The Perfect Heap

Today, the 24th of November 2014 our Agriculture NZ 'Go Organic' class constructed a free standing aerobic compost heap using effective micro organisms.  This method can be used in a bin system but our tutor Micky wanted us all to experience making a free standing heap...no timber infrastructure is required and its easier to create and turn without the constraint of bins. The heap's location is at John Allen's lovely mixed farming property just a few minutes drive out of Pukekohe.

Micky chose a flat space with room for turning the heap.
This is the before shot!

Some of the class had never made a hot compost heap before and none of us had perfected the freestanding heap.  Micky Cunningham, our tutor, is truly a "compost queen" and introduced to us today the art of constructing a magnificent freestanding compost heap.

The finished heap and the proud team that made it.

For me the major changes in thinking about composting today were:
1. Its all about the layers  - no layer higher than 5 inches (7.5 cm)
2. The stick base up to the knees for aeration
3. Chimneys also for aeration
4. Activated EM for microbial inoculation (bacterial, fungal and yeasts) that will keep the heap working even if the conditions become anaerobic .

John chose the location in amongst his orchard and he generously contributed a large percentage of the required carbon materials (old hay and woodchips). We all contributed a variety of materials from our home gardens and kitchens.  Following is the diary of the construction:

We all contributed to the heap with Bokashi compost, vermicast,
garden weeds and hedge clippings, shredded paper, old yogurt and cream, comfrey,
egg cartons, Kitchen scraps, Biofert fertiliser, wood chips, horse manure in sawdust, horse manure,
and old hay.

1050: Began laying the stick layer inside the marked out area of approx 2.5 metres long by 1.5 metres wide.  First layer we laid the sticks with lots of branches lengthwise. Then cross wise (using the lopper to trim the shorter crosswise sticks. Care was taken at the ends to make the edges defined.   A bag of short cut sticks were added at both ends that gave the ends a strong foundation.

Ideally the stick layer would not have green attached but Micky
said that the green will decompose quickly anyway.

Avoid creating the centre higher than the edges.

It's important to keep those sides as high as the centre and you consistently have
to build up the sides.

To test if you have enough sticks in place you need to stand in the centre and the sticks will hold you up to knee height.  We did about four layers to get the strength the sticks will need to remain standing with the weight of all the following compost layers.

The stick foundation should be able to take your weight and not compact down
too far.  It's going to have to hold a lot of weight and if the sticks collapse then the purpose of
this layer would be lost - i.e. air flow through the bottom of the stack.

1110: Place Chimneys
Chimneys in the form of strong straight sticks or Micky's plumbing pipes that we used are worked into the stick layer.  These chimney's ensure air flow around the heap.

You can use sticks but they need to be without side branches and strong - so that they can easily make
a chimney without breaking and can be removed easily. Chimneys have to be standing straight to create straight chimney holes.

 Place three along the centre of the heap, and triangulate two on each side to have a total of 8 chimneys for this sized heap.  We were short of two plumbing pipes so two thick bamboo poles were used to create the remaining two chimneys. As the heap is made these chimneys are jiggled to make a strong wall that won't fall in when removed at the end of the process.

The plumbing pipes are easy to work with and you know they won't break
or have knobbly bits that make compacting the chimney walls difficult.

1112: Hay Mattress
The first layer is a thick layer of hay or straw biscuits. This is an insulation layer but will also prevent materials falling down into the stick area.  Important to use any solid bricks at the corners to create the strong rectangular shape of the heap.

The straw bed done - it's now ready for many thin layers. (Photo: John Allen)

Layer 2 - Green Nitrogen layer
A 20 cm layer of garden weed materials layered over the hay. Never push down.  A thicker layer of green materials for this first green layer.
- Any weeds with seeds were placed towards the centre of the heap.
- Important to constantly build edges to keep flat.
- Water as you go with a hose - slightly wet the materials
- Coarse materials on the lower layers, kitchen stuff in the centre, and lighter stuff like shredded paper at the top as its lighter lifting work once the heap gets higher.
- Never place a heavy bag or bucket on the heap - or it will collapse - treat it like soufflé!

We all soon found out that Micky's suggestion of filling buckets is easier than
trying to manage spreading materials from bags directly especially as you cannot lean
the full bags on the heap.  

Buckets are very useful for moving materials to the heap. (Photo: Linda McComb)

Layer 3 - Carbon
Wood chips make the best compost both in texture and produces a good quantity of material.
- Use hay specifically for keeping the corners in place for each layer of carbon.

Hay ensures the heap keeps it's good shape

- Wet layer and start to wiggle chimneys. Wiggling essential to create a good chimney wall - a little like rammed earth walls.

These pipes may look as if they are leaning but the chimneys they have
produced through wriggling and compacting the walls are upright

1125 Layer 4 - Green 
Hedge clippings with a scattering of lawn clippings - lawn clippings should never be more than a 2cm layer.  Treat lawn clippings like adding Jalapeño peppers to a meal.  They both have a big impact - too much Jalapeño and your food is inedible and too much grass clippings and you get a slimy anaerobic mess in your heap. 
- Add animal manure through the heap in small quantities as manure contains important biology that will assist in the breaking down of the heap.  We had horse manure and started adding from this layer.

Layer 5 - Carbon
Autumn leaves (using wet clumps of leaves to shape the corners)
- Another jiggle of chimney.
- Dry carbon materials need a good watering

Ngaire  ensuring the dry autumn leaves
get a good watering

1130 Layer 6 - Green
Hedge clipping with grass clippings and a sprinkling of manure.
A successful heap is about balancing materials - not only carbon and nitrogen layers but always changing the textures - e,g, fine (shredded paper) vs rough (wood chips).

Micky double checking that the chimneys are upright. (Photo: Linda McComb)

Layer 7 - Carbon
Hay around the edges with wood chip and vacuum cleaner dust and ripped up egg cartons.
Like building a sandcastle - mould the edges up with hay  like a moat to ensure the edges are at the same height as the centre.  

Egg cartons need to be ripped up and well watered  in order to break down
(Photo: Linda McComb)

Layer 8 - Green & EM (Effective Micro-organisms)
Kitchen scraps supply food for EM.
- Citrus if added needs to be right in the centre to cook.
- Scattered some vermicast
- Watered and wriggled the chimney sticks.
- Added EM to the heap via bucket with holes punched in bottom - its a gentle and easily manoeuvred method of adding the EM liquid.

Wriggling the poles to make the chimneys entails moving the poles in a
circular motion creating a compacted circular wall (Photo: Linda McComb)

Inoculated with vermicast - (Photo: Linda McComb)

The EM needs to be prepared in advancehe EM needs to be prepared in advance by mixing molasses and EM liquid - first dissolve molasses in hot water, add cold water and add EM to same proportion. We used 40ml each of Molasses and EM to a 20 litre bucket. You need a number of hours for the EM to activate so best to start the process the night before and just fill the bucket with water on site.
EM really helps a heap because this special bacteria can work even in anaerobic conditions. While the stick stack and the chimneys ensure the heap is as aerobic as possible when we cover the heap this sets up an anaerobic situation.  EM will keep the heap smelling sweet.

On layers we used about 5 litres spread by a bucket with holes drilled.

1150 Layer 9 - Carbon
Sawdust with manure with hay edges
- Inoculated the heap with a small bucket of compost sprinkled over this layer
- Important that chimneys are up right - the hole we are creating is straight not slanting.
- Water well if using sawdust.

1155 Layer 10 - Green
Comfrey
- add manure blobs to the green rather than the carbon layers
- Another bucket of EM over the heap
- Sprinkled like you would icing sugar BioFert with Trace Elements to ensure we are not missing any trace elements in the materials we are using.
- Added some grass clippings to the edges to get some heat on the edge.

Layer 11 - Carbon
Mix of Wood Chip and shredded paper.

Shredded paper is a good carbon source but it doesn't make bulk in a completed compost - it disappears
quickly. Good news - you can use coloured paper and printing as these are no longer toxic...but avoid shiny papers.

Only material we didn't have at hand was cow manure. Cow manure is the best manure to use to introduce a diversity of micro flora and fauna into your heap.  The cow has four stomachs in which food is digested using different gut microbes in each stomach.

This lovely cow kindly posed for me on a farm near Waipou.

Layer 12 - Green
Green soft woody materials and grass clippings.
- old yoghurt, soured cream diluted with water and poured over heap.

If the milk goes off or you have powdered milk that is out of date,
the compost micro-organisms will gladly eat them. Same goes for
even old crusty jam - micro-organisms like us need sugars for energy.
Always dilute with water to ensure the spread of the food through the heap.

1215 Layer 13 - Carbon
Hay at edges and wood chip
Hay works well to keep edges strong but will only break down once the heap is turned.

Layer 14 - Green (mixed platter)
Bokashi put in the centre, seaweed, lawn clippings, comfrey tea
Wet down

1220 Layer 15 - Carbon
Layer of wood chip before lunch with hay edges
Always when taking a break finish with a carbon layer to avoid flies and smells.

By lunchtime we had a good looking heap retaining its good shape.

John observed that the heap seemed to be slightly smaller than earlier.  Micky said that was due to the weight of the materials on the stick structure.  If we hadn't made as good a layer as we had then the heap would be on the ground simply because of the weight.

We discussed that the layers are the key - keep them thin so that microbes can do the mixing up of materials rather than us.  Thicker layers would mean turning the heap 4-5 times instead of 2 times.

1235 LUNCH BREAK (John determined to get some cow manure for the heap went to his neighbours property and collected a large bucket of fresh manure)

1315 Layer 16 - Green
Garden weeding, Bokashi (in the centre) and water with EM

1320 Layer 17 - Carbon
Shredded paper with straw edges
- Added some horse manure
- Wiggled chimneys
- Watered well

You can see the chimney walls being formed by the regular working of the poles
each layer

1322 Layer 18 - Green
Garden green waste and lawn clippings.
- Added Cow manure over the layer and mixed a couple of buckets of cow manure slurry so
that it would inoculate the lower levels of the heap.

A slurry is a good way of getting the microbial life
present in cow manure down to the lower areas of the heap.
We did this because the cow manure only became available towards the
end of the heaps construction.  Manure you tend to add with the green layers.

1325 Layer 19 - Carbon
Wood chip layer and ripped newspapers

1330 Layer 20 - Green
Bokashi, Bio Fert sprinkling of fertiliser, lawn clippings.

Don't add lime as this will discourage fungi to work in the heap. The heap starts out acid but by the time the microbes and compost creatures do their work then the heap will have a perfect pH. Adding lime is not necessary.

1332 Layer 21 - Carbon
Wood chip, straw edges with cow manure slurry.
- Watered well especially making sure all the hay edges are well wetted down.

Trish made sure we watered both sides of the heap and to especially
make sure the sides are damp as a lot of hay was used to keep the
sides of the heap straight.

1339 Layer 22 - Green
Lawn clippings
- watered down with EM

The EM is also added on the green rather than the carbon layers.

1341 Layer 23 - Final layer of Carbon
The top layer is thicker than the rest. Used wood chip.
Then layer of straw.
Watered EM over the top and sides
Decided to finish up all the wood chips on the top.

Here is what the chimney's look like once the poles are removed.
(Photo: Linda McComb)

The poles or sticks are now removed to expose perfect chimneys through the heap. The heat generated in the heap will circulate air via the stick base and the chimneys.

The chimney sticks are removed and all that is left to do is to cover the heap.
This was done with two pieces of carpet with a system of slits to allow easy access to the heap.

Taking the Temperature of Heap
You can use a dairy thermometer to monitor the temperatures of the heap but John will be using Micky's digital thermometer to take the temperature daily.   The dairy thermometer needs to be in place for 2 minutes before getting an accurate reading. The heap was 21.6 both in the centre and the sides.  John will take the temperature of the centre of the heap and the edge each day, ideally at the same time of the day each day. The ideal heat of 60 degrees Celsius should be reached in 3-4 days.
Click on this to visit John's record of the heaps temperatures:
Hot Composting Temperature Record

Why is it important to make a heap hot?
- relatively quick to make a useable compost
- no toxic by-product
- discourages any rats or mice taking up residence because it's too darn hot
- good way to deal with pests, some diseases and weed seeds (the heap needs to reach 60 degrees to kill weed seeds)

It's also bad for the heap to get too hot - too much above 60 degrees will kill the helpful micro-organisms working at this temperature.  If this happens the heap has to be turned immediately to get air through to cool down.

The compost process has a number of microbial shift workers workers changing with the temperatures. The worms will only come into the heap once the initial heat has lowered.

John has not only been taking the temperatures from the centre and edges of the
heap as required, he has produced a chart documenting the air temperature, the morning and afternoon readings
and with this information has created an online chart of the heap's progress. (So good to have an engineer in the class).

Carpet cover for the heap
Covering the heap is necessary (even though it will restrict air flow) because:
- it will keep the heap not too wet, not too dry and not too cold
- avoid weed seeds escaping into John's orchard
- uncovered it would dry out and nitrogen and carbon will burn off and escape into the atmosphere
- will keep the edge at a temperature where decomposition can occur

Gaps for air circulation are made by cutting slits or flaps in the carpet.

Talbot was in charge of cutting the carpet slits

The flaps will make access to the heap centre easier for John to take the temperatures.

A couple of the chimneys place some bamboo sticks to keep a gap between carpet and the heap.
(These later were removed by John because the strong winds were lifting the carpet, but in a sheltered position this will aid in air circulation plus take weight off the heap.)

1400 our heap is complete.  
With many hands at work this 23 layered heap was constructed in two and a half hours from first laying the sticks to covering up.

In two weeks time we return to turn the heap.

The compost team all admiring their work moments after completion

Update
One week after the heap was down John's chart shows that the heap hasn't quite hit the 60 degrees mark - sitting at around 50 degrees.  He thinks this has been due to the weather and the high winds. In hindsight a more sheltered site would be preferable but with a dozen people working on the heap you need space.  The carpet was blown off the heap one day so he has now secured it with some rocks.