Compost – bins and tips

Compost Bins

Compost can be made in a variety of containers. The examples below show a double bin made from recycled timber, a double bin made from recycled, heavy gauge bird wire covered with knitted polypropylene shadecloth, and a commercial single bin. Double or triple bins are best as you can turn the compost from one bin into the next, with the third bin used to start a new heap.
dblcompost compostbins2
Compost tumblers (below, right) do the work of aerating the mixture. They are suitable for composting small quantities of fairly soft ingredients quickly, for people who are not able to turn compost easily, but the mixture may not generate enough heat to kill diseases.
SAMSUNG DIGIMAX A503 SAMSUNG DIGIMAX A503
Homemade containers don’t require skilled carpentry. What goes into the compost container is more important than how it looks. The main points to remember in deciding on the size and site of your compost container are:

  • When ingredients form one cubic metre (i.e. 1 m. x 1 m. x 1 m.), aerobic bacteria will generate enough heat to kill diseases and weed seeds.
  • Open-base bins that are in contact with soil allow earthworms to enter the mixture (when it has cooled down) and provide worm castings to the mixture while they help complete the composting process.
  • Recommendations to position compost bins in full sun do not apply to many parts of Australia, as too much heat can kill off composting organisms. A shaded spot is ideal.
  • Compost bins need a cover to prevent the ingredients becoming sodden in heavy rain.

Some Composting Tips

If you are new to compost making, don’t be intimidated by statements of the ratio of carbon to nitrogen in compost making. Most recommended ingredients contain a mixture of both. With a little practice, you will quickly learn to identify and correct any imbalances.

  • Chop up tough items using shears, a shredder, or a sharp spade (spread items on soil or grass first to prevent jolting). This assists faster decomposition as bacteria work on the surfaces of organic waste. The more surfaces you can provide – the faster they can work.
  • The secret to making compost quickly to turn it regularly to keep it aerated, and to keep it damp as aerobic bacteria that commence the process require nitrogen, air and moisture to process the carbon.
  • The secret to fast composting is regular turning and mixing of the ingredients. Weekly turning while the ingredients are generating heat will produce mature compost very quickly. As the compost breaks down, the mass is reduced.
  • You don’t have to wait until you have a cubic metre of ingredients – turning and mixing ingredients will get the bacteria working.
  • If the pile looks grey or contains ants – it is too dry. Turn and mix the ingredients, while adding enough water to dampen the mixture.
  • Don’t be concerned about slaters in your compost heap. They feed on semi-decomposed organic matter.
  • If the pile is black with an unpleasant smell – it is over-wet. Air has been forced out, and anaerobic composting has begun. Turn and mix the ingredients, while dusting with agricultural lime every 15 cm, and adding some straw to the mix. Protect pile from rain.
  • If the pile seems inactive – it may need more nitrogen. Turn and mix the ingredients, while adding some manure every 20 cm. If manures are unavailable, you can substitute a generous sprinkling of poultry-based, organic-allowed fertiliser.
  • Your compost is ready when it is dark brown, crumbly, with a pleasant earthy smell and ingredients, apart from pieces of egg shell, are no longer recognisable. A 5 cm layer added to topsoil provides your garden with all the minerals that plants, animals and humans need for good health.

Compost materials

OLYMPUS DIGITAL CAMERA Compost is made by combining organic waste than provides nitrogen and/or carbon. The advice to make compost from waste that is green (provides nitrogen) and brown (provides carbon) is a bit confusing when manure contains a lot of nitrogen, but most of it is brown. When suitable dampened materials are combined in a heap that has contact with the soil, heat is generated and millions of aerobic bacteria get to work transforming the fuel into a compost-making factory.

Good Fuels

  • Manure from animals that eat grass (lots of nitrogen)
  • Chicken manure (lots of nitrogen)
  • Weeds without seed heads (nitrogen and carbon)
  • Lawn cuttings that have wilted (nitrogen and carbon)
  • Green prunings – shredded (nitrogen and carbon)
  • Raw vegetables and fruit – chopped for fast break down (nitrogen and carbon)
  • Uncooked kitchen waste – including tea bags and coffee grounds (nitrogen and carbon)
  • Old plants – chopped for fast break down (nitrogen and carbon)
  • Bedding straw for animals that eat grass or seeds (lots of nitrogen and carbon)
  • Straw and hay (lots of carbon)
  • Cardboard boxes and egg cartons – shredded (carbon)
  • Undyed wool, feathers and hair (nitrogen and carbon)

In Small Amounts

  • Newspaper and waste paper – separate sheets crumpled or roughly shredded (carbon)
  • Woody prunings – shredded (carbon)
  • Wood shavings – (very slow to break down and tie up a lot of nitrogen)
  • Seaweed – well-washed (helps factory work faster)
  • Herbs – comfrey, yarrow and chamomile (help factory work faster)
  • Egg shells – crumbled (keep compost smelling sweet and earthy)

Do Not Add

  • Plastic or foil containers, wrapping or disposable nappies
  • Fruit or vegetables that have been attacked by fruit fly or codling moth (larvae can pupate in factory)
  • Plants with diseases
  • Cat, dog or human faeces* (these can spread diseases through compost)
  • Rats or mice* (can spread diseases through compost)
  • Grey water (upsets pH balance and slows process)
  • Soil – makes compost heavy and harder to turn (amount clinging to weed roots is sufficient)
  • Earthworms – the initial heat will kill them. Earthworms know when to move into a compost factory.
  • Synthetic fertilisers (delays process and deters earthworms)

If you only have small quantities of organic waste to recycle, a worm farm would be a better solution. See Compost Worm Farm.
For information on how compost makes garden soil healthy, see Compost.
** Cat and dog faeces, and vermin, can be composted anaerobically in a small pit or container, but this compost should not be added to garden beds.

Compost

compostbins2 Composting recycles organic waste into a product that makes garden soil healthy. Mature compost is a dark brown, sweet-smelling material that can be added to topsoil.
There are two ways to make compost – aerobic, which requires aeration during the process, and anaerobic, which is a slow, rather smelly process. Mature aerobic compost can be produced in about 6–8 weeks in most areas of Australia.

How does compost make garden soil healthy?

  • Compost keeps soil more moisture-retentive, yet better-drained.
  • Compost provides food for earthworms that increase the depth of fertile topsoil by leaving digested food along their deep tunnels.
  • Compost provides food and a home for the many helpful bacteria and fungi that help protect soil from soil-borne diseases.
  • Well made compost has a pH of 6.5 – where all plant nutrients are fully available, and the perfect pH for the majority of plants.
  • Compost buffers plant roots from an unsuitable pH in surrounding soil.
  • It also insulates plant roots from temperature extremes so that soil stays cooler in summer and warmer in winter.
  • Compost contains all the minerals that plants, animals and humans need for good health, most of the soil’s nitrogen, plus lots of humus that forms the most stable part of recycled organic waste.
  • Humus and the minerals that plants need both carry a weak electrical charge. The electric charge holds the plant food minerals close to plant roots and prevents them from washing away in heavy rain.
  • Humus is able to control the release of trace elements needed in tiny amounts, and block absorption of poisonous metals in soil so that they do not end up in our food.
  • Humus stores carbon in soil for very long periods of time.
  • Humus, in compost, provides a habitat for a soil community of billions of beneficial bacteria and fungi that perform important functions.
  • Some bacteria species in humus make a ‘glue’ that is able to hold soil particles in a way that improves the flow of water and air through soil. This improves the structure of soil so that plant roots grow more easily. Strong roots help plants to resist the effects of drought and storms.
  • Mycorrhiza fungi in humus stick like hairs to the roots of plants, helping them absorb water and nutrients in exchange for sugars produced by plants during photosynthesis. Some 95% of perennial plants rely on mycorrhiza for healthy growth.

Compost worm farms

compworms.jpg For organic gardeners who don’t have enough recyclable waste for a productive compost heap, a compost worm farm is the answer.

Compost worms are different from earthworms that tunnel through soil and move into compost heaps after organic matter has been partly processed by microorganisms. Consequently, the term ‘compost worms’ can be confusing to new gardeners. Worm farm (compost) worms require a moister and cooler environment than earthworms (10–30° C.), and feed on a wide range of organic matter, including vegetable and fruit waste (except for citrus and onions), wet paper and cardboard, grass clippings, aged cow and horse manure, soft weeds and hair. Chopping waste into small pieces provides a larger surface area for worms to feed on and speeds up production. The digested waste (worm castings) are a clay-like humus that contains all the nutrients and trace elements that plants need for good health in a form that plant roots can absorb immediately.

Worm castings are Nature’s slow-release, complete organic fertiliser. The more varied the worms’ diet, the better the fertiliser. Simply rake the worm castings into the topsoil on garden beds. As they do not smell, they are the perfect fertiliser for both indoor and outdoor pot plants. They are also a great addition to seedling mixes and, when diluted to very weak black tea strength, the liquid that drains from the worm farm is a fertiliser that gets seedlings off to a flying start.
Worm farming has become a very popular method of recycling and various commercial worm farms are available to suit different situations. Most children find worm farms fascinating and enjoy looking after them.

  • Commercial worm farms come with complete instructions, a starter colony of worms and edible bedding for the worms. Small commercial farms with several tiers are easily moved into a shed or garage in areas where frosts occur. Or, in frost-free areas, if you can find an old hip bath or large sink, you can make your own worm farm as we have here. Worm farming
  • Containers with a drainage hole prevent moisture build up in the base of the farm and a waterproof cover excludes light and rain. (Avoid using old carpet or underlay as a cover as these are impregnated with pesticides.)
  • Add a little water to the farm when necessary to keep the food and bedding damp.
  • A light dusting of dolomite every few weeks will keep the worm farm smelling sweet and the pH close to perfect.

HARVESTING WORM CASTINGS
Worms in farms with stacked trays will move up into the next highest layer when all the food in their tray has been eaten, and it is time to collect the worm castings.
Uncover the worm farm and leave the surface exposed for 15-20 minutes. The worms will move down through the castings away from the light. The castings will contain worm eggs. These are easily recognised as you can see in the photo. They are about the size of the head of a match, or a little bit smaller. Worms don’t lay their eggs in groups like some insects do. They lay them one at a time through the worm castings, but usually close to where they can find food when they hatch.
Harvestcastings1 Use a scoop to collect a layer of castings from the top of the farm. A scoop can be made from a 2 litre juice bottle with a handle. Spread the castings onto an old tray by lightly brushing the castings with gloved hands. Check for worm eggs and any small worms that might still be in the castings and put them safely back into the farm. Cover them with a layer of food.
Then tip the collected worm castings into a bucket and collect another scoop full of castings until you have enough to put into your garden bed, or to make ‘worm tea’.

Test compost pH before use

pHkit.jpg

It is wise to test the pH of compost (including homemade compost) before adding it to your topsoil because the pH of topsoil determines which nutrients are available to plants. Well-made aerobic compost has a pH of around 6.0 to 6.5. Unfortunately, I didn’t follow my own advice recently when, temporarily short of homemade compost, we purchased from our local Bunnings store some bags of Richgro ‘All Purpose Organic Compost’ registered as an allowed input by BFA.

I noticed that the transplanted seedlings where I had applied the compost were not making any growth although the rest of the vege patch was doing well. And, in the area where I had mixed extra compost through each planting hole, the seedlings had turned yellow – a clear sign that the soil pH was too high for the plants to absorb phosphorus for root growth, or iron. Iron (along with nitrogen and magnesium) is essential for chlorophyll (green colouring) formation in leaves that allows plants to produce carbohydrates for growth. Iron deficiency (iron chlorosis) starts in the tips of plants and the leaves of the whole plant turn yellow between the veins or, in extreme cases, white. In contrast, nitrogen chlorosis starts in the older leaves because, when nitrogen is in short supply, plants transfer the available nitrogen to the growing tips, and magnesium deficiency starts in the margins of older leaves.
I tested the topsoil of the affected areas and, finding it above 7.5, I then tested the Richgro compost and the reading was between 8.0 and 8.5. As the pH scale is expressed as negative logarithms, a reading of 8.0 means that the soil is ten times more alkaline than a neutral reading of 7.0. This week I received a question from a blog reader who is having difficulty reducing his soil pH. He had also used the same brand of compost, bought from Bunnings in WA.
Richgro’s response that their “internal records” of the batches in question show a pH of 7.1 and 7.2 and that the test kit I used “do not work well with high organic fraction soils or composts” blah, blah, is not consistent with the physical symptoms of the seedlings. I suspect the problem may have been caused by the type of timber used to produce biochar added to the product. Wood ash contains a very reactive form of calcium and, as the ‘Gardening with Biochar’ website states, Raising soil pH is biochar’s most important contribution to influencing soil quality.
* I must add that Bunnings were quite happy to accept return of the unopened bags of compost after I explained the problem.

To test pH
Add equal quantities of topsoil from the bed you are preparing and the compost you intend to use to a clean bucket. Mix thoroughly, then mix again. Test a sample of the mixture according to the instructions on your soil test kit. Ideally, for healthy growth of most plants, the pH reading should be between 6 and 7.2.
If soil pH is higher than this, please see: ‘Changing soil pH’
Also see: ‘What’s soil pH?’

Avoid digging near fruit trees

A reader has found that the soil around his fruit trees has become quite hard and has asked should he dig around the trees to loosen the soil.

It is not a good idea to dig around fruit trees as citrus, for example, have very shallow roots. Digging around these and stone fruit trees will damage roots and quite often cause suckers to grow from the root stock. Avocado trees deeply resent any root disturbance.

Hard soil can be a problem in extreme weather conditions, particularly if the soil has not been covered with mulch. If the area is weedy, cut off the weeds at ground level rather than pulling, or digging, them out. Plants obtain most of their energy for growth from light. As you are going to deprive them of light with this method, you can leave the roots to break down and add organic matter to the topsoil.
If grass has covered the area, cut it short and, with a sharp edged spade, cut through the runners 20 cm outside the ‘drip line’ of the tree, which is the area of soil directly below the outside edge of the foliage canopy of the tree – so called because it is where rain drips off the foliage canopy and the feeder roots of trees lie in this area.
Apply a light application of organic complete fertiliser to the soil surface in the drip line area and give the tree a thorough watering, but not close to the trunk. Immediately after watering, cover the soil surface beneath the tree out to the drip line with a 3 cm layer of compost, keeping the compost at least a hands width from the trunk. Compost contains microorganisms (and often earthworms) that will help break down the weed roots and make the soil more friable.
Then cover the compost with a 5 cm layer of organic mulch to keep compost damp and deter weed growth, keeping the mulch well clear of the trunk and extending it to 20 cm beyond the drip line of the tree. Don’t use compost as mulch, as it will dry out and you will lose most of its benefits.

Using wood ash

If you tend to accumulate wood ash from log fires over the colder months, you might be tempted to use it instead of lime to raise soil pH, as it contains between 45–50% calcium carbonate. It will certainly do that – but it should only be used on soils with a pH lower than 5.5 because the calcium in wood ash is in a highly soluble form that can change pH very quickly, and it is very easy to over-do the application. Ash from hardwoods contain one third more nutrients than ash from softwoods (e.g. pine).
Apply wood ash only to beds that are not going to be used for a while, using one handful per square metre. Test soil pH after 2 weeks to see if soil is in a more suitable pH range for plant growth. Wood ash should never be used near plants that prefer acid soils.
A safer way to use wood ash is to keep it in a covered container near your compost heap and dust it, instead of garden lime, between layers of other materials that you add to the compost heap. This will help to keep the compost heap sweet-smelling and ensure good microorganism activity. Mature compost holds nutrients in balance and compost containing wood ash can safely be applied to garden beds.
Wood ash can also be dusted over lawns that have become ‘sour’, especially where moss is growing. While the calcium improves the soil pH, the 2–8% potassium (potash) in wood ash will improve the lawn’s tolerance to heat and cold as well as improving disease resistant. However, if applying wood ash to lawns, avoid using seaweed fertiliser for the current season as seaweed also contains a considerable amount of potassium. Too much potassium can cause a magnesium deficiency.

Manure and mulch warning update

Last October I updated the warning about pyridine herbicides that can damage or kill both food crops and decorative plants. Unfortunately, some readers have since had plant damage after inadvertently purchasing manures or mulch that contain one of these herbicides, despite a NSW government website stating that no damage has occurred in Australia.
As a result, I am posting a reminder.
Pyridine herbicides are only effective on broad-leaf plants, but the chemicals remain active in mulch cut from sprayed pastures and in manure from animals that have grazed on sprayed pastures until the chemicals are broken down by soil microbes. Of particular concern to home gardeners and councils that recycle waste into compost for agricultural and domestic use are the products containing aminopyralid, clopyralid and picloram because they are quite persistent, and residue from these herbicides can damage plants for up to 24 months. However, because the Australian Pesticides and Veterinary Medicines Authority (APVMA) regards the person who sprays the herbicide as the ‘end user of the product’, any warnings are limited to product labels without any regard for unsuspecting gardeners who, in good faith, purchase mulch, compost or manures contaminated with the herbicide, and who may not recognise the cause of the damage to their crops because they have not personally used any herbicides.
A recent check of their website shows that the APVMA has registered 233 herbicides that contain at least one of the pyridine group of herbicides – an impossible list to check through before purchasing mulches, manures or compost. The entire tomato family, lettuces, sunflowers, spinach, strawberries and legumes are particularly susceptible to damage from these herbicides, which can also affect a range of ornamental plants.
To protect your garden from pyridine herbicide damage: only use aerobically composted manures on gardens. Aerobic composting requires weekly turning or stirring to ensure the composting process is carried out by microbes that require oxygen. Breakdown of the herbicide will be very slow in compost heaps that are not aerated.
Mulch that carries an organic-registered label does NOT contain any herbicides. Mulches from uncertified sources are high-risk products because the drying and baling of mulch materials eliminates microbial action, and the herbicide will still be active. The only safe compost to purchase is organic-registered compost.

If you are unable to purchase certified-organic manures or mulch, test the safety of the product by sowing some seasonally suitable peas or beans in pots containing certified-organic potting mix (with the manure mixed through it) or covered with the purchased mulch. (Water this pot through the mulch). Keep the test pots well-watered to eliminate other sources of stress. You should be able to see if an input is contaminated within 21-28 days. Dispose of any affected plants and potting mix with household garbage.
Symptoms to look for are:
Poor germination or death of seedlings, twisted, cupped or elongated leaves and twisted growth, misshapen pods.

Return remaining contaminated inputs to your supplier. If this is not an option, aerobic composting is the quickest way to break down these herbicides. Test the mature compost for herbicide residue.
If you find that the mulch has been affected, use it on beds that you can leave fallow until aerobic microbes in topsoil break down the herbicide or, if space is limited, compost it aerobically. if you find that garden beds have been affected, dig organic-registered compost through the bed and keep it damp to keep soil microorganisms breaking down the herbicide as quickly as possible.
Notify your supplier of the problem as pyridine herbicide product labels state that treated crops are not to be used for hay, silage or animal bedding, and manures are not to be spread on land used for growing susceptible crops.

Please also take a minute or two to notify the APVMA of problems with these herbicides. The APVMA encourage the public to report pesticide problems through their new Adverse Experience Reporting Program (AERP) by e-mail: aerp@apvma.gov.au, phone 1800 700 583, or fax: 612 6210 4813.

Further information:
Examples of pyridine herbicide damage

You can find Australian product names of these herbicides by going to the APVMA’s Public information (PUBCRIS) page. Under product type select ‘herbicide’, then type aminopyralid, clopyralid or picloram in the active constituent panel. Click ‘Search’.

The NSW Government has been aware of the problems with these herbicides in Australia since 2005: see  Organic

Soil pH is so important

I’ve had several e-mails recently from gardeners who have used purchased soil or organic fertilisers and found that their plants were sickly or not growing because they were growing in soil that is too alkaline.
Soil pH (acidity or alkalinity of soil) is extremely important because determines which nutrients are available to plants. All the major nutrients are only freely available to plants within a narrow soil pH range of 6.5 to 7.5, where essential trace elements are also available, and aluminium is locked out.
See What’s soil pH?

Lime should only be added to soil where testing of soil pH shows a need for it. Mushroom compost and poultry manure (including dynamic lifter) can be quite alkaline, and some suppliers are now adding lime to bagged cow manure and horse manure because some customers objected to the smell, (usually caused by nurseries leaving bags sitting in hot sun). And, only agricultural lime (calcium carbonate) should be used when liming is necessary as hydrated lime can burn plant roots and reduces nitrogen levels through conversion to ammonia.
When purchasing soil, always check the pH before adding fertilisers or lime to it, and always test the pH of your compost before adding it to the garden (well-made compost has a pH of around 6.0-6.5). If soil pH is not higher than 8, you can reduce the pH using elemental sulphur (according to the instructions on the pH kit) and dig into topsoil a 5cm layer of well-made compost, which will buffer plant roots from the unsuitable pH. Or, grow a legume as a green manure while waiting for the pH to reduce. Slash the legumes as they start to flower and dig them into the top 10 cm of soil. See Soil pH too high? , also Changing soil pH.

If the pH is higher than 8, it is not easy to reduce it with sulphur alone. As organic matter breaks down in soil it releases hydrogen ions that will replace the calcium ions in the soil, and gradually reduce the pH. Cow, horse or sheep manure (but not poultry manure) under mulch will also reduce the soil pH gradually as it breaks down. However, be very cautious where you source manures and mulch as more farmers are using herbicides that remain active in manures and mulch materials (except lucerne and pea straw) until they are broken down by soil bacteria. Test soil every 6 weeks after digging in the green manure, and you can use it for general vege growing when it gets below 7.5.

Herbicide damage

Broad-leaf weed killers that contain the pyridine herbicides have caused widespread damage to many gardens in New Zealand, the UK and the US in recent years, and these herbicides are now being sold in Australia.
Pyridine herbicides include aminopyralid, clopyralid, fluroxypyr, picloram, and triclopyr. They are only effective on broad-leaf plants, but the chemicals remain active in mulch cut from sprayed pastures and in manure from animals that have grazed on sprayed pastures until the chemicals are broken down by soil microbes. Of particular concern to home gardeners and councils that recycle waste into compost for agricultural and domestic use are the products containing aminopyralid, clopyralid and picloram because they are quite persistent in compost (particularly anaerobic compost), and residue from these herbicides can damage crops for up to 24 months.

Is it just me, or do other people think it is crazy that there is widespread concern about the future of food production in Australia, and all levels of government are advising us to recycle and store carbon, yet the Australian Pesticide and Veterinary Medicines Authority (APVMA) continues to register more and more of these herbicides that damage food crops, and little if anything is being done to warn the public of the risk in using mulches, composts or manures contaminated by these herbicides.
Although there are only two pyridine herbicides containing aminopyralid (Hotshot and Grazon Extra), the APVMA has registered 59 herbicides containing clopyralid, 54 containing picloram, 27 containing fluroxypyr, and 77 containing triclorpyr, and there are several more of these herbicides awaiting approval – an impossible list to remember when purchasing mulches, manures or compost.

The problem with Australian regulating authorities is that they regard the person who sprays the herbicide as the ‘end user of the product’ and any warnings are limited to product labels without any regard for the unsuspecting gardeners who, in good faith, purchase mulch, compost or manures contaminated with the herbicide, and who may not recognise the cause of the damage to their crops because they have not personally used any herbicides.

I am very grateful to Jo T. who has sent me a link to photos of damage to vegetable plants caused by aminopyralid. These may help readers identify this herbicide problem in their gardens.
http://www.geologywales.co.uk/storms/summer-2011-aminopyralid.htm

If you are unfortunate enough to have garden beds affected by these herbicides, click here for treatment information.
See also Herbicide warning.

Further Information:
You can find Australian product names of these herbicides by going to APVMA’s Public Chemical Registration Information System page. Select herbicide and then type aminopyralid, clopyralid or picloram in the active constituent panel.
The NSW Government has been aware of the problems with these herbicides in Australia since 2005:http://www.environment.nsw.gov.au/resources/warr/SPD_ORG_ReduceRiskHerbCompost_FS.pdf
Jo has also provided a link to UK information about aminopyralid problems.