Is it worth sieving your compost?

 It depends! For years I have use my compost 'au naturel', i.e. lumpy with plenty of woody bits in. Used directly on the soil as a mulch or hole/trench filler before planting out fruit and vegetables, it will enrich your soil, improve its structure and help retain moisture during those inevitable dry periods. This is by far the best way to use compost because it retains all the good things you have nurtured during the composting process: worms, bacteria, fungi, invertebrates, soil carbon, nutrients and humic acids.

On the other hand, I have to buy in seed & potting compost which is an added expense. We have been very happy with the coir-based products bought in from Fertile Fibre, a local Herefordshire company that delivers nationwide. Peat-based products are a definite no-no here. An alternative we can also recommend is the Dalefoot range made from composted bracken and sheep's wool. While my opinion of upland sheep farming is that it is unsustainable (both financially and ecologically), Dalefoot gets my thumbs up for its work restoring degraded peatlands, an important carbon source for mitigating climate change. It is an excellent growing medium which also acts as its own slow-release fertilizer.

I have sifted small amounts of compost with a hand sieve but this is slow and hard work. A rotary sieve can handle larger amounts and easier to use. My Clarke rotary sieve arrived a few days later. Simple to put together it was sieving compost with 30 minutes. Easy to use by putting a couple of spadefuls of compost in the basket and then turning the handle in a clockwise or anti-clockwise direction or a combination of both. I'm still not sure what the purpose of the spring is as it seems to fulfill no useful function. The black handle can also unscrew during use. You can either collect the sieved compost in a container (wheelbarrow, trug, bucket) or just place the sieve on the soil where you want to apply it.

The photo below shows what can be produced in less than 10 minutes sieving. Starting material in the black trug, sieved product in the yellow trug. Material left in the sieve (about 10%) will be recycled through the next composting process.

When sieving, take care to rescue any worms and invertebrates which can be added back into the compost heap or sieved material.

The rotary sieve costs about £40 so could pay for itself very quickly. Half-an-hour sieving produced about 200L of sieved seed/potting compost with a commercial value of at least £25.


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