Is your HOTBIN compost good, bad or fabulous?

We do not know the answer – only detailed testing will prove things one way or another.

What we do know is this – composts differ in physical structure and chemical composition. HOTBIN compost often appears much wetter and sticker than other composts. We believe some composts will be better for soil fertility than others. We believe those with higher humus content will be better for your soil and hence plants and vegetables.

We have a some evidence it might be better. This is related to the physical properties which in turn we believe are linked to higher humeric substance content.

Humeric substances are the essential component in compost that delivers the benefits – the more humeric substances in your compost the better your compost. It also is the case that the more humeric substances in your soil the more fertile your soil.

To explore if composts are different, we can look at the analysis of composts.

Ask a gardening expert to describe good compost and you may well get a list like this:

  • It smells earthy (not putrid, acrid or drain like?)
  • It is fine particles with no sign of original waste or big bits
  • It is a dark brown material

Some might add a footnote that peat is not compost, farm manure is not compost and that the term ‘humus’ is better reserved to describe ‘very well matured compost’.

Ask a worm composter (vermicomposter) what good compost is and they will probably say:

  • Worm cast / vermicompost is the best compost
  • It smells earthy
  • It is always fine particles with no sign of original waste or big bits
  • It is dark brown
  • It is ‘extra good’ as the worms leave a sticky mucus (from digestion tract) in the compost that promotes mycorrhizal root zone activity

Ask an industrial compost maker and you should get the following:

  • It meets the PAS 100 standard
  • The C / N ratio has been tested and is within spec for “stable and mature” compost
  • It all passes through a given mesh sieve (ie below 8mm particles)
  • All potentially toxic elements (e.g. mercury, heavy metals) are below the guideline levels
  • NKP will be present, but compost is a soil amendment not an NKP fertiliser, so we only measure them in some compost formulations.

Ask a soil scientist to describe compost and they will struggle!

It has no scientific definition – they will refer to “Soil Organic Matter” (SOM). This is the total sum of all dead plant and animal matter in the soil – it excludes roots, living plants, living worms and bugs). They measure the labile part (compostable to you and me) fraction and the non-labile fraction (the bit that resists further decay and is known as the humeric substances fraction. They will then offer you +10 soil types, each with a different ratio of sand, clay and SOM.

The ‘fertile soils’ (what gardeners want) typically will have:

  • SOM of 2-10% (UK norm 2-4%)
  • Within this, humeric substance content of 1-5% (i.e. 50% total SOM)
  • A fertile soil is a balanced mix of SOM, sand (silica) and clays

What if you Googled ‘best compost‘, or ‘the world’s best compost‘?

  • There are claims and methods that profess to offer “colloidal compost”.
  • There are methods such as Luebke, CMS, biodynamic and QR that all purport to make fabulous compost

And what if we ask the HOTBIN expert (Tony Callaghan, head of R&D at HOTBIN) to describe good HOTBIN compost!

  • It smells earthy (not putrid or drain like)
  • It is fine particles with no sign of original waste or big bits
  • It is a dark brown material
  • It is very wet and sticky – so much so it appears ‘large and lumpy’ – but looks can be deceptive – for more information see the FAQ on sieving compost.
  • When dried, about 80% will pass through an 8mm sieve, 5% will be oversize (too large) and 15% will be 0.5-1cm pieces of wood chip (bulking agent) coated in humus.
  • It will be pliable i.e. show signs of high levels of colloidal humeric substances
  • The C/N ratio will be in the “stable and mature” zone (when tested using the Solvita compost test kit)

We have found no definition or standard that can be laboratory tested for a good, bad or fabulous compost. Only tests for ”stable and mature compost’. There is no system that routinely tracks ’cause and effect’ for any difference in compost quality directly back to a composting method.

The question remains: can one compost method deliver better compost than another?

There is ample scientific evidence that nature’s composting (i.e. on/in the soils) does produce different levels of residual humeric substances – varying from 0 and 3% depending on a range of conditions (soil structure, temp, water, oxygen).

The HOTBIN is composting outside the soil environment. The HOTBIN (subject to correct operating practice) offers a degree of control and conditions not often encountered in most soils or even most compost bins!

Does the HOTBIN deliver a better, richer compost than any other compost bin?

We do not know the answer – only detailed testing will unravel this.

However what we do know is this…

Composts differ in physical structure and chemical composition. HOTBIN compost often appears much wetter and sticker than other composts. We believe some compost will be better for soil fertility than others. We believe those with higher humus content will prove to be the best. We have some evidence it might be better based on the physical properties and that these properties are potentially linked to higher humeric substance content.

Why not join the debate and help us sort this out.

We need to define and analyse what makes fabulous compost. This has to be tested by soil science labs, it has to follow all the norms of science (evidence, repeatable methods).

If we have a standard for the very best compost, it is pretty easy – You never know we could even have an annual competition and give a prize for the best compost and best composting method!

 

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1 Comment

Filed under Compost, In the news

One response to “Is your HOTBIN compost good, bad or fabulous?

  1. Pingback: Compost – Looks can be deceptive! | hotbincomposting

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