Making Compost Extract

The easiest and low-tech way of adding the microorganisms from compost is to extract them fro mthe compost using water and a mesh, then spray the water  – in our case using watering cans. You can spread the compost itself, and there’s much to be said for that, but it’s more stuff to wrangle and needs to happen before you plant, ideally. Since we are going to test areas on already growing plants, extract it is. Compost tea is a way of getting more microbes out there, but it is technically harder and we don’t have the gear. Extract it is, then. The rate seems to be about a good handful per 5 gallons, we used half an IBC, ie about 500 liters, which is 110 gallons. So we need about 20 times as much

Start with a wodge of compost in a net curtain

Start with a wodge of compost in a net curtain

and some reasonably clean borehole water (so no worries on chlorine or chloramine)

and 500 litres reasonably clean borehole water (so no worries on chlorine or chloramine)

We made a bag by putting the compost in the middle of the net curtain material and tying up the top with a releasable cable tie.

You can see the brown of the humic acid leaching out of the compost into the water

You can see the brown of the humic acid leaching out of the compost into the water

the end result is a dark brown chocolate colour

the end result is a dark brown chocolate colour

I looked at a sample of this compost extract with the microscope. The concentration of organisms seemed low, certainly a lot lower than the 5:1 sampling recommended for compost. This isn’t that surprising – there was less than 20% of the total volume of compost used, and the net material will have held back a lot.

The difference in concentration is immediately obvious - compost extract left, 5:1 sample right

The difference in concentration is immediately obvious – compost extract left, 5:1 sample right

Nevertheless I saw a few fungal hyphae that were wide and tan-coloured, and some testate amoebae

testate amoebae

testate amoebae

The end result was added to marked plots using a watering can. Some of the plots were given the compost extract, while others in the same bed were given water without compost extract to act as a control.

marked test and control plots

marked test and control plots

 

2 thoughts on “Making Compost Extract

  1. Gwill Jones

    Richard,

    Thank you for this link. I have a x400 digital microscope and your link has enabled me to get started.
    Any link that enables me to progress further in the microscopic analysis of compost would be most welcome.

    Gwill Jones

    Reply
    1. richard Post author

      Elaine Ingham’s website is your friend with this.

      Microscopy uk will tell you how to use a microscope. I started out with a student microscope, but it wasn’t up to the job, I got a secondhand Leitz ortholux from ebay. It seems most of the image quality seems to happen in the condenser lenses below the stage. It was also news to me that the coverslip was an inherent part of the optical system and without it you get softer images due to uncompensated spherical aberration. I think it was microscopy who taught me that 😉

      Reply

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