as a source of energy for the development of various groups of micro-organisms, and during decomposition gives off a continuous stream of carbon dioxide and ammonia.

As the percentage of soil humus colloids increases so does the microbial and mycorrhizae fungi activity and the biological and chemical processes they initiate. As a result the breakdown in humus colloids increases and the need for regular replenishment is ongoing. However to replace the humus consumed every season, after it has reached healthy levels of between 5 and 10 per cent, requires less carbon rich material than was required to build up the humus content in the first place. None the less regular quantities of compost and green manures need to be applied to the soil on an ongoing basis, especially if intensive horticulture is carried out. To do this you need have consistent compost production, regular winter green manures, and if you have the space, you should grow carbon crops especially for the purpose of trying to be self sufficient in carbon rich plant material.

The point is this, carbon rich material is free from the air and is there to be converted into humus to enrich and enliven soil life, to enhance soil structure and to provide Nitrogen for plants from its 10-1 Carbon/Nitrogen ratio.


Many make compost, but few know how to make good compost. To make good quality compost which will enrich the soil, we need to understand the theory and the practical application. The theory is the science bit and the practical bit is an applied craft which improves over time.

Theory and Practice:

The organic goal is to feed the soil and more importantly the life within it, not the plant. This is achieved by providing as much high quality humus as possible to encourage a vibrant living soil.

  • To make humus, one requires lots of high cellulose plant material such as straw, crop wastes, hedge trimmings etc…
  • It is best to save up this material until you have enough to build a 1 cubic heap, or at least 1/2 cubic metre.

    Material Collection

    Material Collection

  • To break down this high Carbon-cellulose material, requires high Nitrogen animal manure (horse, cow, sheep, goat, or chicken), urine, soft green plant material such as green weeds and grass mowings etc, dried blood and bone, dried fish meal – or any combination of any of these. This high Nitrogen material willhelp to create the protein to build the bacteria’s bodies that  break down the cellulose in the coarser material.

    Horse poo

  • In this approach, high nitrogen manure and urine is no longer seen as a plant food in its own right, but as a precious activator to enable the creation of a much larger amount of an even more valuable end product – compost.
  • All organic matter brakes down to a settled state with an eventual carbon nitrogen ratio of 10 parts Carbon to 1 part Nitrogen.

    Dried blood powder

  • High cellulous materials like straw, dead leaves etc are high in carbon.
  • Animal manures, dried blood, urine, grass mowings, green succulent weeds, lucerne meal, etc are high in Nitrogen (proteins and protein waste).
  • The cellulous (Carbon) material is initially broken down by bacteria (followed by fungi and then manure worms).

    Shredded paper

  • Bacteria need Nitrogen (+ Hydrogen and Oxygen) to make their proteins and build there bodies.
  • If we build a compost heap of just high Nitrogen material (e.g. chicken manure with a Carbon Nitrogen ratio of 6 – 1) it will break down eventually to a Carbon Nitrogen ratio of 10 -1 by losing its excess Nitrogen in the form of ammonia and nitrous oxide into the air, both green house gasses, as well as wasting a very valuable plant nutrient.
  • Use manures and high Nitrogen green waste, such as grass mowings, etc as activators to help brake down high Carbon material, rather than applying direct to the soil which is a waste.
  • If we build a compost heap solely of high Carbon material it will take a long time to break down as there will be very little Nitrogen to feed the bacteria which do the work and the resultant compost will be poor in plant nutrients.
  • So, we need a combination of both high Carbon material and high Nitrogen material in the right proportions.
  • If possible, save up enough materials to build a 1 cubic metre heap, or bigger, but you could get away with ½ cubic metre.
  • As a rough guide, build in alternate layers of 20cm high Carbon material then 5cm of manure (or grass mowings, green weeds, or a sprinkling of dried blood, dried fish meal, dried blood and bone, etc), then another layer of high Carbon material and so on.
  • The heap should be made loosely to allow air into the heap and built on a base layer of twigs or sticks too allow air to enter via the bottom.
  • With 20cm high carbon material to 5cm high Nitrogen material, there will be enough initial Nitrogen to feed the bacteria, but not enough to finish the process, so the bacteria will be forced to look for the extra Nitrogen from the air which is 78 per cent Nitrogen.
  • As a result, if compost is made correctly one can end up with more Nitrogen (a valuable plant food) than one put in, in the first place (up to 20%) – an old trick of the trade and one not often understood.
  • It is not essential, but if you add beneficial bacteria and fungi to your heap this will help to produce a better product. ‘Compost Activator’ by Blooming Good – is one such product.
  • Organic material will not rot without moisture (not sopping wet). Dry material will just sit there unchanged. So, add water if necessary as you build the heap.
  • The process of decomposition has a tendency to create acidic conditions, so to keep the heap sweet, lightly sprinkle hydrated lime (which is fast acting) in the middle of the high Carbon layers, not against the manure as it will react causing a loss of Nitrogen. One can also add wood ash from untreated wood, which contains Potassium and Calcium. The Potassium in wood ash is in the form of an assorted batch of Potassium Carbonate molecules, which are converted in the compost heap to more stable and usable forms. The addition of 1cm of healthy top soil to this layer is also useful, as it contains micro-organisms that help to break down the compost material.

To simplify: Build the heap in layers –

Compost Base

Compost Base

  1. Start with a 15-20cm layer of course prunings, cabbage stems, sweet corn stems etc, on the bottom for air.
  2. Cover with about 6cm of straw or equivalent waste.
  3. Add 20cm of high carbon material such as hay, straw, or other course garden waste and moisten with water if dry.
  4. Add 5cm of high nitrogen animal manure, green weeds, grass mowings, or a sprinkle of ‘blood and bone’, ‘blood fish and bone’, fishmeal, dried blood or collected urine.
  5. Continue adding layers 3 & 4 until finished.
  6. If you are using hydrated lime sprinkle it in the middle of each high carbon layer away from the manure.
  7. If any of the material used is dry it will need watering to make it moist – dry material will not rot, it needs moisture.
  8. Ideally after 6 weeks turn the heap. Turn the outside to the inside, the inside to the outside, the top to the bottom and the bottom to the top. This is your chance to correct any problems that may have arisen. If parts are too wet and smelly, mix in some dry material and a sprinkling of lime – if to dry, add some grass mowings or some water.
  9. After 3-4 months in summer, or 6 months in the winter, it will be ready to use at 1 to 2 buckets per square metre. Lightly fork in to the soil. For people who prefer no-dig gardening – spread the compost on the surface and cover with some mulch to keep the compost from drying out and the sun killing off the micro-organisms. For pumpkins, squash, zucchini and tomatoes – dig a hole, 30cm square and deep and half fill with compost trodden down. Fill the rest with top soil and plant your plant. When the roots hit the compost it will take off. For potatoes you can take out trenches 1 fork depth, put in 8cm of compost, spread about 3cm of soil on top and lay your seed potatoes, sprouts up, on the soil layer and back fill the trench with soil from the next trench.

For Even Better Quality Compost:

To get even better quality compost you can even increase the initial Carbon/Nitrogen ratio of your compost to 60:1! This idea has come about from the work of Steve Rioch who experimented over several years in the US, along with the staff at ‘Ecology Action’, California, who have compiled a booklet called ‘Grow Biointensive Composting & Growing Compost Materials’ by Ecology Action Staff in conjunction with John Jeavons. I have been using this method for several seasons to great effect. They found that a higher Nitrogen content in the heap will produce ‘hot compost’ with temperatures of 60-650C, resulting in temperatures where the biological activity is so intense that the excessive fermentation results in a loss of Nitrogen and organic matter as Carbon dioxide, as well as killing off of the very micro-organisms that are needed in the secondary cooler stage of composting, which is important for producing humus, those very micro-organisms by the way that will also be retained in the finished compost to help build up the soil life.

Using an initial 60:1 Carbon/Nitrogen ratio leads to cooler composting with maximum temperatures around 570C for the first 2 weeks, dropping significantly after a short time to around 490C for a longer period, and is much less destructive, producing higher levels of humus, plant nutrients and essential micro-organisms in the finished product.

Another major change has been the addition of topsoil in layers, which the first time was worrying, because it left small craters in my vegetable beds, but then I realised it would be returned later – so no problem. Adding thin layers of topsoil to a heap helps to slow down the heating, and the soil also helps by binding onto nutrients, especially Nitrogen, later available for the plants, as well as adding essential soil micro-organisms that help the composting process.

As a result, preliminary tests that they did at Ecology Action are very interesting that at first seems counter intuitive. Three equal sections of garden had the same amount of compost applied.

  • Compost made on a 60/1 CN ratio
  • Compost made on a 45/1 CN ratio
  • Compost made on a 30/1 CN ratio

The 60/1 made compost yielded twice the crop as the 30/1 made compost, and 50% higher than the 45/1 made compost. These trials are still in the early stages to be definitive, but these results are impressive nonetheless.

Another major change to the way I am making compost is to make the layers thinner. In the past I would build the heap with alternate 20cm layers of high Carbon material sandwiched with a 5cm layer of greens and/or manure as already described. I now realize that the centre of the high Carbon material was not in contact with the manure layer. Often in the past the centre of the 20cm high Carbon layers was slow to rot, with good reason.

I have also started to use a biological compost activator watered onto the layers as it is built. Adding a biological activator plus the soil layers ensures there is a good collection of beneficial micro-organisms in the compost. Blooming Good’s ‘Compost Activator’ I have found to be very effective.

I have now started to use shallower layers by using a 20-litre bucket as a measure. For my compost 1 metre x 1 metre square bins I apply 3 buckets of high Carbon material (approximately 6cm thick), then ½ bucket of  ‘greens’ (approximately 1cm thick), then a ¼ bucket of topsoil (approximately ½ cm thick). As a result the different contents are in closer contact and better interaction results. This method has produced more bulky compost, which looks more like composted manure.

The only problem I foresee with this cooler composting is that weed seeds will not be killed effectively. A temperature of 600C and above is necessary to kill the more difficult weed seeds. However, if you try to ensure that no seeding weeds are added to the compost, or old hay, or horse poo, which has grass and other seeds in it, it should not be a major problem.

Difficult Materials:

  • Cabbage, Broccoli and Brussel Sprout stems and roots
  • Sweet Corn stems and roots

These are difficult to compost without preparing them first.

  1. Dig them up a knock the soil off the roots.
  2. Smash them with a heavy hammer or block hammer on a bulky timber. This will allow the bateria and fungi to penetrate and rot them down much more easily in the compost heap.
  3. Alternatively, take out a trench 20cm wide and deep where your spring sowing of runner beans are to grow. Dig the brassica or sweet corn stems up at the end of winter and smash them as above and then spread them along the bottom of the trench to make a lose layer about 10cm thick. Cover them with kitchen waste and fill in with soil. As the kitchen waste decays between the stumps the soil will sink and will need topping up with more soil. After your crop of runner beans have finished you will find the stumps have turned to lasting black humus helped by the surplus nitrogen fixed by the bacteria in the bean roots.

Materials to avoid:

Meat, fish and dairy products, dog and cat poo, oils and fats, diseased plants, bamboo, flax and cabbage tree leaves, nasty weed roots (convolvulus, couch grass, etc), weeds that have seeded.

Problem Solving:

Smelly compost: This usually occurs with small gardens, where there is not enough high Carbon material to add, and there is only grass mowings, green weeds and kitchen waste – all of which are high in Nitrogen. The compost will                                                start to smell and flies appear if you have put too many Nitrogen rich materials in the compost, and/or if it is too wet. This stops air getting to the heap and it becomes acidic.

Solution: Try to get hold of a small bale of organic or unsprayed dry straw or hay, dry leaves, or a large bag of shredded paper from an office. Turn the compost adding some dryer high carbon material, sprinkling some garden lime on the layers as you rebuild it to neutralise the acidity.

Dry unrotted compost: This is more likely to happen in the summer, especially if the compost site is in a sunny place, or if you have added a lot of dry material in the first place.

Solution: Turn the compost; lightly watering each layer as you turn it, along with grass mowings or other high Nitrogen materials to kick starts the compost.

My compost is not braking down: This is usually because there is not enough high Nitrogen rich materials in your compost, or it has dried out.

Solution: (see 2).

Rodents are getting into the compost: This is usually due to adding kitchen waste, which instead can be composted using the Bokashi bucket system (see below), but they may be just setting up camp in the warm compost.

Solution: Add grass clippings to the compost to increase heat and turn regularly, or set traps.

Having followed these instructions and gradually gained experience, you will make valuable humus for your soil. The heap will heat up over a few days to around 50o – 60oC or even 70oC although the lower temperature range is better. The hot air will rise up through the heap drawing in fresh Nitrogen rich air from the bottom and sides.

Carbon/Nitrogen ratio of some compostable materials

~ 6:1 ~ 12:1 ~ 25:1 ~ 50:1 ~ 100:1
Blood & Bone Vegetables Summer grass Cornstalks (dry) Sawdust
Meat scraps Garden weeds Seaweed Straw (grain) Paper
Fish waste Alfalfa hay Legume hulls Hay (low quality) Chaff
Rabbit manure Horse manure Fruit waste
Chicken manure Sewage sludge Hay (top quality) Corn cobs
Pig manure Silage Tree bark
Lawn Mowings Cow manure


The compost heap can be a great propagator of nasty weeds if you try to compost weeds such as couch grass, convolvulus roots, dock and dandelion roots, oxalis bulbils and other such nasties. You can put them in the middle of a large well made compost heap, but there is no guaranty they will get cooked properly.

However, do not throw them away; they contain valuable plant nutrients, for instance couch grass is high in Phosphorus. A more sure way is to drown them in a tub of water, preferably with a tap attached to the bottom. Two tubs used alternately are best. After a minimum of six months, the roots should be dead. To ensure a healthy breakdown, with little smell, add a tablespoon of liquid EMNZ which contains essential beneficial micro-organisms (see:

The resulting juice can then be used as an activator on the compost layers and the dead material added to the carbon layers. Alternatively put the weed roots in a black plastic bin liner, add a little water, tie the open end and leave somewhere in a corner for six to twelve months. Another rule of composting is not to add seeding material in case the weed seeds do not get cooked in the heat of the heap.

The End Product

Much emphasis has been placed on the Carbon/Nitrogen ratio of compost materials and the finished product – humus. This is important understanding when building compost heaps, but it has to be remembered, there is a lot more to the finished product than just Carbon and Nitrogen. Humus is a living substance, it is a mixture of compounds and complex organic chemicals of plant, animal, or microbial origin that has many functions and benefits in the soil. Good quality humus will contain, and has attached to its particles, a whole range of valuable nutrients such as:

Calcium, Potassium, Sodium, Phosphorus, Nitrogen, Sulphur, Magnesium, Copper, Boron, Iron, Manganese, Copper, Zinc, Aluminium, Chromium, Cobalt, Iodine, Molybdenum, Selenium, Tin, Vanadium, Nickel, Fluorine and Silicon.

It also contains important enzymes and plant hormones, fulvic and humic acids + beneficial bacteria, protozoa, fungi, muco-proteins – etc, etc

However, it is not enough to see humus purely in terms of its constituent parts; it has many qualities – as Sir Albert Howard described it:

  • Humus is not static, but dynamic, since it is constantly being formed from plant and animal residues and is continuously decomposed further by micro-organisms.
  • Humus serves as a source of energy for the development of various groups of micro-organisms.
  • Humus has the capacity to hold onto plant nutrients until they are needed by the plants.
  • It also combines with other soil constituents.
  • It swells as it absorbs water and can hold the equivalent of 80–90% of its weight in moisture, releasing it gently to the plants. This greatly increases the soil’s capacity to withstand drought conditions.
  • The biochemical structure of humus enables it to moderate – or buffer – excessive acid or alkaline soil conditions.
  • The dark colour of humus (usually black or dark brown) helps to warm up cold soils in the spring.
  • Humus also acts as cement. During the humification process, microbes secrete sticky gum-like mucilages; and these help to form a good soil crumb structure (tilth) by holding particles together and allowing greater aeration of the soil.

Further Reading:

COMPOST BINS, BOXES (bought or home-made?) OR OPEN PILES?

What containers you decide to use (or none) entirely depends on your circumstances – whether you have a small town garden with neighbours, live in the country, have a life-style block or small farm, or work with others to grow food collectively in a community garden or landshare scheme – it is basically a matter of scale and how tidy you need or want to be. We will start with the smallest versions of bins and work up to large scale free-standing compost piles.

  1. Garden Wise type: The smallest type for small town gardens is a simple round or box shaped plastic bin, about a metre high, smaller at the top and tapering out towards the bottom, with a lid and often an access door at the bottom. The value of these types is that when full, one can lift the bin off the pile easily to start a new pile next to the original one. Another benefit is that composting is kept tidy, which is often important if you live next door to neighbours in a town or city. Some councils, such as Nelson and Tasman, inNew Zealand offer a subsidy to locals to buy a bin in order to encourage composting and cut down organic waste ending up in land fill. It is worth checking in your area or country to see if there are similar schemes. Whether you pay full wack, or get a subsidy, it will cost money.
  2. Tumbler: The next type is a tumbler, which is a barrel which is turned regularly, to which you add compost material to over time. This type does not allow hot composting, because they are not big enough and are too exposed and lose what heat is generated and they need turning every few days. The only advantage is that if you have a lot of waste food, especially cooked food including meat, then at least the tumbler compost bin will be vermin proof. Apart from that I personally see no value in spending money on such a product.
  3. Earth Maker type: These types are large, hugely expensive compost bins with several sections where the developing compost is moved down into different compartments where it continues to mature – ending up in the bottom in a finished state. When I see this kind of overcomplicated, over thought out and over designed piece of equipment, I wonder what planet industrial designers are living on! Certainly, this type of oil made over sophisticated piece of equipment has nothing to do with sustainability.
  4. Wooden Bins: There are flat-pack versions you could buy, but you can make your own for little or no money! Just Google “build your own wood compost bin” and you will get many ideas and instructions, including making them from free 1 metre square pallets that some shops are happy for you to take away – just ask them. This is how we have built a three bin system atWaimaramaCommunityGardens, and how I built my own three bins at home. By building a three, or two bin system, you save on wood, because the sides are shared. Also you need to have them cheek to cheek so you can turn your recently made compost into the second bin next to it and then turn the finished product into the final holding bin until you need to use it. However, you can get away with two.
  5. Compost Heaps: On larger properties, community gardens, farms, etc; where large heaps of 2 cubic metres or more at a time are made, then open piles up to 1½ metres across, up to 1½ metres high and as long as you like can be made without sides. There will be little unbroken down material on the outer layer and this can be added to the next heap – or turned in if you turn the heap. I usually cover the top with a 150mm layer of straw to finish off the heap, which allows the top layer of compost to keep moist and rot down properly. This is how we make the bulk of our compost atWaimaramaCommunityGardens and how I made 30 tonnes a year on our farm – no problem.


These are crops that are grown to provide carbon rich material to make compost. They may also produce edible seeds or fruit at the same time (such as maize), or just produce bulk material. They can be grown as part of a crop rotation system, or be a perennial crop that is cut regularly. To be entirely self-sufficient in carbon rich compost material it has been estimated that one needs to grow compost crops on an area 60 per cent of ones cropping area to add to the waste material from cropping, for instance, if you are growing 50 square metres of crops, including fruit, then you will need to grow 30 square metres of carbon crops, or 80sq metres in total. Below is a list of compost crops that you could grow:

  •  Amaranth – bulky material, high yield + edible seeds
  • Jerusalem Artichokes – perennial crop, bulky material, edible roots
  • Maize – bulky material, high yield + corn cobs for eating fresh or for drying and processing.
  • Naked Barley – straw + edible seeds (no de husking necessary).
  • Naked Oats – straw + edible seeds (no de husking necessary)
  • Quinoa – reasonably bulky material + edible seeds
  • Sorghum – very bulky material + edible seeds
  • Sunflowers – bulky, high carbon material, but the seeds are very difficult to de-husk, but great for poultry – cut heads and let the poultry self harvest.
  • Wheat – straw + edible seeds
  • Barley, Oats and Wheat – can be grown together or separately and cut at the flowering stage.
  • Globe Artichokes – very bulky tough grey-green stems and leaves + edible flower heads.

All these crops can be grown solely for their carbon material by harvesting them just before flowering.


Another way of accumulating carbon in your soil is the use of decidious tree lewaves. The use of peat, dug up from peat bogs, is both environmentally damaging and not sustainable. If you can save enough leaves you will be self sufficient and have an even better product than peat in the form of long lasting lignins and hemi-cellulouses, which makes the longest lasting humus.

If you have a dark, out-of-the-way corner of your garden where nothing will grow, that is a good place to build your leafmould heap. To stop the leaves blowing around while they rot, drive in some stout posts at the crners of what will be your heap and then attach chicken wire to the posts to make an enclosure. Just pile the leaves into the container – nothing else. Making leafmould is not the same as composting. Do not add anything else, just leaves. A leafmould heap does not heat up; it just rots gently through the natural process of fungi breaking the leaves down as it would on the floor of a forest.

After one year it will be broken down into beautiful long lasting humus, high in Potassium and Phosphorus, which can be use as mulch around fruit bushes and trees – their natural food – and as a useful much between rows of seedlings like carrots, and finally as an important ingredient of home-made seed and potting compost.

For every two and a half cubic metres of fresh leaves you will get one cubic metre of leafmould, or roughly half a tonne – well worth while.



One of Nature’s greatest helpers is the earthworm. They are invaluable for the production of top soil, soil crumb structure and plant nutrition. For gardeners and horticulturists they are both valuable allies and at the same time a real test of the health of our soils – the more healthy the soil the more earthworms – the more earthworms the more healthy the soil.

There are two types of earthworms that are important. There is the manure, or tiger worm Eisenia foetida, that ingests fresh animal manures and fresh plant waste and then there are earthworms which live in soil, which are next in the food line. Manure or tiger worms are at the start of the humus food chain and must not be overlooked for the valuable role they play. These are found in cow pats, compost and muck heaps and in the leaf litter of woodlands, in fact wherever there are high levels of reasonably fresh organic waste. These worms are the first in line when it comes to the process of breaking down organic waste into plant food. They will appear miraculously into a cooling compost to help apply the finishing touches to the composting process. They will crawl considerable distances to find cow pats and other fresh organic waste. These are the ones used in worm farms for producing worm compost and liquid worm juice fertiliser.

Here in New Zealand there is at least 171 species of native earthworms and 23 non-native species. Native earthworms are mostly confined to areas where the soil is disturbed less often – forests, old gardens, hills and mountains, as a result they are essential to the overall ecosystem and to upland pastures, but they are generally not so useful for intensive horticulture and agriculture. The most useful earthworms in intensive situations are the Lumbricidae species.

Aporrectodea caliginosa is probably New Zealand’s most common lumbricid as well as in many Northern hemisphere countries. Aporrectodea caliginosa also know as the grey worm has a body length of 50 -150 mm. They measure about 4mm around. Colours in spite of its name can range from brown to greenish. As they need moist soil, during summer it has a period of dormancy staying 30 centimetres below ground in tunnels. It is most active during the spring and autumn. They feed in depths from 20 cm to right up to the surface. Leaf litter and other decomposing organic material mixed in the soil provide most of their food. Allolobophora caliginosa tends to feed on organic matter below ground, depositing their casts on the surface, thus building up a fine top soil and carrying nutrients that have washed out of the top soil back to the surface. The fine top soil builds up over many years and the larger stones find their way to the bottom of the topsoil just above the subsoil, thus helping to provide a drainage layer at the base of the topsoil. This species is one of the most widely distributed earthworms. It thrives in pastures, gardens and forest as well. It can be found in every type of substrate even in the poorest sandy soil. It is adapted to live in a disturbed environment, which is one of the reasons it is so useful for our purposes.

Other worms deposit their casts within the soil. Both types are essential in creating a stable crumb structure. One can say without fear of contradiction – as Darwin observed – that every morsel of topsoil has passed through a worm’s digestive system numerous times and they have been one of the major creators of top soil over millions of years.

The earthworm is basically made of rings of muscles with a mouth at one end and an anus at the other. In between it has a digestive system with a few interesting additions, such as a gizzard containing grit for grinding up food like a bird, and a special gland that secretes lime. The worm as it burrows through the soil ingests soil, organic matter and grit. The earthworm does not digest plant matter with enzymes. Instead it employs microorganisms for this energy intensive task. A unique range of microbes are incubated within the earthworm and are excreted amongst the castings to introduce these organisms to the soil. That is why growers have achieved such good results from earthworm juice (water that has passed through the worm beds and accumulated these organisms). They also eat fungi and protozoa as the soil passes through their digestive system. In the process it intimately mixes the soil constituents, at the same time turning nutrients that were unavailable to plants into available water soluble minerals, and turning plant remains into more valuable humus.

And do they shift some soil! Various estimates suggest that a healthy worm population will swallow, process and excrete a prodigious 40 tonnes of dry earth per hectare every year, which is not surprising because the number of worms in a healthy pasture can be up to 1,250,000 per hectare (506,073 per acre), weighing up to 650 -1100 kg per hectare (579 – 980 lb. per acre.

Other worms deposit their casts within the soil. Both types are essential in creating a stable crumb structure. One can say without fear of contradiction – as Darwin observed – that every morsel of topsoil has passed through a worm’s digestive system numerous times and they have been one of the major creators of top soil over millions of years.

Although true earthworms will not survive in acid soils (anything below pH 5), they have the ability to maintain a neutral soil themselves by excreting calcium surplus to their requirements from a special calcium gland in their gut. The resultant pH of their casts is neutral. Some of the calcium they ingest is in an insoluble form, but during digestion it is converted into a soluble form, therefore increasing soil pH, and helping to maintain the essential crumb structure of a healthy soil. This is because calcium irons have a positive electrical charge which attracts the negatively charged particles of clay which coagulate around the calcium particle forming a crumb. Because calcium is the most important nutrient and it is removed with every crop. Earthworms are like little lime works; they have a calciferous gland that adds calcium carbonate to everything that passes through them. They are also burrowing deep in the profile bringing calcium and other minerals up into the root zone. In other words the earthworm by its activities – whilst continuously helping to create and maintain the environment in which it likes to live and prosper – also benefits a wide range of other soil organisms and plants, many of which also provide food for the worms.

Not only that but the worm adds to this mix a gluey mucoprotein which glues the soil particles together forming a crumb which is able to resist the eroding action of rain that either hits it directly, or as it flows through the soil. This ensures the crumb retains its stability for a considerable period of time.

Earthworms derive their nutrition from many forms of organic matter including decaying plant parts, decomposing remains of animals, and living organisms such as nematodes, protozoa, rotifers, bacteria, fungi. One of their favourite foods are protozoa and one of the ways we can encourage an increase in our earthworm populations is to encourage protozoa. The best way is to make an aerated lucerne hay ‘tea’ (see the compost tea section). By watering this ‘tea’ on your soil, the protozoa population will increase and so will the worm population.

Worms can produce their own weight in castings every 24 hours – up to 300 tonnes of humus rich castings per hectare every year where there is a healthy soil population! During the digestive process, many insoluble minerals are converted to a plant-available soluble form and long-chain molecules such as cellulose are partially broken down by bacteria in the digestive tract. Also the gut of the earthworm is the ideal environment for soil bacteria to proliferate and therefore the worm’s casts are much richer in beneficial bacteria than in the surrounding soil. The earthworm does not digest with enzymes when plant matter passes through its system. Instead it employs microorganisms for this energy intensive task. A unique range of microbes are incubated within the earthworm and are excreted amongst the castings to introduce these beneficial organisms to the soil. The analysis of worm castings reveals that the number of beneficial bacteria in the ejected worm casting is much higher than in the material ingested by the earthworm.

Investigations in the US show that fresh earthworm casts are 1.5 times richer in available Calcium than surrounding soil, 5 times richer in available Nitrogen, 7 times richer in available Phosphorus, 11 times richer in available Potassium and 3 times richer in available Magnesium than the surrounding upper 150 mm of soil.

Once more we see a self supporting co-operative process at work – a “give and you shall receive” deal in nature. The earthworm is seeking as much plant matter and beneficial micro-organisms as possible because that is what it eats. The bacteria it excretes into the soil sponsors the production of more biomass, which means more food for the earthworm. These bacteria are also a food source for protozoa which, in turn, are the favourite food of earthworms. In this manner, the system becomes self supporting as is the case with many natural systems.

To sum up, the worm casts are much richer in available plant nutrients, have some easily available Calcium in the cast, are richer in more valuable humus and have much higher bacteria content than the original ingested soil. We now begin to see why the earthworm is one of the most fantastic of all soil creatures, with its importance in the creation of soil structure, and in its ability to make food available for plants, but there is more!

To reinforce the walls of their burrows they line them with slime and organic material which attracts other organisms which serve as a food source for the worms. As they move through their burrows they vacuum this supplementary food en route. And don’t plant roots also enjoy the results! In their search through the soil, plant roots find an aerated tube with easy access and plenty of available food. The worms create perfect passageways to improve gas exchange and improve water infiltration, so that when it rains the water runs conveniently down the tunnel to water its roots – what more could a plant want?

Well it is even better than that! Dr. Stewart, professor at Aberystwyth Agricultural in Wales, a renowned soil scientist and expert on earthworms, did research into the ideal soil crumb size. He considered that there were two main factors that would determine the size of the perfect soil crumb. The first was determined by the ideal air to water ratio in the soil. This in turn is determined by the surface area of the crumbs in relation to the air spaces between them, and the nature of water’s surface tension. After rain and the excess water has drained out of the sponge like soil, some water remains as a film on the surface of the crumbs. If the crumbs are large there is too much air and not enough water. If they are too small there is too much water to the amount of air, indeed if too small, there is no room for the air at all. The other factor Dr. Stuart considered important was that if the soil crumb was too big, oxygen could not penetrate to the centre of the crumb and the middle would become stagnant and anaerobic, which is not ideal for plant roots and most beneficial micro-organisms. Having used these criteria Dr. Stuart calculated the perfect crumb size and to his amazement, found that the size of the crumbs created by worms were exactly the same as his ideal one!


How do you recover your earthworm populations to profit from this wondrous workforce? There are several foods that stimulate earthworms, including protozoa and fungi.

1. Increase the soil humus to a minimum of 5 per cent. The worms themselves will help greatly to increase the humus content even higher, as they are the best creators of humus, but they need a helping hand at the beginning

2. Create the ideal soil nutrient balance, especially the Magnesium/ Calcium balance, which is the single most important ratio in the soil because it governs oxygen delivery (see the section – IDEAL SOIL MINERAL BALANCE)

3. Grow regular green manure crops to provide fresh organic material to the soil, To feed worms directly and to increase the bacteria that protozoa eat – because worms love to eat protozoa

4. Also make and apply Lucerne tea to your soil regularly to encourage protozoa

5. Reduce physical cultivation of your soil as this disrupts worm activity and their burrows. It also interferes with the growth of fungi – one of the worms favourite food

6. Anything that increases the number of fungi in your soil will boost earthworm populations because fungi are a major food source for these creatures. Humic acid is the most powerful promoter of fungi followed very closely by kelp. Ironically it is worm juice and vermicaste from worm farms that are high in humic acids, but well made compost and compost tea are a valuable source

7. Worms love liquid fish fertiliser. They will come from far afield to enjoy this concentrated mix of protein, fatty acids, carbohydrates and minerals. The important thing is that the liquid fish fertiliser still contains the full oil component, as the fish oil is a major attractant.


This is a very useful way of composting kitchen waste. Waste food and food trimmings in an ordinary compost heap can attract rats and mice, but in the confines of a worm farm container, this can be avoided. The resultant digested compost is much richer than the average compost, as already discussed.

How to Start a Worm Farm:

• Buy a worm bin or make one easily out of plastic dustbins, old baths, stacks of old tyres, or larger containers for commercial establishments

• Have drainage holes, or pipe in the bottom to collect the precious worm juice

• Choose a site sheltered from sun, wind & rain. Carports, or sheltered porches are ideal

• Spread a 10-12cm layer of bedding – dampened hay/coconut fibre/shredded cardboard or paper

• Purchase your worms, 1,000 (250g) or even better 2,000 tiger (compost) worms – not garden earthworms

• Put worms into their new home and add the first food scraps

Keeping it Going:

• Keep the compost damp, but not sodden. Add dry leaves or torn up paper if it gets too wet

• Add food scraps regularly

• Don’t overfeed – if the worms can’t keep up the food scraps will ferment, which is not what the worms, or you want

• Regularly empty collected worm juice, dilute 1:10 & use as liquid plant feed

Manure Worms Like:

• Most fruit & veg scraps

• Potato & other peelings

• Cooked food (not to much)

• Coffee grounds & tea bags

• Horse, sheep, goat etc

• Newspaper (not shiny)

• Vacuum cleaner dust

Manure Worms Don’t Like:

• Too much – spicy foods, chili, garlic onion etc

• Too much – meat & milk products

• Too much – flour products, bread etc

• Citrus waste

• Course garden waste

Extracting the Worms:

When the waste is thoroughly broken down into dark crumbly compost, remove the fresh waste where most of the worms will be and place aside. Take out the finished compost and pile it up in a cone on some plastic sheet in the daylight but protected from the rain. The worms will naturally move away from the light and each day you can take 3 to 5cm of compost off the pile to bag up. Eventually you will have saved the majority of the compost free of worms which will be huddled at the bottom of the remaining compost. You can then add them back to the worm bin along with the fresher material set aside to start the process again.

To Use:

The rich compost is great to use in making potting compost, or mixing in a handful to the soil where you are planting out seedlings. It is also useful to mix a bucket of worm compost per square metre into the top few centimetres of soil where you will be planting heavy feeding plants, such as brasicas, the onion family and sweet corn.

The worm juice is a very useful rich plant food. There are conflicting suggestions on the dilution, this entirely depends how dark (rich), or pale it is. The best suggestion is to water it down to week tea colour.

A Typical Worm Juice Sample Analysed:

  • Healthy bacteria 100,000 CFU/ml – these include high levels of Nitrogen fixing bacteria
  • Nitrogen 64 mg/L
  • Phosphorus 21 mg/L
  • Potassium 940 mg/L
  • Sulphate 82 mg/L
  • Calcium 62 mg/L
  • Magnesium 150 mg/L
  • Sodium 120 mg/L
  • Copper 276 ug/L
  • Zinc 105 ug/L
  • Manganese .26 mg/L
  • Iron 1.5 mg/L
  • Boron .41

Also found in worm juice and compost there is high levels of humic acid which encourages the growth of beneficial bacteria as well as fulvic acid which encourages the growth of beneficial micchorizae fungi.


Having healthy levels of mycorrhizae fungi in a soil is an essential part of building high soil carbon levels, creating high soil fertility, optimum supplies of plant nutrients and healthier soil life and healthier plants (see section: The Living Soil – Mycorrhizae Fungi).

Following all the approaches in this section will help to encourage healthy levels of mycorrhizae fungi in your soil, but here are some other important tips and practices which definitely help:

•     Stop using water soluble chemical fertilisers and pesticides, especially fungicides.

•     Mycorrhizae prefer a pH range of 5.5-7.5 – so aiming at 6.4, which is ideal for most food crops, will also be beneficial for the fungi.

•     Reduce soil cultivation to a minimum, because the fine mycelial threads (hyphae) are easily broken. Hoeing and other cultivations near the surface are OK, and when you are planting out seedlings take out only as much soil as is needed to plant them. A bulb planter is a useful tool to use for transplanting.

•     Thick mulching over a wide area will reduce the feed plants and the mycorrhizal fungi. Living mulches of red clover, deep rooting herbal orchard mixes and grasses under fruit and nut trees will keep the fungi and trees healthy.

•     Sow red clover in beds where brassicas and beets are grown exclusively. Clear away a small patch of clover when planting out the brassicas to avoid competition from the clover. I have had good results using this technique.

•     When planting out seedlings, or bigger plants, add the roots of non-invasive weeds from the same plot or area to the planting hole, as the roots should have mycorrhizae fungi and spores in them.

•     If the soil has been greatly disturbed by building activities, conventional farming using chemical fertilisers and pesticides, regular deep ploughing or digging etc – then using a mixture of both endo and ecto-mycorrhizal spores should be very helpful. If there are sites in the local area which have not been conventionally farmed (preferably mixed pasture), then taking soil samples from these areas and applying them to the affected site should re-colonise the local strains of mycorrhizae. You can also buy spores from reputable companies. I use Environmental Fertiliser’s Bio-Vam. Bio-Vam is a dry blend of endo- and ecto-mycorrhizal fungi, with the addition of other beneficial soil microbes that is a constituent in ‘EF Nature’s Garden’ composted balanced fertiliser that I use.

HOW TO MAKE BOKASHI COMPOST (+ Essential Microorganisms)

At the beginning of the nineteen eighties Professor Teruo Higa, working as a professor and researcher at Ryukus University in Japan, Professor Teruo Higa was one of the instigators of isolating, growing and utilising micro-organisms in agriculture and horticulture. One day while working he spilled some microorganisms near a few shrubs and some days after he noted that the plants were growing abundantly well. With this he continued his studies to find out what was the best combination of beneficial micro-organism until EM (Essential Micro-organisms) was formally introduce as a soil conditioner.

In 2007, he was recognized as Honorary Professor atRyukusUniversityand as Professor atMeioUniversityin OkinawaJapan. In this same year, Dr Higa took up the position as president of the ‘International Institute of EM Technology.
EM is most widely known in the form of Bokashi, a dry mixture of bran and or sawdust with added spores of:

  1. Lactic acid bacteria
  2. Yeast
  3. Photosynthetic bacteria
  4. Actinomycetes and other types of micro-organisms

This is used in a double box with an air tight lid in which is placed a household or commercial kitchen’s waste food and vegetable trimmings. The top box has holes in the bottom to allow nutrient rich liquid to pass to the bottom box. Anaerobic fermentation takes place, which starts the composting process. The composting process is then completed when the contents are buried and mixed with some top soil where vegetables are to be grown.

Liquid EM can be used in horticultural or farming establishments to compost down large amounts of organic waste, which can then be ploughed into the soil before the sowing, or planting of crops. It can also be used as an activator for your home compost heap. Dilute 1-1,000, add same amount of molasses to feed the micro-organisms and use 3 litres to every cubic metre of compost.

Another use of liquid EM is as a disease preventative foliar spray at 1-100 with molasses. The micro-organisms out compete disease fungi and bacteria, reducing their ability to take hold.

The main use of liquid EM is as a soil activator. I see this is very useful where soil has been denuded by conventional chemical techniques, or on new building sites. Here I suggest some caution. As has already been said, plants excrete waste sugars, along with other things, from their roots which encourage huge populations of soil microbes and beneficial fungi around their root zones, which then make nutrients available for the plants, but only when they need it and only around the root zone. So, for me, the over use of liquid EM plus equal amounts of molasses added to a whole area of soil is not only overdoing it, but I would worry about the resulting rush of nutrients being released throughout the soil profile which cannot possibly be utilised by the plants at that time and possible loss of the excess nutrients being washed away. To use EM on soil without increasing humus levels, achieving soil nutrient balance and all the other practices to optimise conditions for a healthy soil life, is like regularly taking pro-biotics whilst still consuming too much alcohol and junk food.

However, EM is a very useful technology and I use it regularly to help brake down green manures, add to tubs of liquid manures to cut down smell, cut down unhealthy fermentation and loss of nutrients and to improve the finished product. I also use it as a foliar spray to help control disease. On a farm or industrial scale EM is exceptionally useful for processing large amounts of household and waste from the wine industry, beer making and other industrial organic waste into humus to enrich the soil. It has also been shown to be useful in composting human waste safely.




As far as I am concerned, growing comfrey is a vital part of growing food sustainably and helping to create a healthy vibrant soil and nutrient dense food. Comfrey (Symphytum officinale) is a member of the Borage family. It is a perennial plant with very deep roots, and is a natural mineral mine, bringing up minerals from the sub-soil way beyond the reach of anything else but a tree and making them immediately available for crops, unlike a tree that locks away the minerals it gathers in its wood. Comfrey has a deformed flower structure which rarely sets seed, so there is little risk of it spreading as seedlings.

Comfrey has large hairy leaves, which is the part used by gardeners and horticulturists as valuable manure rich in Potassium and so much Nitrogen in its protein that its Carbon/Nitrogen ratio is 9:1 almost the same as well rotted garden compost at 10:1. Comfrey has a little more Nitrogen, a little less Phosphorus and over twice the Potassium of horse, or cow manure and slightly more Potassium than garden compost.

Comfrey leaves are a balanced fertiliser for potatoes, tomatoes and other fruiting plants, such as squash, pumpkins, zucchini, cucumbers, all the berries and other fruit except citrus, which likes less Potassium and more Nitrogen.

There are several ways of using this valuable fertiliser:

  • Cutting the leaves and letting them wilt first, before using them as a mulch around fruit bushes and trees.
  • Mixing the wilted leaves into the top 5 cm of top soil, as you would do with garden compost, before planting a crop (eg. potatoes).
  • Making liquid comfrey fertiliser to feed fruiting vegetables, bushes and trees – (except citrus which prefers Nitrogen rich fertiliser) – (see: BUILDING FERTILITY – Liquid manures).
  • Planting comfrey plants around the drip line of fruit trees and nut trees to cut regularly to mulch and feed the trees, especially in a forest garden (except citrus which prefers red clover).

Where to Grow:

If you already have a plant, or you have a friend with some, you will notice there are several growing points with thick long roots attached. These can easily be separated by pushing a spade down between the growing points and digging them out. Alternatively you can purchase plants, or offsets.

Comfrey is a perenial with very deep roots, so wherever you plant it, it will be with you for a very long time. You can plant the root offsets with a growing point in odd corners, or in a forest garden around trees, or around the drip line of free standing fruit trees, which will not interfere with the shallow feeding roots of the trees as the comfrey roots dig very deep bringing up minerals and nutrients that have been washed out of the top soil. To feed the trees, cut the comfrey leaves before the plants flower and leave them on the ground around the trees. We like to use comfrey in the above way, but we have always had a specially prepared comfrey bed for larger scale production as well. On our farm we had a comfrey bed around 35 x 60 metres (2,100 square metres) – around 5,800 plants, which was part of the chicken run.

Preparing a Comfrey Bed:

The comfrey bed should be in full sun. The plot needs to be meticulously forked over to remove any traces of nasty perenial weed roots, especially couch grass roots, convolvulous roots and oxalis bulbils, as you will never be able to get rid of them once the comfrey is established. Work over the bed clearing all the weed roots, and then leave the plot alone for a few weeks to allow the roots you have missed to sprout so as you can eliminate them as well.


Once you have made sure the plot is free of both nasty perenial and annual weeds, then you will need to feed the soil. It may seem strange that you need to feed a plant that in itself is going to be compost, but there is logic to this madness. You feed the comfrey with strong organic nitrogen fertiliser – fresh chicken, pig, fish or dried blood manure – and the resultant comfrey is an ideal perfectly balanced potash rich fertiliser for fruiting plants, shrubs and trees; in the same way as one uses small amounts of high Nitrogen manures in a compost heap to rot down a larger amount of high Carbon cellulose material to produce a well balanced finish product.

Comfrey will need feeding regularly at least once a year with a rich organic fertiliser, but it is also important to feed the soil well before planting the comfrey offsets. Fresh horse manure will inevitably have many weed seeds in it that will cause trouble, so I suggest incorporating two buckets of well rotted garden compost that reached at least 50oC during its composting to kill any weed seeds, plus one handful of blood and bone meal or fish meal (or 30g dried blood) per square metre; top dressing with the same every year in the spring. An alternative is one bucket of chicken manure, or two buckets of pig manure per square metre.


Plant your comfrey offsets at 60 cm apart in rows 60 cm apart. This will allow for optimum production as well as plenty of room for hoeing between the plants. When they are growing well you can mulch the bed down with a good layer of grass mowings, or spray-free straw to keep the annual weeds down and help to keep the soil moisture in.


You can expect to get four or five cuts a year. Cut before the plants go to flower. The method used to harvest your comfrey, depends on the scale of your plot. For gardeners, hand cutting, but for a horticultural setup, mechanical cutting will probably be more appropriate. I used to harvest our farm comfrey plot by hand, but only a section at a time, so there was a succession. I found the easiest way was wrap my left arm around the bunch of leaves and ‘saw’ off the leaves with a sickle, about 5 cm up from the ground, making sure not to cut off the growing points. The leaves were neatly left in the ajoining row ready to be gathered up later. A cautionary note: if you are going to cut a lot of plants it is worth noting that comfrey leaves have silica hairs that can graze the skin, so I advise wearing long sleaves and gardening gloves.

How to Use The Leaves:

Potatoes: You can either dig a trench 15 cm deep, lining the bottom with 1 kg of wilted comfrey for every 60 cm of row, scattering some soil on top, then set the potato seeds on top and cover with soil. Or, you can hoe or dig out a shallow depression and set the potatoes out then cover them with 1 kg of wilted leaves, then adding about 30 cm of spray-free straw later, when the potatoes are up for a no-dig solution.

Tomatoes: Mulch round the tomato plants with comfrey leaves. Also water the plants with liquid comfrey manure, every week through the fruiting period – see below.

Soft Fruit (Raspberries, Boysenberries, Blackberries, Currants, Blue Berries etc): Mulch around plants and liquid feed as for tomatoes.

Pumkins, Squash, Zucchini, Cucumbers etc: Dig in wilted leaves before planting, and much and liquid feed as for tomatoes.

Liquid Comfrey Manure:

You can convert a water barrel, or buy a similar sized barrel.

  1. Cut the top off to use as a lid. Drill a hole on the side near the bottom to fit a plastic tap which can be glued in place using ‘Gorilla’ glue. To stop gunk blocking the back of the tap, place some woven sacking over the hole and top up the bottom of the tank with course gravel to just above the tap.
  2. Prop the barrel up on blocks or bricks high enough to fit a bucket underneath the tap.
  3. We use several types of liquid manures, including comfrey. However all the others have water added to make them. Comfrey, on the other hand, does not need added water because comfrey is so low in cellulose that it will rot down on its own into a highly concentrated black liquid, which will keep well and smell a lot less than if water is added to the comfrey leaves.
  4. With the first loading of comfrey, moisten with a little water to start the rotting process. When adding further comfrey leaves, draw off half a bucket of comfrey juice and add that to the new load to speed up the rotting.
  5. Water down the liquid manure to a rich tea colour and water on or around your plants, especially when they are starting to set fruit. Repeat at weekly intervals throughout the fruiting season.

Comfrey in the Compost Heap:

Because comfrey is low in carbon it is not suitable for making compost on its own. Indeed there is no point, because it is already at 9 to 1 carbon/nitrogen ratio similar to well rotted compost, so it can be used as it is without composting. However, it is valuable to use it in building your compost heap along with other materials. The beneficial micro-organisms that break down organic material love comfrey almost as much as seaweed in a compost heap, and like seaweed, comfrey has lots of essential trace elements and other minerals which benefit both the micro-organisms and the quality of the final compost.

It is particularly valuable to add to a heap when one has a lot of high cellulose woody material like green prunings, cabbage and sweet corn stems and other end of season material like bean vines. Mixing the comfrey leaves in with the courser material will help to rot it down.

When building a compost in layers as described in the section on ‘HOW TO BUILD FERTILITY’ – ‘How to Make Great Compost’, one can add comfrey leaves to both the Nitrogen rich layers and the Carbon rich layers; just remembering that comfrey is low in cellulose and high in water, so it is best mixed with the dryer woody material such as straw as a balance.

Medicinal Uses:

Comfrey roots and leaves contain the small organic molecule allantoin, a substance that stimulates new cell growth, along with other substances that reduce inflammation. It was traditionally called Knitbone because it was used to speed up the regrowth of broken bones.

Externally: Comfrey ointment helps to heal bruises as well as pulled muscles and ligaments, fractures, sprains, strains, and osteoarthritis, as well as speeding up the regrowth of cuts and burns. One of our cows had ripped skin off one of her teets which we applied comfrey ointment to on a daily basis until the skin had regrown. I often use comfrey ointment on cuts to speed uo regrowth. Comfrey is both vulnerary and astringent, which means it protects against infection and stimulates new cell growth.

Internally: Comfrey contains hepatotoxic pyrrolizidine alkaloids which can damage the liver if taken internally on a regular basis. Personally, I have taken comfrey internally along with other herbs along with my usual conventional medicine to help with my inflamatory bowl disease when I had bad bouts, but I only took it for a few days until the symptoms settled down. If I had a broken limb, or a stomach ulcer, I would take comfrey root infusion for a limited time with other healing herbs.

Removing Comfrey:

If you have to remove comfrey plants, then just digging up the plants will inevitably leave some broken roots in, each of which will grow. So if you want to move plants to a new location, or get rid of them altogether, you will need to chop the plants off about 5 cm below ground and replant this portion, cutting it up into ‘offsets’, each with a root and a growing point ready for replanting elswhere, unless you want to dispose of them.

Then spread sodium chlorate weed killer on the white surface of the cut roots, enough to cover the root thinly. This will penetrate the roots killing them off the plants completely. A safer way to kill the roots is to use ammonium sulphamate, which brakes down into ammonium sulphate fertiliser. It should be spread on the roots in the same way as sodium chlorate.


Comfrey is a valuable resourse for any gardener, horticulturist or farmer who wants to be organic, biological and/or sustainable. Growing and using comfrey, along with all the other sustainable practices discussed, should be a natural part of the process of creating healthy, vibrant living soils and nutrient dense food.



Although well rotted humus rich organic matter is essential for thriving vital soil life, it is also important to supply regular fresh organic plant material. For this we need green manures. Bare soil is an anathema to anyone growing food sustainably (and indeed in nature), nutrients wash out when it rains, and ultraviolet light and wind can desiccate and kill soil life. One answer is to cover the soil with a green manure between growing crops. Green manures are a crop of plants grown solely to dig in or apply to the surface of the soil to give the soil life some fresh organic material to work on. When green manures are incorporated or added to the surface layers, there is a huge increase in biological activity in the soil.

The Benefits:

Green manures hold nutrients in their leaves, roots and stems, which stops the nutrients being washed out of the top soil, especially during winter.

  • When the plants die, they return nutrients and organic matter to the soil to feed soil bacteria and useful fungi, which will release food for the next lot of plants.
  • During the breakdown of organic matter by micro-organisms, compounds are formed that are resistant to decomposition, such as gums, waxes, and resins.
  • These compounds, plus fungus threads (mycelia), mucus, and slime produced by the micro-organisms, help bind soil particles together into granules, called aggregates. A well-aggregated soil is easy to work, is well aerated, and holds water better
  • Legume (pea & bean family) green manures also capture nitrogen (an important plant food) from the air & hold this in their root nodules
  • Some green manures help to control diseases. Others attract beneficial insects to your garden, which help to control pests

There will be periods of the year, especially in the winter, when there will be gaps in cropping and this is just the time when green manures should be grown. Green manures also stop the leaching of plant nutrients during wet periods.

Which Green Manures to Grow?

It is important to know what crops will follow your green manure. For instance, if you are going to grow peas and beans next season, a good winter green manure would be oats or mixed grain. The Nitrogen root nodules on the following peas and beans will be stimulated by the dug in grain carbon crop and help to rot the grain down. On the other hand if there is going to be a brassica crop next season, a winter crop of lupins, vetch or crimson clover, or a mix of them will provide nitrogen for the hungry brasicas planted in spring and early summer.

Here is a list of green manure crops, their particular values and their place in the rotation system. The legumes will add nitrogen and some will help control pests and diseases as well.

Blue Lupin (Lupinus angustifolius)

  • Adds nitrogen to the soil from its root nodules
  • Winter hardy
  • Vigorous grower that produces a mass of green matter
  • Breaks down quickly when chopped prior to flowering
  • Good before potatoes, sweet corn, brasicas and other Nitrogen hungry crops
  • 1 handful per square metre (30g per sq M) – sow in drills, or chop in with rake

Buckwheat (Fagopyrum esculentum)

  • Fast growth
  • Excellent beneficial insect attractant
  • Frost sensitive
  • Good quick crop between late summer crops and autumn planted crops – e.g. between spring and summer brasicas and June sown garlic
  • Sow 1 handful per square metre (25g per sq M) late spring & summer – sow in drills, or chop in with rake

Crimson Clover (Trifolium incarnatum)

  • Adds nitrogen to the soil from its root nodules
  • Winter hardy
  • Excellent beneficial insect attractant
  • Annual clover
  • Good before potatoes, sweet corn, brasicas and other Nitrogen hungry crops
  • Sprinkle 1 handful per 2 square metres and lightly rake in to cover, or 2.5g per sq metre

Lucerne (Alfalfa) (Medicago sativa)

  • Adds nitrogen to the soil from its root nodules
  • Winter hardy
  • Establishes easily and is perfect for rejuvenating worn out soils
  • Breaks up soil pans with its vigorous roots and draws up sub-surface minerals
  • Drought resistant
  • Good for growing through winter before Nitrogen hungry crops
  • Good for breaking in new land. Keep cutting for a season, and then turn in
  • 1 handful per 4 square metres and lightly rake in or cover with 1cm crumble compost

Marigold (Tagetes patula)

  • Use as part of a rotation
  • The marigold root exudes ozone which encourages all nematodes in the root zone to mature without reproducing
  • Grow as a companion crop with tomatoes and around kiwi vine roots
  • Sprinkle 1 gram on 2 square metres and lightly rake in

Mustard (Brassica alba)

  • Excellent for weed seed control
  • Very fast growing and prefers most soils
  • Cleans up some harmful soil fungi
  • Helps control potato eelworm and verticillium wilt
  • Grow before or after potatoes
  • Sprinkle 1 small handful per square metre, aiming to sow the seeds at approximately 25mm apart, and then rake over again to cover the seeds

Oats, Wheat, Barley (individually or mixed)

  • Provides lots of organic matter
  • Predator insects love it
  • Winter hardy
  • Suitable for all soil types
  • Prevents soil erosion
  • Good winter crop before peas and beans
  • Sow 2 handfuls per square metre, in spring or autumn – sow in drills, or chop in with rake

Phacelia (Phacelia tanacetifolia)

  • Quick growing
  • Excellent beneficial insect attractant
  • Good for early spring growth, before late crops
  • Sow from September – April. Sow one handful per 4 square metres and rake in

Tick Beans (a form of small broad bean) (Vicia faba)

  • Adds nitrogen to the soil from its root nodules
  • Winter hardy
  • Good to sow with oats, wheat, or mixed grain
  • Good before potatoes, sweet corn, brasicas and other Nitrogen hungry crops
  • Sow at around 50mm spacing. Push 20mm into soil, or sow in drills 50mm apart

Vetch (Vicia villosa)

  • Adds nitrogen to the soil from its root nodules
  • Winter hardy
  • Good mixed with oats, or mixed grain
  • Good before potatoes, sweet corn, brasicas and other Nitrogen hungry crops
  • Sow seeds 7cm apart in drills 10cm apart – or one handful per square metre and rake in

How to Plant and Dig in a Green Manure Crop 


  • Clear the soil of the remains of the previous crop and clear weeds
  • Rake level
  • Scatter fine seeds (mustard, vetch, phacelia, oats etc, crimson clover, Tagetes) at the rate instructed on the packet
  • Rake in
  • Water
  • Cover with fine netting against birds
  • Sow larger seeds (lupins, buckwheat, oats etc) in seed drills (1-2cm deep) drawn out with the corner of a hoe, or the side of your hand, at the rate instructed on the packet
  • Rake the soil over seeds
  • Water
  • Cover with fine netting against birds

Incorporating into the soil:

  1. Before the plants flower, cut down with a spade at the base, or chop with a Bombayhoe. Chop before flowering while there is still a reasonable amount of protein in the plants to provide nitrogen for the next crop.
  2. Leave a couple of days to wilt
  3. Scrape back the green manure to expose a 30cm wide strip at one end of the bed
  4. Dig a shallow trench (about 10cm deep)
  5. Scrape some green manure into it
  6. Dig trench next to the first, filling the first trench
  7. Continue up the bed
  8. Leave to rot down for a minimum of 2 weeks before replanting

If you want to, you can fork the bottom of each trench, by pressing the fork in with your foot and levering the subsoil lose, every 8cm or so. This will improve aeration, especially on a heavy to medium soil.

To help the green manure to rot, water on liquid EM plus an equal amount of dissolved molasses on the chopped plants in the trenches as you go, or on to the chopped crop before incorporating it into the soil.

For no-dig practioners – sow seeds as above. Seeds can be covered with a fine coat of well rotted crumbly compost, or a light sprinkling of untreated or organic straw.

When ready, pull or cut the crop and leave to wilt on the surface for a couple of days; then cover with untreated or organic straw, or grass mowings to rot down.


Generally speaking, given a healthy soil life and balanced nutrients (see section on Ideal Soil Mineral Balance) it should not be necessary to use high Nitrogen liquid manures on a regular basis. However, they do have an important role to play in plant nutrition when use intelligently. There are also other types of liquid manures that can supply high levels of potassium and/or a wide range of essential trace elements. Here is a list of the most common:

Animal manures

  • Stinging nettle
  • Comfrey
  • Seaweed
  • Nasty weed roots
  • Compost Tea
  • Lucerne hay Tea

Liquid animal manures provide a valuable Nitrogen boost plus Calcium, along with many other nutrients. For most crops growing in a healthy balanced soil the natural supply of Nitrogen will be available, but there are times and particular types of crops that will benefit from liquid animal manures. The heavy feeders such as Maize, Sweet Corn and the Alliums (onions, leeks, garlic) will benefit greatly from a Nitrogen boost once or twice during the growing season. Place the manure in a woven bag and hang by string or cord in a barrel of water. Water down to around 9 parts water to 1 part liquid manure, or until it looks like week tea.

Stinging Nettle provides Nitrogen and Iron and a general tonic if fresh. Fill a barrel of water 2 thirds full of nettles – as a tonic use within a few days. As a general fertiliser leave until it smells like manure. Water down 9 to 1 and water plants and soil.

Comfrey Liquid is a great high Potassium feed which is ideal for fruiting plants such as squash, pumpkins, peas, beans, tomatoes, peppers, egg plants, and of course all fruit (with the exception of citrus fruit which prefer a high Nitrogen feed).

The biggest mistake is to make comfrey liquid by adding comfrey leaves to water. Comfrey is very low in cellulous and as a result will rot down without water, resulting in a very dark and not very smelly liquid that will keep for many months. It needs watering down about 40 parts water to 1 part comfrey liquid, or until it looks like week tea.

Seaweed Liquid

Seaweed is not a general fertilizer being low in Nitrogen and Phosphorus – however it is a valuable source of Potassium which promotes flowering and fruiting, but more importantly it contains almost all essential trace elements known to man. Plants need trace elements to thrive – so when you water or spray the liquid on your plants they benefit – and when you eat them or their produce, you get all the trace elements as well!

Soils in many parts of the world, such as here in New Zealand are naturally short of some essencial trace elements such as Iodine and Selenium, both of which are abundantly found in seaweed in a fully chelated (immediately available) form.

Seaweed also contains a healthy dose of natural plant hormones which stimulate plant and root growth. It contains alginates which improve soil structure and is also loaded with carbohydrates which encourage large populations of beneficial micro-organisms in the soil. Seaweed is also an excellent food source for beneficial fungi in the soil such as micchorizae.

It is particularly beneficial for tomatoes, peppers, egg plants, squash, potatoes, fruit bushes, strawberries, peas and beans. In fact it is useful for all plants, and if there is a complete range of essential trace elements in the soil and the plant, then we get them in our diet.

Water the soil around plants, or water or spray on the leaves as a foliar feed every 2 weeks to help them resistant to pests and diseases. Liquid seaweed has mild fungicidal properties and helps to deter pests. You can also water onto layers in your compost heap as an activator.

Collect seaweed from the beach and half fill your tub, then top up with water and start to use after two weeks. To use: add 1 litre of liquid seaweed to 5 litres of water.

If you don’t live near the sea, you can buy liquid seaweed concentrate from the gardeneing section of many stores. Also dried seaweed powder (or meal) can be found in stores or on line.

Nasty Weed Root Liquid

The roots of convolvulus roots, couch grass roots, oxalis corms, dock roots, dandelion roots, etc, are hazardous if added to a compost heap, because they will most likely not rot and you will spread then around your property when you apply your compost.

However they contain many valuable plant nutrients, which should be recycled; couch grass for instance is high in Phosphorous. One good way is to drown them in a tub of water, preferably with a tap on the bottom. After a minimum of 6-12 months the resultant liquid can be added to the compost heap as you make it; or the juice can be used as a liquid feed (1Ltr of liquid weeds to 5Ltr water) and when you are sure the weeds are dead, they can also be added to a compost heap.

If the liquid manures start to smell this is a sign you are losing valuable plant nutrients. To control this and improve the effectiveness of the final product, add EM (Essential Micro-organisms) liquid plus an equal amount of molasses – see below.

Compost Tea

Making compost tea is more complicated than most other organic liquid fertilisers, but it is well worth doing on a regular basis. Compost tea is not just a rich brew full of plant nutrients; it is also full of beneficial micro-organisms. When sprayed on the leaves and stems its huge number of beneficial micro-organisms consume and out-compete disease-causing organisms for plant surfaces and food resources. They also occupy the space around infection sites so even if the disease-causing organisms do start to grow, they can’t penetrate into the tissues of the plant.

When added to the soil it feeds and increases the beneficial micro-organisms already there and also adds a lot more. It is a great addition to adding compost to the soil, because you are putting it directly on the plant’s leaves and stems as a feed as well as disease control.

What are the benefits of Compost Tea?

  • Tea-applied microbes consume and out-compete pathogens for plant surfaces and food resources
  • Reduces application rates of chemical pesticides, herbicides, and fertilizers.
  • Increases the number of organisms on and around the plant to compete with disease-causing organisms.
  • Occupies the space around the infection sites so even if the disease-causing organisms do start to grow, they can’t penetrate into the tissues of the plant.
  • High nutritional value for plants and soil
  • Provides food to:
    1. Feed beneficial organisms that protect plants (occupies infection sites)
    2. Sustain and inoculate plants
    3. Help extend root systems
    4. Add nutrients (biology) to the soil
  • Increases water and nutrient retention
  • Increases microbial numbers and activities
  • Aids in the breakdown of toxins in the soil and on plants
  • Helps our watershed soil and water quality by improving soil structure, which in turn increases water infiltration/retention, oxygen diffusion, and microbial activity
  • Enhances organic taste of fruits and vegetables
  • Creates a safer place for people and animals by using a natural approach to plant and soil health rather than using chemicals
  • Impossible to over apply to plants and soil because it is completely natural and organic
  • Since you are able to spray the tea directly on the leaves of the plants, this puts the organisms directly on the plant as opposed to adding compost to the soil around the plant.
  • Portability-You can spray at a rate of approximately 5.5 ml per square metre (56 litres per hectare), depending on the biological numbers of your tea solution and 22.5 ml per square metre (224 litres per hectare) on soil drenches.

To make compost tea you will need:

  • An aquarium pump
  • Several feet of tubing
  • An aquarium airstone bubbler
  • A stick to stir the mixture
  • Unsulphured molasses (preferably organic)
  • Something to strain the tea, like an old pillowcase, tea towel, or a nylon stocking
  • A bucket (20 litres is best)

Don’t try to make compost tea without the aeration equipment. If the tea is not aerated constantly, the organisms in it will quickly use up the oxygen and the tea will start to stink and become anaerobic. An anaerobic tea can harm your plants.

It is best to use collected rain water, but if you can only use city water, run the bubblers in it for about an hour first, to blow off any chlorine, otherwise, the chlorine will kill all those beneficial organisms you’ve gone to the trouble of raising.

Fill the empty bucket a third full of compost. Don’t pack it in; the airstone bubbler needs loose compost to aerate properly.

When it’s going, add a tablespoon of molasses, then stir vigorously with the stick. The molasses feeds the bacteria already in the compost and gets the beneficial species growing really well. After stirring, you’ll need to rearrange the bubbler so it’s on the bottom and well spaced. Try to stir the tea at least a few times a day. A vigorous mixing with the stick shakes more organisms loose and into the tea. Every time you stir, be sure to reposition the bubbler.

After 24 hours, turn off the pump and remove the equipment. If you leave the tea aerating longer than three days, you must add more molasses or the good organisms will start to become inactive because they don’t have enough food. Let the brew sit until the compost is pretty much settled out, 10 to 20 minutes, then strain it into the other bucket or directly into your sprayer. This is the time to add liquid seaweed for trace elements if you want to. Use the undiluted tea right away, within the hour if possible.

You can put the solids back on the compost pile or add them to the soil. There are plenty of good bacterial and fungal foods left in them.

Lucerne Hay Tea

For some reason beneficial soil protozoa live on and love lucerne. A healthy population of protozoa in your soil are important for releasing Nitrogen for plants to feed on and are an important food for earthworms. To increase the populations of protozoa in your soil, apply lucerne tea.

Lucerne tea is made in the same as compost tea, only using spray free, or organically grown, lucerne hay at 70 grams of hay to 2 litres of rain water. Use the fish tank airstone aerator as for compost tea for 24 hours then water onto the soil.


One problem when growing food and fruit trees and bushes and nuts, and indeed the bi-products of forestry, is that you end up with a lot of woody material which is difficult to cope with. You can use a shredder, but this uses a lot of fossil fuel. The best way to process woody material is to make charcoal and help to sequester carbon and take it out of the atmosphere, as well as improving the soil.

The use of ground charcoal added to soils has been used as a technique by various groups of traditional societies, like the Maoris and some African tribes, but it was a rediscovery of an extinct civilisation, wiped out by European diseases in the sixteenth century that existed on the banks of the river Nigra in Brazil, that has excited interest in this technique. Amazonian rainforest can be considered as a ‘wet-desert’, because it grows on red and yellow clay-like laterite soils which are rich in aluminium oxide and iron oxide, but little else, with almost no ability to hold onto nutrients, but the peoples of the river Nigra discovered the use of ground charcoal as a way of creating a very fertile soil many centuries before the arrival of Europeans.

They used ground charcoal along with composted organic waste to create Terra Preta (black earth) which still contains up to 30 per cent black carbon and covers an area twice the size of New Zealand. It appears to play the same role as clay minerals that ‘hold onto nutrients until needed by the plants. The charcoal last for hundreds, possibly thousands of years, continuing to do its job. When viewed through an electron microscope the charcoal particles look like black coral, full of holes, which provides a huge surface area to both hold onto plant nutrients as well as provide a lot of space for micro-organisms. Overall populations of beneficial fungi and bacteria are high in terra preta soils.

However, it is important to be aware that using charcoal is not a substitute for humus. Charcoal is Carbon primarily, and in itself lifeless. Humus on the other hand has Carbon (10 parts) and Nitrogen (1 part) – as such it serves as a source of energy for the development of various groups of micro-organisms as it is constantly being formed from plant and animal residues and is continuously decomposed further by micro-organisms, which among other things make the Nitrogen available for plants.

The ancient peoples of the river Nigra used charcoal to create soil that had a high cation exchange capacity and with its porous structure provided a huge area for beneficial bacteria to live and thrive as well as good water holding and aeration capacity, but in studying the ancient sites, archaeologists analysing the Tera-Preta have found a lot of plant and composted remains mixed in the soil, which shows the ancients understood the importance of composting and recycling their food and other organic waste.

Having said all that, using ground charcoal it is a great way to re-vitalise soil fertility and help rescue infertile soils, or soils that have been damaged by modern conventional horticultural and farming techniques as well as increasing the exchange capacity of already healthy soils. One of the best ways to add ground charcoal to the soil is via the compost heap.

Perennial crops, such as shelter belt trees and many natives can be grown and trimmed or cut on a regular basis to use to make biochar. Indeed shelter belts around commercial orchards are regularly trimmed and could be used for this purpose.

To make biochar, pile up woody debris, along with dried leaves if you have them, in a shallow pit in your garden bed. Burn the brush until the smoke thins and then damp-down the fire by covering it with about 30mm of soil. Let it smoulder until the brush is charred, then put the fire out. On a larger scale, industrial scale plants can be built to burn woody material, making charcoal and gas or biofuel as a bi-product.

Whatever way we make biochar, we just need to remember that the vast majority of the bulk of all plants is made from carbon dioxide and sunlight and what we are doing is reversing the process of burning fossil fuels, which were originally made the same way. Burning fossil fuels increases carbon dioxide in the atmosphere. Making biochar and compost and adding it to our soils will reverse the huge damage we have been doing to our soils over the last century in particular and help to reverse climate change at the same time. If adopted world wide these two techniques alone would have a huge effect; not only sequestering carbon but helping to revitalise soils denuded by modern farming techniques.


One rarely sees bare soils in nature. There is a covering of growth and/ or a natural mulch of decaying leaves and other dead plant material, as on a forest floor. So to replicate this in a horticultural setting, apply mulches of plant materials.

It is important to consider the best and most natural type of mulch to use for each crop. For instance: the most natural mulch for bushes, fruit and nut trees would be homemade leafmould (see section: LEAFMOULD PRODUCTION above) or possibly wood chips. On the other hand plants that prefer good Nitrogen availability, such as sweet corn, the onion family and the brassicas, will benefit from high nitrogen mulches such as grass mowings or chopped up young legume green manure, maybe topped with coarser material. Large upright crops can cope with deeper mulches, whereas fine grass mowings are better for small delicate young crops like carrots. Using hay, cereal straw or pea straw around carrots or other young seedlings will just smother them.

Mulching Benefits:

  • Will help to protect the top layer of soil from the drying effects of the wind and the searing of ultraviolet rays.
  • Helps to conserve moisture and cut down on water use.
  • Helps to control annual weed growth
  • Regular mulching helps to improve soil texture, by allowing worms to work in the surface layers and protect against capping caused by heavy rain.
  • Reduces water erosion.
  • Moderates extremes of soil temperature, keeping the soil cooler in summer and warmer in winter.
  • Encourages an increase in beneficial soil micro-organisms, and larger organisms – most importantly earthworms.
  • Provides some nutrients and eventually humus as the mulch decays.

Mulching is very effective against annual weeds, it is not perfect, but it greatly cuts down the task of weeding. However it is not a panacea for perennial and nasty weeds, but it will definitely cut down the work load of weeding out annual weeds – so if you have persistent perennial weeds like couch grass roots, convolvulus roots, oxalis bulbils, etc, they will need digging out and dealing with before laying down the mulch (see: section Nasty Weed Root Liquid in the Liquid Manure section above).

Often when growing crops, especially large plants like sweet corn, potatoes, tomatoes, broccoli, Brussels sprouts, fruit bushes etc, there will be a lot of bare soil around them; this is the occasion to cover the soil with a layer of spray free straw, old seed free hay, or grass mowings. One can also grow green manure crops for cutting and using as mulch. For smaller plants, such as young carrots, use grass mowings or leaf mould and for large fruit trees, wood or bark chips, but better still use home made leaf mould which is the most natural mulch for trees and bushes.

A warning! There is evidence that applying very thick mulches continuously over time, which is not replicated in nature, smothers soil life and eventually results in excessively high levels of potassium. The best approach is to use mulches judiciously and not too thick for too long. Also when clearing crops or the remains of crops, this is a good time to clear away old mulches to add to compost heaps, leaving the soil exposed for some time before sowing and planting the next crop. Never spread mulch on a dry soil as it will keep it dry, which is the opposite of our purpose. Always spread it after rain or water thoroughly before applying.

Types of Mulches:

  • Cereal Straw is cheap and more available in rural areas. Only buy straw guaranteed spray-free or organically grown!
  • Pea Straw is more available in rural areas. Only buy straw guaranteed spray-free or organically grown! Higher in nitrogen than cereal straw
  • Lucerne Hay is more available in rural areas. Only buy straw guaranteed spray-free or organically grown! Higher in nitrogen than cereal straw
  • Cut Green Manure – Use your own. Usually green manures are  chopped or dug in where they grow, but you can cut them to use as mulch elsewhere and still dig in the roots
  • Leaves – Collect for free. Collect only from under deciduous trees. Better added wet to stop them blowing away in the wind. Conifer and eucalypt leaves have toxins which can harm some plants and are usually acidic
  • Sawdust is cheap. Collect from Sawmills or cabinet makers. It is essential that it is from untreated wood! Only use around trees and perennial shrubs. Medium lasting, several years to decompose
  • Wood Chips are often available from rural areas or from local contractors. Again, be sure they are from untreated wood. Long lasting. Only use around trees and perennial shrubs
  • Shreddings – If you have a garden shredder or can get hold of shreddings locally this makes great mulch, as long as it doesn’t have nasty persistent weeds in it.
  • Lawn Mowings are best used fresh. If you use someone else’s, make sure the grass has not been sprayed with hormone weed killer. Decomposes fast. Best used only 1 or 2 cm thick, because it will heat up causing damage to plants if too thick
  • Garden Compost – Use only your own. The life in the compost will die out if left on the surface exposed, so cover with other mulch.
  • Seaweed – Collect from beaches especially after storms. Wash to remove salt. A good mulch which is full of trace elements – good for plants and those that eat them
  • Horse Manure – Cheap to buy. Good mulch, supplies nutrients. Often full of grass seeds from the hay the horses ate. As for garden compost, best to cover with other mulch such as straw. Some of the nitrogen in the manure will be lost. Better used as an activator when making compost
  • News Paper – Readily available. Particularly useful under shrubs, trees and other perennial crops. Do not use coloured news print as this contains heavy metals. Soak papers first and lay several layers, then top with wood chips, composted pine bark, or leaves
  • Mushroom Compost – Locally available, often sold in garden stores or departments. Intensive conventional mushroom farming uses many nasty chemicals to control diseases and pests, so only use mushroom compost from organic mushroom farms. It will usually be well rotted horse manure. A good mulch that will probably produce some mushrooms the first year
  • Pine Bark – Readily available. Make sure it has been well composted to neutralize natural toxins. Only use around shrubs, trees and other perennials

You will notice I have not included black plastic, because it does not allow the soil to breathe and there will be a build up of toxins underneath becoming smelly making the soil inactive. It does not let in the rain. Plants can become to dry and hot under plastic. I do not recommend it! However, woven weed mat is good for paths covered in bark, or stone chips, but I would not use it where plants of trees are growing.



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