Hot composting using coffee grounds

Recently I have been adding coffee grounds to my compost heaps and garden beds. Spent grounds have a ph of 6.5- 6.8 ideal for vegetables.Fresh grounds have a ph of 5 but most of the acid is removed when brewed. The grounds provide a source of slow release nitrogen as the worms and soil bacteria consume them. P , k and other elements are immediately plant available.

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Here I have spread some grounds around garlic. When used in this way an occasional sprinle is sufficient. Coffee grounds can be had for free from places like starbucks etc usually in little bags or if your lucky they will give you the larger bag from behind the counter. Even so in a modest sized garden they won’t stretch very far. I have been calling into local coffee shops recently to see if I can get access to the brown bins filled with grounds daily . By law the coffee shop cannot store these grounds up for you as they must be removed for the usually health and safety concerns.

Yesterday I hit the jackpot so to speak when I found a coffee shop who were happy for me to take as much as I wanted any time from their recycling area. They fill 1 brown bin per day on average. Companies like enrich are developing new richer composts using these types of materials and will be selling this back to the general public. On a smaller scale at home one can do the same.

One of the upsides of living in an urban environment is the availability of resources. They are quite literally everywhere. The trick is to take only what you need.The bike shop, lidl and aldi provide sources of cardboard for mulching, no dig beds and carbon for composting, Most of the time they are only too delighted to give you some. Just ask at quiet times of the day. A stack of clean cardboard out in the rain is ready for when you have a lot of greens like grass clippings for your heap. Its similar to storing woodchips etc for compost use. In previous post I talked about how arborist are only too delighted to drop woodchips to your driveway as fuel cost rise.

Another fantastic source of carbon materials are pet shops. They change the sawdust and hay beddings twice a week where I source mine to prevent smells. If you live close by you can include a pickup within your routine.This material is still extremely clean just ask if they use strong chemicals in cleaning out the hutches. Some us a coloured edible cotton for some small animals but this composts. My local shop sets aside about 40 to 50 litres a week. Provided you don,t mess them about by not showing up it’s a mutually beneficial arrangement.

To break down the sawdust and hay I used this as bedding for the ducks within their enclosure. As I mentioned before its really clean ( 3 days old) I put fresh bedding in their house. Muck whats inside out ( ususally still very clean) and muck whats outside into a bucket to add to the compost heap. This way the material is already pre mixed with droppings and rained on. The bacteria will be working away on this. Image

I put bits of cardboard in here too, they wont blow away in the wind and the rain softens them for easy tearing on bigger bits. The “golden gark” (rake shovel and sieve) is on it way to help with this job.

On saturday I gathered together materials to make a hot heap within a small composting cone. The materials are coffee grounds, sawdust bedding from the rabbit, and ducks bedding, spoiled vegetables , spoiled apple juice and handfull of soil. The cone was already half filled with “weeds” bedding etc.

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Steps to achieve a hot heap.

1.It’s all about the layering then mixing( aerating) When I looked in the bin there was green material so I added browns. In goes the rabbit and guinnea pig droppings.

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2.  This material has a high c:n ratio perhaps 400:1 so I need to now put a lot of “Greens” in. This means nitrogen and while we refer to this as adding greens they may not actually be green in colour which may cause some confusion. Better to think in carbon / nitrogen I think as some greens like grass when old and dry act as browns !!

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mix it all up a bit .

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4. After putting in the coffee grounds (nitrogen) I put in some torn up cardboard. As this is dry it needs to be moisened.

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5. Next in a half bucket of spoiled veg.

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6. Bedding material and coffee grounds.

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7. More bedding from ducks enclosure.

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8. More spoiled vegetables.

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9. Some more coffee grounds.

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10. Some more bedding material.

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11. More coffee grounds

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12. I now use this compost aerator to mix up the layers. The more mixed up the better.

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13. Put the lid on and wait

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The mix should have the moisture consistency of a damp sponge. You don’t want the water filling in all the air pockets within the materials. I have a compost thermometer on it’sr way so will monitor the heat buildup. It shoud take a few days to heat up and need aeration after a week. As the mix slumps I will add a little more materials to the mix repeating as per above and then at some point stop adding new material and allow the compost to mature. Building a heap in a short space of time is important for a hot heap. We turned a pile in work the otherday and it was beautiful. If you turn your compost once a week with a good mix it is possible to have compost in 12 weeks.

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