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extreme composting – turning up the heat

October 27, 2012 Charles Dowding, Gotalottie, Tips 3 Comments
composting-horse-manure

Those of you interested in the concept of no-dig gardening, will have no doubt read, or at least heard of the work of Charles Dowding. Charles has written a number of extremely informative books on the subject and has a website which is an absolute mine of information, for those interested in the organic nodig approach.

The method that he advocates is for slightly raised beds with no formal structure to the edges of the beds; instead, the beds are allowed to gently slope down onto the adjoining paths and require minimal maintenance.

some of Charles' excellent books

some of Charles’ excellent books

Charles has manually re-constructed his soil structure over many years, by the addition of mulches at various points during the year. Horse manure forms a large part of these mulch layers and Charles is careful to ensure that this is thoroughly composted over a couple of seasons, prior to its application. I’ve never had the pleasure of visiting Charles’ farm, but speaking with some who have, it’s said that there is a lot of raw material on site, it is always well composted and it is very well utilised in his beds.

one of Charles' extremely productive beds - undug for 14 years. Photo courtesy of Charles Dowding

one of Charles’ extremely productive beds – undug for 14 years. Photo courtesy of Charles Dowding

Unfortunately, many of us don’t have the space on our plots to store vast amounts of horse manure and as a result, semi-composted material is often spread and lightly dug in.

It’s a well-known, but often overlooked fact, that horse manure contains vast quantities of weed seeds which can pose a significant threat to our beds. If horse manure is stored in bulk, there is a natural decomposition, which generates a degree of heat, serving to destroy these weed seeds and any unwanted pathogens, which would otherwise be introduced to our soil.

 It all sounds so easy.

manure pile - location unknown

manure pile – location unknown

In reality, if the pile is small, it will not heat up correctly; there will be areas at the extremities of the pile that will still contain active weed seeds and potentially dangerous pathogens might not have been fully exhausted. A man-made herbicide, known as aminopyralid – a real risk to anyone using animal manure to nourish their allotment or garden, is long lasting and might be transferred from the grass eaten by livestock and into their manure. It is possible to determine whether this is being used on the fields of the donor farm or stable, but in reality this might be being transferred from feed which has been bought in. I’d certainly not take the risk and feel more comfortable, when all the manure has been subjected to some serious heat.

 There is a method of composting known as the ‘Berkeley’ method, which advocates the regular turning of a well-mixed compost pile, which will create temperatures of around 55-65 degrees Celsius at the core. Regular turning and re-moistening will ensure that the pile is kept aerated, thus feeding the bacteria which create this heating process, thus ensuring that all of the pile is treated. It is labour intensive.

 A pile which contains approximately 1/3 manure (green material) and 2/3 bedding (brown material) is going to shrink in size by approximately 50-60%. As a result, you should expect to double the volume of the raw material in accordance with your expectations of volume of finished compost.

 The hot composting of pure horse manure will, however, result in a minimal shrinkage of the raw material, this is largely a result of the absence of the bulky carbon-rich constituent – straw.

4 degrees outside, 60 degrees inside - breaking open one of our piles

4 degrees outside, 60 degrees inside – breaking open one of our piles

 We’ve been bringing in large quantities during the last 3 weeks, from a reputable supplier and have created several piles of approximately 1.2m height; these are regularly turned, re-moistened and covered. The core temperatures are now reaching around 60 degrees Celsius; however during the last 2 weeks, outdoor temperatures have dropped and last night – we had snow. These cool air temperatures will have an effect on the heat being created in the pile, with only 1/3rd or so getting hot enough – the material in the centre.

 This morning, I took the decision to combine the piles, placing the bulky, un-heated material from the outside of each smaller pile onto the bottom of a new combined pile and covering this, with the material which has been subjected to some heat already.

moving un-heated material to the centre of a new combined pile

moving un-heated material to the centre of a new combined pile

the finished combined pile - a lot of poo!

the finished combined pile – a lot of poo!

The combined pile is now in excess of 1.5m height, 2.5+m wide and 5+m long; this should create more efficient cooking within the pile and a reduction in heat loss from the reduced surface area.

protected from the worst of the elements - for another 'cook'

protected from the worst of the elements – for another ‘cook’

 After only 3 weeks, despite the drop in outside temperatures, nearly half of the material has become quite crumbly, is taking on a brown colour and with no unpleasant smell whatsoever.

 We have a way to go yet of course, we’ll need to keep this pile active and we probably need to  create another two. If the weather continues getting worse, we might have some fun.

We have a new toy, something to help our composting; the eagle-eyed reader may have seen this already - we’ll tell you about that later.

Currently there are "3 comments" on this Article:

  1. wellywoman says:

    Charles Dowding is a very inspiring man and I would definitely recommend one of his courses. I’m so envious of your pile of poo. Manure envy strikes again!!! Still on the search for a good supplier here and the space to put it.

  2. Diane says:

    Did you manually move all that? I’m pretty impressed if you did! :)

    • royw says:

      yes, all in bags. Then we made 2 large piles and now they’ve all been moved further back up the plot and into one larger pile. The worms have moved in now and are breeding at a crazy rate, we’re nearly ready to spread this now.

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