Composting Manure

Animal manures have been composted for use in agriculture since the early days of farming using dung from whatever animals were being farmed. (Compost history)   Manure from a farmyard or animal pens will also include urine, which has a high nitrogen content, and the soiled carbon rich. bedding e.g. straw. Incorporating manure into the soil is an effective  way of replenishing the organic content  and creating humus. Adding manure, or  other humus rich  organic material such as garden compost to the soil increases the biodiversity, and nutrients  trace elements help improve the soil structure.  This is as important as  the provision  of N-P-K to the soil  but is often overlooked.

According to the Rodale Guide to Composting  (1979) manure was considered to be the most important single  ingredient in the compost heap,  and few heaps did not include at least a layer of manure. The use of manure has fallen out of fashion in home composting possibly as the emphasis of domestic composting has moved from converting  garden waste, from a large garden or allotment, into produce a soil enhancer  to composting household,  kitchen and waste from much smaller gardens garden for environmental reasons such as reducing waste sent to landfill or reducing greenhouse  gases.

 Herbivores. (grass grazing animals) such as cows, horses and  sheep, llamas, goats together with pets such as rabbits,  hamsters and guinea pigs, produce nitrogen-rich manure  that provides a good source of Greens and can be added as a layer manure layer  in a compost bin. Herbivore  manures compost quite quickly, often  in 12 weeks or less in a conventional metre square pallet bin. They  contain a different balance of bacteria species than the faeces of omnivores and carnivore and are less likely to contain as many human pathogens.  Manure from sheep, cows, rabbits, llamas, goats, hamsters, etc. are good “green” compost components having a  high in nitrogen and aerobic bacteria. When added to a compost bin the manure should be balanced by the addition of carbon rich Browns. 

 Manures make a good activator if added to a bin being used for garden or household waste:

  • as an addition layer when filling  a layered bin,
  •  it can also be added as an additional activator when turning (aerating) a New Zealand bin
  • or added and stirred into a Dalek style cool composting bin

 The values of manure and organic fertilizers in general, are often based on the relative amount of nitrogen (N), phosphoric acid (P) and potash (K) they contain. However, they are at least as valuable to the gardener as a source of organic matter.  Some common types of manure compare as follows (in N/P/K terms):

Manure

% N

% P

% K

Cow

0.6

0.2

0.5

Horse.

0.7

0.3

0.6

Steer

0.7

0.3

0.4

Sheep

0.7

0.3

0.9

Pig

0.5

0.3

0.5

Chicken

1.1

0.8

0.5

Rabbit

2.4

1.4

0.6

 

Source: Rodale Guide to Composting

 

 

 

 

 

 

 

 

 

 

Manure Fresh (Raw) or Rotted?

Maturing manure by compost bin.
This would normally be covered to prevent leachate

Manure purchased direct from the farm is unlikely to have been stored and allowed to rot  and while it may be tempting to use it rather than store it in the garden there are disadvantages. 

Raw (fresh) manure can burn plants with which it makes contact and there is a risk of transferring pathogens e.g.  E.coli, Salmonella sp.  from the manure to the surfaces of plants that are to be eaten.  Some  allotment plot holders apply fresh manure to an empty dug plot in the autumn and allow it to mature in situ over the winter relying on the worms to take it underground. Others may dig it in to the soil and leave it to overwinter. If succession growing and the plot  is not being left empty over winter the manure  should be applied at least 30 days before planting . Another disadvantage of spreading fresh manure on a plot   is that it is likely to have an unpleasant smell and while this may not be a problem when it is spread on fields, unless you live next to them, it is not welcome in a modern flower garden  surrounding the  houses.

 Most gardeners  will probably keep the manure  for at least a  year before adding it to the soil. Rotted manure, if stored covered to prevent rainwater, will have lost moisture as thus have a higher nutrient level per ton.

 However, when farm animals, or horses, are kept on the property there is a danger that so much manure will be produced that the compost heap  becomes the manure heap unless it is composted separately.

 The value of the manure from farm and domestic animals will vary with the type of animal, the age of the animal and the food on which it was fed. The value of the manure to the gardening will also depends age of the manure and the way in which it has been handled and stored.

 

 

 

 

 

Animal manures

Cow Manure

Cow manure is probably the most frequently used of the above manures. Cow dung is high in organic materials and rich in nutrients. Composting the manure before use reduces or eliminates the release of  ammonia and pathogens (such. as  E. coli or Salmonella). Hot composting will reduce or eliminates weed seeds and kill their roots. Using composted cow manure produces about a third less greenhouse gases  than using raw manure to fertilise the soil.

Horse manure

Warning: 2009/10 following problems products containing aminopyralid were temporarily withdrawn from supply, sale and use follow damage to crops grown following treatment with contaminate manure. Following investigation, new approvals were given by the HSE. Measures have been taken to ensure the risk of contaminated manure becoming available to gardeners have been reduced. The advice is that manure should not be accepted  from sources that cannot give assurances that the manure has not come from animals fed on grass or forage treated with persistent hormonal weed killers, especially aminopyralid products.

Horse manure has a higher nitrogen content than  other farm animal manures making it more valuable  to the composter but the concern over pesticide contamination may have added a concern over its use. Manures high in nitrogen  rich Greens are prone to fermentation and may be referred to as hot manures whereas those wetter manures with a lower nitrogen content which ferment more slowly may be referred to as cold manures. Manure is from horses usually contains viable weed seeds, to avoid the seeds  surviving the composting process hot composting of horse manure  is recommended. If cool composting must be used  the ground where the compost is spread may need additional hoeing.

 Horse  manure composts  easily, provided it does not dry out. If using a hot composting  system where, tuning is a necessary to the composting process, wetting the material when aerating  is advised. Ideally based on a scrunch test or moisture level reading.  If taken from the stable the manure  may include significant amounts of  wood chips and straw (browns) as well as urine.

A three or four bin system is probably advisable if horses are kept on the property as each horse  will produce approximately 22kg of manure and about 34litre  of urine per day to which must be added the  bedding. This will enable hot composting of the manure .

 Sheep manure

 Sheep produce  a relatively rich dry manure that has the advantage not being as smelly as some other manures. The same composting techniques can be used for Composting Sheep Manure as for cow manure.  

Goat manure

Goat manure can be composted as with other manures and can also be used as mulch. manure from cows or horses. Like sheep manure goat manure is low odour and some gardeners  broadcast pellets directly onto the soil.

The goat dung can be added  as a layer in a pallet bin or added and mixed with other materials in a Dalek bin.  The pelleted manure aids airflow within the bin  as does not form a matt as cow dung can.   

Pig manure

When I was a boy in Sussex in the 1950s  it was not unusual for a  householder to keep a pig in their garden  as an additional source of meat. The manure  was not usually composted but was dug into the garden soil in the autumn  to decompose over the winter  for the next spring’s crops. Pin manure  is best hot composted in systems that are turned regularly during the early stages.  

Chicken manure

Hens  may be kept on the allotment and at home making a regular supply of fresh manure readily available to the home composter. Chicken manure (usually including   woodchip or sawdust and/or straw from the bedding)  can be used in a layered composting system   such as the Indore method or as a layer into a Dalek or tumbler bin which can then be mixed with the other content.

Chicken manure is high in nitrogen and also contains a good amount of phosphorus potassium. It has had a bad reputation in the past  as if applied fresh it would burn plants compost overcomes that problem at it should be recognised by the home composter as a valuable resource. It also had a reputation of smelling and while this may be true of deep litter chicken houses in which the build-up of faeces and bedding led to high levels of ammonia. It will not be true of small garden and allotment chicken houses which will be cleaned out much more frequently with the manure being covered when stored and being composted

Rabbit and Guinea pig, Gerbil, and hamster manure.

 The manure from small domestic vegetarian pets can be added to the compost heap in the same way as with other herbivore manures although there is likely to significantly less manure. However, the bedding should be compostable  and while there may be insufficient bedding and faeces to make frequent manure layers in a  New Zealand or pallet bin it can be added to  another manure layer  mixed with greens . The material can be added and mixed with the normal waste in a Dalek type bin. of  manure layer in a pallet bin

Carnivore manure

It is not generally recommended to home compost faecal waste from meat eating animals e.g. from  cats, dogs and snakes is may contain potentially pathogen organisms but there are some methods available that can be used . For more details click the link Dog & Cat Poo

Manure as an addition to a conventional compost heap

Traditionally  manure  was added to the compost bin or heap in layers when using the Indore method of hot composting  or systems based on the Indore system. (Hot Composting )

 The Indore method uses alternating layers of vegetable material (mixed greens and browns) and  manure  to  fill a bin of a minimum size of 3 feet square and of about 4 or 5 feet high. The base layer  would normally consist of  a  3-inch layer of dry organic material followed by a layer of manure approximately two inches deep. This is followed by a further layer of dry organic material with alternating layers continuing until the material  is about four foot high.  Each layer should be watered  when it has been added. Traditionally the material would be covered with a layer of soil.

 The composting material should be turned every 3 days adding water if it shows signs of drying out.  Alternatively,  the temperature of the heap should be monitored it should be in the range of  450C -700C .  If it falls below 450C  it should be turned by moving to the next bin.  If the pile is getting too hot (over 650C -700C) it should be turned  as higher temperatures  will kill the composting microbes.  The compost is transferred to the final bin to mature  when it ceases to show any change in temperature and is dark brown in colour, has a  crumbly texture  and a pleasant earthy smell.

A variation on this  which makes it easier to achieve better control of the Green : Brown ratio involves  adding  the greens and browns as separate layers. This is  recommended if a non-turn method is being used. On an allotment plot or a large garden,  a two or three bin system is recommended with each  compost bin 3- 4-foot square pile. Pallet bins are excellent for this purpose.

When cold composting in a Dalek type bin manure can be added and mixed  with the decomposing  material  in the bin. Additional manure can be added when aerating  the compost provided it is  balanced with the addition of carbon rich Browns such as  straw, hay or cardboard. The addition of manure is particularly useful in a dry period if there is a shortage of fresh green plant material. 

Variation  for horse manure and bedding mix

The Indore method  can be varied to provide a system developed for a manure containing significant amounts of bedding.  A base layer of twigs etc. is used as a base level followed by layering 1" of green garden waste including lawn clippings with 3" of horse manure/bedding. Any  soft greens from the  garden can be mixed in this layer.  Bedding soaked with urine  will contain its own   nitrogen rich activator. If the manure contains significant amounts of bedding the thickness of the green  layer should be increased. Turning weekly over the first month is advantageous as it should speed up decomposition and prevent the risk of anaerobic areas in the bin producing greenhouse gases.