Why should I compost?

‘I don’t garden so why should I compost?’ This was what a friend said to me recently.

Where to start to answer this question?

Composting is of course an obvious activity for gardeners – you make your own top-quality plant food by recycling your organic waste, including garden waste.

 Like my friend, I too am no gardener.  I started growing a few things during the pandemic and finally realised, when I saw the transforming effect of plants, why gardeners do what they do.   

But the point I tried to make in answering my friend was that it wasn’t for the sake of plants that I started composting but for the sake of the soil itself.

A health soil sign that reads 'Healthy soil is the beating heart of organic growing - full of life and support life'.

 When I learned a few years ago what magical powers compost has in rebuilding the poor, degraded earth of the Earth, I realised that composting was a no-brainer.

The health of our soils is fundamental to life as we know it, but according to the charity Garden Organic, half the planet’s topsoil has been lost in the last 150 years.

And yet there’s something we can all do about it! Home composting might seem a small act on an individual level but multiplied by millions it’s huge.    

Climate crisis ally

For instance, did you know that one of compost’s superpowers is to help soil capture carbon in the atmosphere and pull it down into the ground? Along with oceans and forests, soil is an important carbon storage medium. And yet we’ve been letting the organic ingredients for compost rot in landfill for years, emitting greenhouse gases instead of capturing them. It makes no sense to throw nutrients away as rubbish when we can easily separate them to speed up the natural breakdown process.

 According to WRAP, the waste reduction charity, a home composting bin can divert approximately 150 kg per household per year of organic waste from landfill or treatment centres.

Save our soils

The minimum we can all do is to ensure that soil is not left bare. Bare soil is vulnerable to erosion, weeds and carbon loss.

  • Cover soil with mulch and just leave it. Chuck it on in layers of around 5cms. You can cover borders, around shrubs, trees and bushes. Worms will come up and take the compost back down into the earth where it will improve the soil structure.
  • Compost also helps worms to thrive, and they need all the help they can get, under onslaught as they are from chemical sprays, artificial grass and the paving-over of gardens.    
  • Give your lawn a boost by spreading compost thinly over it. Worms will pull it down into the soil, which will boost soil quality and by extension the grass.

Benefits for us

Michael Kennard (pictured) the founder of the food waste collection service Compost Club, has studied soil biology and is keen to spread the word about how soil is the foundation of our health. If we destroy it, it’s to our detriment.

‘Everything is a reflection of the soil,’ he says. ‘If the plants have that natural cycle going on, they’re really healthy. When we eat those plants, that’s what informs our gut health.’

Other benefits that compost provides include:  

  • preventing erosion
  • improving drainage
  • encouraging worm activity. Studies have shown that the simple act of introducing worms to degraded soil in poor regions of the world has increased plant yields by 280%.
  • preventing flooding. As more and more gardens are paved over there is less and less earth to absorb heavy rainfall. In order to slow down runoff and encourage water infiltration into soil, swap paving for plants and mulch, or ensure paving is permeable. In his book The Science of Gardening, Dr Stu Farrimond says that covering soil with mulches in late autumn protects it from pummelling winter rainfall (each bullet-like drop travels up to 20mph).

Benefits for plants;

Used on plants, compost holds on to important nutrients, improving the plant’s quality while also protecting it from pests and diseases.

 As compost breaks down further, it releases important nutrients into the soil, including the main nutrients that plants need: nitrogen, phosphorous, and potassium. Compost also increases the number and variety of beneficial bacteria and fungi in the soil, which helps plants to grow.

The ability of compost to absorb water is important as it’s able to slowly release water to grass and plants so they need watering less frequently. This is obviously vital in hot weather and droughts. Studies on compost’s water-retaining abilities have shown that for every 1% of organic matter content, soil can hold 16,500 gallons of plant-available water per acre of soil down to one foot deep.

Compost also helps water to get to plant roots more effectively by reducing crust forming on soil, so water can get into the soil more easily, and by helping to disperse water laterally from where it hits the ground, which means it will evaporate less quickly.

But I don’t have time to compost

Composting can be as time-consuming as you want to make it. If you’re pushed for time, go for cold composting.  If you want to invest a bit more time and effort, try hot composting, which means a wider variety of food waste can be added to the bin and compost produced faster.  

Or use bokashi bins, which ferment food waste thanks to the addition of beneficial bacteria in the form of a bran or spray. Once it has been left to ferment for a couple of weeks, this pre-compost mixture can then be added to a composter.

People whose local council operates a food waste collection might think, Well the council composts my food waste, so I don’t have to. But many people take the view that if they are already separating food waste to leave out for the council to collect, they might as well compost this valuable resource themselves at home for the benefit of their own garden or allotment.

 By 2026 all councils throughout the UK will have to comply with regulations requiring them to operate separate food waste collections.  

There are around 15 million gardens in the UK. We call them ‘our’ gardens but of course that portion of the earth isn’t really ours – we’re merely its custodians for a while.

Once you see the difference you can make to that tiny patch of the planet, without much effort, you can’t help but become a compost convert.

Julie

When is my compost ready to use?

This was a question that two new owners of a Green Johanna were asking themselves in their first year of composting. 

Adam and Hayley decided to try composting with a Johanna last year following a few failed attempts with other composters.

They’re both vegans and wanted to produce their own compost to use for growing their own veg, as well as recycling their food and garden waste sustainably.   

  The standard test for when compost is ready for use is that it is dark brown in colour, crumbly in texture and has a pleasant, earthy smell like damp woodland. If you’ve been hot composting, the mature compost will no longer be generating heat. The original materials should not be recognisable. There may be a few items that have not fully broken down, such as sticks, bits of tea bags, corncobs, eggshells, fruit stones, compostable bags – these can be picked out and added back into the next batch of composting material.

 If there are other recognisable waste items and an unpleasant smell, the compost is not ready and should be left to continue breaking down.

Master composter Rod Weston, in his book A Gardener’s Guide to Composting Techniques, suggests a test to check if compost is ready if you are wanting to add it to soil immediately (immature compost added to soil can cause a temporary reduction in the availability of nitrogen and oxygen and create root-inhibiting organic acids).

The test involves putting a handful of compost in a plastic bag and sealing it for three days at room temperature. If when opened the contents have a pleasant earthy smell, composting is complete.

 Rod suggests that during the growing season immature compost is best used as surface mulch. If mostly composted it will finish breaking down in the soil. In autumn and winter it can be dug into garden beds. Some people prefer to leave their compost breaking down over winter to have it ready for the start of a new growing season. 

Horticulturalist and author Charles Dowding encourages a relaxed approach to the final product. In his No-Dig Children’s Gardening Book (also a good read for adults) he says that mature compost can be anything from ‘slightly lumpy and fibrous to quite fine and soft’. It all depends on the materials that went into making it and they will all decompose at different rates.

‘It doesn’t need to look perfect – woody bits in your compost make great food for fungi.’

He cautions against sieving compost as it can damage microbes.

What’s the difference between compost and humus?

The term compost describes materials that are still breaking down whereas humus is what’s left when breakdown is no longer taking place and the usable chemicals in the organic matter have been extracted by the micro-organisms.

It takes years for compost to decompose into a humus state. Even mature compost isn’t really ‘finished’ since bugs and fungi still have material to work on. Some gardeners have a bank of composters and leave the final one to break down completely into humus.  

A bumper crop

Adam and Hayley decided to leave their compost for about a year so they could use it in a compost mix for growing potatoes.

With first-time use of a Green Johanna, it can take 6-8 months for compost to be ready for use. After that, depending on conditions, it’s usually 4-6 months. With regular cold composting it’s usually between 6 months to 2 years.

Great compost accelerator

The couple also used a bokashi bin alongside their Johanna.  The pre-compost that a bokashi bin produces makes an excellent compost accelerator, raising temperature and speeding up decomposition. Fermented bokashi mixture is usually quite wet so needs to be balanced with plenty of carbon-rich materials. The bokashi mixture will then break down in the composter. 

 ‘Bokashi has become a really useful part of our composting process,’ said Adam. ‘We put all our food waste straight into the bin and give it a few sprays of Bokashi spray, then once it’s full and has been left to ferment we transfer it to the Johanna.’

It usually takes them around one to two weeks to fill the Bokashi bin with their kitchen waste, which is usually vegetable scraps along with some beans. They then use their smaller kitchen caddy to take food waste to the Johanna while the Bokashi bin is ‘doing its thing’.

Food waste provides the compost mix with nitrogen-rich content, which must be balanced with shredded carbon-rich materials (dead leaves, twigs, branches, wood chips, paper waste) and regularly aerated to get oxygen into the pile.

The verdict on the Johanna:

With previous composting attempts, the couple had experienced slow breakdown of waste materials with hardly any compost produced.  

 ‘The Johanna is much better built and works faster at breaking down all the waste,’ said Adam.

The couple feel their efforts with the Johanna and Bokashi have paid off – not only are they recycling all their food and garden waste nature’s way, but they also get to make their own delicious home-grown spuds. What’s not to like? 

Spare Parts