Both of our current compost heaps, 160901 and 160910 have now reached stable equilibrium. The two graphs below show the complete “heap lifetime” temperature against time. The tail of each chart is now reasonably steady, suggesting they are now “mature”. It’s between five and six weeks since we first built these heaps.
The complete “lifetime” temperature profile of compost heap 160901 started on the 1st September 2016. The second probe was first at a different level within the heap, and then reallocated to monitoring outside temp at the start of week 37Temperature profile of the heap using chicken manure slurry, heap number 160910, showing the much faster burn initially
In both of these there seems to be a reasonable evenness through the pile when both temperature probes are active, the temperature recording tips of the probes were set in the centre of the pile horizontally, and at about 1/3 and 2/3 from the top of the compost heap material.
We had a quick look at 160901 compost under the microscope a little while back and it was very exciting!
Fungal hypha in heap 160901Bacteria and protozoa, magnification 400x in heap number 160901Another fungal hypha
The heap is now dropping below the 66 deg C temperature mark so the outer wrapping was replaced around 1pm. Today is a hot day, the highest September recorded for many years, so the heap has ambient temp on its side.
This heap heated up far more successfully than any of our previous heaps! and we look forward to putting some of the matured compost (when it has dropped ambient temperature) under the microscope. We put this sucess down to the pelleted chicken manure pellets mixed into a slurry with water which raised the temperature dramatically!
Outstanding issues:
It is possible the fast high burn rate of the early stages has exhausted the material, or that some was pasteurised at 74C?
The temperature profile isn’t 100% perfect, but it is certainly very promising.
After the drama of needing to turn this heap very early on a Sunday morning (we had obviously overdone the chicken manure slurry) it heated up over the day so we turned again at about 19:30 Sunday evening.
Before the turn.Heap uncoveredclose up
This time we left off the insulation around the outside of the container, though retained the insulation in the top made of bundled up mypex woven black weed control fabric.
This graph shows the temperature against time/date of a new heap that included a slurry of pelleted chicken manure, as explained in this earlier post. There is a gap in the data near the top of the graph – Richard had an upper limit of 70C on the data logger which he swiftly raised as a result!! You may notice that the rapid rise of temperature to danger point happened at approximately 5.30 am on a Sunday morning. Yes, this meant that Joanne woke Richard at this time to tell him, “the heap is going anerobic!!!” (very worrying and could cause a fire!) so we rushed up to the farm to turn it…!
overheating compost heap, turned in the morning at about 6amheap contentsHeap had gone down about a third (it wasn’t loaded to the top before, down to about the first set of holes probably)Close up of outsideShowing inner core. It really was hot!detail of photo above.Turning the heap
New heap declared, using about a third of a 20kg bag of pelleted chicken manure dissolved in water to a liquid/slurry, to see if raising the N will help with the fade problem that affected heap 160901
We used only about 3/4 of one wheelie bin of wood chip so mental note to only prepare one next time for the black plastic composting container!
Allocated transmitter AT with fresh batteries today (for monitoring temperature).
all the materials collected with the team10kg of pelleted chicken manure dissolved in water, about 7 kg used
Other materials:
Some sweetcorn and mostly french beans – 4 wheelbarrow loadsNettles and comfrey: 1 wheelbarrow loadGrass and clover with some nettles: 1 wheelbarrow loadShredded evergreen leaves from Joanne’s old allotment neighbour, Rob’s, clippings: 1.5 wheelbarrow loads usedCrew: Josh, Glennis, Richard and Joanne chopped beans & sweetcorn laboriously using spades and shears!Deployment of the chicken crap, which was then lightly mixed in with a garden fork
The whole heap was pressed down and then insulated with two lengths of black plastic above heap, and another length wrapped round fairly loosely to allow airflow. Used mist sprayer to wet all except pre-soaked woodchip and the chicken shit slurry.
