How to make a great hot compost pile

I have been working for most of the afternoon making a new compost heap and taking photos for your viewing pleasure. Although I think compost is great for the garden, I also think that it is a lot of work, so it pays to get it right!

Since I have started to keep chickens my scrap bowl (in the kitchen) has turned in to two scrap bowls (one for the chooks and the other for the compost) and the compost bowl contains hardly anything other than a few potato peelings and onion skins. All the green garden waste gets thrown into the chook run where it is either eaten or de-seeded and comes back out as mulch. My main use for compost now is for my market garden beds and as part of my seedling mix, but finding the materials to make compost is now much harder than pre-chicken life. I have, however, solved the problem, but before I go into that with a future post, I thought should do a simple “How to make compost”.

The ingredients required to make compost are a mixture of things that contain nitrogen, such as food waste or grass, and carbon things like straw or leaves. These are mixed to a specific ratio. Many people debate about this ratio but I will tell you the way I was taught and I have yet to find a better ratio (and I have tried other ways). I was taught to use a carbon-nitrogen ratio of 30:1 however in practice this looks more like 3 parts carbon to 1 part nitrogen! I don’t want to get too ‘science-y’ here and explain why it works that way, but you can read this great book called The Rodale Book of Composting if you want to learn more about the nitty-gritty of composting.

The materials

I reluctantly (after many discussions with Michelle) agreed to keep a small section of lawn in the front garden for children to play on. Things need to be useful in my garden, so instead of a traditional lawn, I have sown nice fluffy stuff like lucerne, wheat, oats, clovers, lupins and other nitrogen-fixing grasses, which can be neatly mowed should the occasion arise (parties etc.). I let it grow for a few months and then slash it to make the nitrogen-rich part of my compost mix. I have other areas of tall grass that were slashed a few weeks ago and left in place to dry and this dry grass becomes the carbon part of the compost mix.

slashing the clover and lupins

raking dry materials

Raking dry materials

Next, I took a load of soiled lucerne hay (more carbon) from the chook run  and I also found a two year old bag of cow manure (nitrogen) under the house to add for good measure. A couple of other ingredients that I add are old finished compost (which activates the composting process) but you can also use any soil for this so don’t be fooled in to buying compost activating products! The last ingredient is wood ash. Not only does wood ash contain potash it also lowers the acidity of the compost in the same way that lime can be used.This is important because most plants enjoy a relatively neutral pH soil.

My compost bays are in my carport which not only beautifies my front garden, but actually serves a practical purpose. Making compost gets messy, and having compost bays on grass or earth soon creates a slippery mud bath. Keeping my bays on concrete allows me to mix my ingredients on the concrete beside the bays and clean up afterwards very easily.

The compost ingredients

The process

To start making the compost you need to make small batches of your ingredients so you can mix them thoroughly before adding to the bay. If you are on dirt or grass then I would suggest that you use a wheel barrow to make the mix.

Add the ingredients bit by bit according to their purpose. Take some of the brown grass and lucerne (carbon) then take a small amount of the green grass (nitrogen), a couple of handfuls of manure (more nitrogen), wood ash (potash) and a small sprinkling of aged compost (starter) and mix it thoroughly. I use a fork but it you are using a barrow then hands are better.

Once it is mixed, add some water and mix again until it is damp throughout.

Watering the mixture

Add the mixture to your bay and keep the mixture fluffy and aerated (not soggy and compacted) as you do so. I used a garden fork to do this.

Mixing the ingredients

As you will see in the picture, my bays have mesh in the bottom. This not only helps the heap heat up (by allowing air underneath-  just like a combustion stove or convection oven) but stops the bottom layer from becoming saturated with water.

Suspended mesh bottom

Repeat the process of mixing, wetting and adding, until you have used up all your materials. The compost heap needs to be a minimum volume of one cubic metre for the hot composting process to work correctly.

After about two days the heap should be about 50-60 degrees Celsius, which is enough to kill most weed seeds and pathogens; any hotter and the beneficial microbes and bacteria start to die.

You can turn the compost heap as often as every two days and it will be ready in about two weeks but since it is quite a big job I prefer to turn it every two weeks and it is ready in 12 weeks. This extra time also makes a better, more composted compost!

The finished pile

Once the compost is finished, I bag it and leave it for as long as possible. Some people leave the compost for up to two years before using it.

Let me know if you need any help. Happy composting!

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About Healthy Harvest Kitchen Gardens

Healthy Harvest provides a permaculture-based kitchen garden service for existing food growers and people who are inspired to grow food. We sell fresh chemical-free seedlings, seeds and seasonal produce. We also provide educational workshops, courses, gardening consultations and services. We can help with new vegetable garden designs, maintenance of established gardens, or converting and improving existing gardens ready for growing food. Please see our website for more information: www.healthyharvest.com.au Check out our blog at https://healthyharvestnsw.wordpress.com/ for news and interesting bits and pieces.

Posted on July 19, 2011, in Compost, Gardening techniques, Soil. Bookmark the permalink. 1 Comment.

  1. To be clear, I will completely fill that bay up but I got caught out in the rain and was unable to rake up more supplies! It will be raining until this weekend but I will continue the process as soon as I can.

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