Back in May we wrote an article on making compost. If you missed that you can read about it here
The other day we were asked to look at a customer’s compost heap that didn't seem to be working particularly well. We thought we'd write some more about why that seemed to be, what had gone wrong and what we did to improve it.
Let’s talk firstly about the two main types of compost heap – or bin. A popular type of bin – and one that in the past councils have been happy to supply free of charge or at a discounted cost are ones that look like this:
They’re made of plastic, come with a lid and have a small opening at the bottom so you can get your compost out. They seem fine in theory but in our experience they never seem to work quite as easily or as well as they might otherwise suggest.
Another of our customers was telling us the other day about how it had taken a couple of years for her organic matter to break down and that she’d found it difficult to be able to dig it out and turn it to help the composting process. Then when it came to getting it out of the opening at the bottom that too had been difficult and when she came to lift the bin away it simply broke.
That experience is enough to make you think long and hard about the merits of composting but fear not and persevere as there is another way.
Here’s another compost heap that we were asked to look at the other week:
This seems like a much more basic affair but in our experience can be much more effective as long as you follow some basic rules. This one is like the one we have at the allotment. It’s simply a few stakes that have been hammered into the ground and then has pallets fixed between them to create an enclosure into which you can then add all of your ingredients. Instead of pallets you could use chicken wire.
Perhaps making one might not seem quite as convenient as buying one of those plastic ones but if you can use a hammer and drill, and if you can get a few pallets then this is what we’d recommend.
We also need to consider where we site our heap or bin. Compost needs some heat to help the micro-organisms do their thing and to start and continue the whole process. It’s therefore a good idea to build your heap or place your bin in a part of the garden where it will get some sun. It’s also a good idea to have it away from the main part of the garden – some might say they aren’t the prettiest of things to look at! And it’s always a good idea to build them on the soil as this will encourage the all important worms to move into their new home.
So we’ve got our heap or bin where we want it. What do we need to think about next? Well the important thing is what we do and what we don’t put in it, and how much of the different types of material we have and use. This is where we talk about greens and browns.
Greens and browns.
Well these are simply an easy way to remember that you need to have elements of both in your heap or bin for the organic matter to break down as well as it needs to. The terms refer not only to the colour of those ingredients but also whether they are sources of nitrogen – greens – or carbon – browns.
Green materials mainly include wet or recently growing materials. Green materials are usually green or come from plants that were green at some point. In the greens camp we have:
Coffee grounds/tea bags
Vegetable and fruit scraps
Cuttings from annual and perennial plants
Annual weeds that haven't set seed
Manure from cows, horses, sheep or chickens
Brown materials mainly include dry or woody plant material. They include:
Twigs, chipped tree branches/bark
Straw or hay
Shredded paper and cardboard
Tumble drier fluff
There’s lots of talk about the ratio of greens and browns. Some say the ideal ratio is 30 parts brown to 1 part green or using 6 inches of browns to 2 inches of greens. The thing is neither are completely accurate as what’s important is the ratio of carbon to nitrogen of the heap itself. We need to understand that and consider it as it’s that which will influence how happy those worms and other micro organisms are and in turn how well they'll be helping the decomposition process.
Some of the organic matter that we’ll be adding to the heap will itself have different levels of carbon or nitrogen - irrespective of whether its a green or a brown - and we can spend a lot of time over-thinking it, worrying about it and then not actually doing anything about it apart from simply adding more and more organic matter onto the heap and leaving it all to chance!
So what did we do?
Well lets go back to that compost heap and look at what we found. Here's a couple of clearer pictures that show each side of the bin:
On the left hand side we seemed to have a lot of organic matter. On the right we seemed to have some compost that had already started to break down. However upon closer inspection what looked like compost was in fact topsoil. Not to worry though. In amongst all of this we were certain we'd find enough greens and browns and we were confident that it might simply be a question of mixing the ingredients in a more effective way.
What was good was that there were two parts to the heap. We'll cover why that's important later.
First things first was to clear one of the bays. We started with the one on the right whilst at the same time removing some of the contents of the one on the left. We had piles of greens and browns in front of us - from both bays - and then we chopped up some of our prunings from an old hedge to give us some more browns. Then we started to rebuild the right had side by adding alternate layers of greens and browns. It started to look like this:
We carried on until we'd reached 3/4 of the way up the pallets. We'd added some of that top soil, some leaves, some grass, some of the chopped twigs and some newspaper that we'd found in the other bay.
Then we had a good rummage through what was left in the bay on the left and in our piles of organic material that we had left.
This is what we found we had left to start that bay:
From left to right:
That old Christmas tree looks like a good brown. Not so sure about that plastic pot! That went.
Those shavings are another great source of browns. Although the bag was compostable it wasn't helping the shavings being spread about and worked on by the worms - that went too.
The old doormat. That might well have had elements of it that were organic but we pulled it out and got rid of it.
Newspaper is another good source of browns - but it needs to be shredded. We took it out, tore it up and added it to the bay.
And as for that branch! Whilst chipped wood or bark can be added we came to the conclusion that a branch with a diameter as big as your forearm would take ages to break down so that went!
What we also found was that a lot of the organic matter that was deep within each bay was very dry. The worms and other organisms need some moisture to help them do their thing and at times when the heaps gets too warm and dry it's often a good idea to water it. So that's what we did:
Now that the beds have been rebuilt all that remains for us to do now is turn them on a regular basis. That's where having more than one is a good idea - and it's also where the fun and hard work really starts. To get all of those worms and micro organisms doing their thing we ideally need to turn the contents once a month or so. Doing that gives everything a chance to breathe. And us a chance to see how things are starting to decompose.
And that takes us back to that green-brown ratio. Rather than worry too much about whether we've got that right - either in terms of the actual organic matter we've added or the ratio for the compost as a whole - all we tend to do is have a look at what's going on when we turn it.
If everything looks ok - in that there are worms there and it's all starting to decompose - then we leave it alone. If however we can still see some of the matter that's not starting or continuing to rot down then we have a think and take some action:
If the contents look too dry then we water them.
If the weather has started to get cooler then we might add a piece of carpet over the top of the heap to keep the heat in.
If we've not added enough greens or browns recently then we'd address that.
If we've added content that we know will take a long time to decompose - perhaps we added twigs that were more branch than stick - then we'd remove it.
And if that doesn't get things going next time then we might add a proprietary compost maker that might give everything a boost! Human urine can have a similar effect - but just be careful how and when you apply that!