Are compostable bags really compostable? Part 5 (final)

Part 5 of an experiment in home composting.

I started this experiment on 28 April 2019 to see whether The Guardian’s compostable bags do actually degrade in a home compost heap. I’ve added a few further items along the way, and am now checking up on everything for the final time this year.

I dug over the heap once more on Monday 28 October, eight weeks after the last check and 26 weeks after I started the experiment. Again, I removed all the material carefully with a spade and trowel, placing it as I went into a large bin.

The only possible sighting of the compostable cup which I had placed in the heap on 1 September was this small fragment.

However, it could be a small piece of cardboard from an egg box or similar. Either way, I think we can record this as something which has pretty well completely composted.

Further down I came across the Happy Pear compostable pouch which I placed in the heap on 4 August. It has still not decomposed much – if at all – as you can see from the picture below. I didn’t expect to find much progress on this, even after twelve weeks. The label says it is designed for industrial composting, so I’m not very optimistic that it will ever break down in a domestic situation. But we shall see.

I had to dig right down to the bottom of the heap to come across these very small fragments of the Greensax compostable bag placed in the heap on 28 April, distinguishable from the Guardian bag by the green printing. These are just a few centimetres in length. There was no sign of the original Guardian compostable bag.

These were at the bottom of the heap, so I concluded the experiment. Here is a report on all the items in the form of a table:

 Date  Item Completed
decomposition time
28 April 2019 Compostable bag: source The Guardian Approx 26 weeks
28 April 2019 Compostable bag: source Greensax Small fragments at 26 weeks
7 July 2019 Compostable wrap: source NJB Approx 8 weeks
4 August 2019 Granola pouch: source Happy Pear/TIPA Not yet decomposed
1 September 2019 Compostable cup: source Down2Earth Approx 8 weeks

I put all the part-composted material back, and have added a layer of fallen leaves and some more kitchen waste since. Now I am going to leave everything until next spring.

Part 1, 28 April 2019. 
Part 2, 7 July 2019.
Part 3, 4 August 2019.
Part 4, 1 September 2019.

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