25 Jun 2018

Making soil the superhero and hot and cold composting

From Nine To Noon, 10:07 am on 25 June 2018

Ben Elms a man passionate about the difference between dirt and soil.

“Dirt is weedy and unloved and doesn’t look very alive, soil is full of life, full of bacteria and fungi and earth worms. It’s just teeming with life, using compost turns dirt into soil a lifeless medium into one that’s alive.”

British-born Elms (also known as is Dr Compost) has lived on a lifestyle block in Central Otago for more than 20 years.

As Dr Compost, Elms teaches people how to garden and compost in partnership with Wanaka Wastebusters, a community organisation working towards zero-waste.

He also designs permaculture orchards, mentors people, runs workshops and writes for regional newspapers and gardening publications.

Elms is a gardener for all seasons.

He says the key to great yields is 'superhero' soil and for that you need compost.

There are various ways to make it.

On a larger section you can make compost bays with old pellets – which are generally free – but watch out for an ‘MB’ marking on some of them.

“Methyl bromide as a protective treatment of the pallet is still in practice. Avoid using any wooden pallets with the 'MB' stamp. Any with 'HT' (Heat Treated) are fine to use.”

Elms recently built three pallets bays at a Taieri Mouth community garden in just ten minutes.

“Six nails and we’d done it!”

Once you’ve got your bays there are two main ways to compost – hot and cold. Both need a mixture of green and brown material.

Greens are generally nitrogen-rich – grass clippings, manures and vege scraps – while browns are carbon-rich hay, straw, wood chips and sawdust.

The compost heap need about a third of the former and two thirds the latter combined with oxygen and water to work.

Composting hot and cold

Hot composting means you make your heap in one go.

It will make a lot of compost quite quickly but you need all the right ingredients to bake the cake, Elms says.  

"We’re going to fill one of those compost bins in one go.”

 The pile needs to be a metre high and a metre wide, he says.

“We’ve stockpiled wood chips and straw, maybe we’ve tidied up the garden, we’ve got loads of weeds, some grass clippings, we might have grabbed a few bags of manure form the side of the road.

"And then we’re going to build it all in one go, right now today."

The pile is made up of all the layers up in one go, alternating carbon and nitrogen materials.

"We might start with a nice layer of cabbage tree leaves to help that aeration, then some grass clippings, some straw, some manure, a layer of wood chips and so on – alternating those layers but at the same time remembering to add moisture.

“Water really is key to this recipe – and we’re baking a cake.”

If materials going in the heap are hydrophobic (such as straw) pre-soak them and make sure each layer is moist.

“I might have a sprinkler going while I build it, just hitting the heap.”

After a few days test for moisture.

“I come along and put my hand deep into the heap and grab a handful and give it a squeeze, you should see some moisture some drops coming through your fingers – that’s 50 percent moisture, that’s perfect.”

If the soil is too wet, oxygen won’t get in there so open up the centre. If it's too dry, add more moisture.

The same principles apply to cold composting, but the heap is built in layers over time and takes longer to mature, perhaps up to a year.

The Lasagne method

Another way to make soil quick, particularly if you’re gardening on exhausted or poor soil, is ‘Lasagne Gardening’, Elms says.

“It’s just like making a compost heap, you’re alternating different layers … a layer of straw, a layer of manure, a layer of wood chips a layer of grass clippings a bit of compost, you can quite quickly build it up.”

You can plant in a couple of weeks or make in the autumn and let it break down ready for spring.

The Bokashi method

For smaller properties, or as an additional source of soil-boosting good, stuff the Bokashi system has many keen adherents.

Bokashi uses a bucket system to pickle your waste, and you can put almost anything in it – all your food scraps in, including meat, fish and cooked bones.

A ‘magic’ powder is sprinkled over the scraps.

“The bucket slowly fills up and once it’s full you put it in a quiet place and it just starts pickling a couple of weeks later it still smells really good and you dig a hole or trench and you bury it directly into your vege garden or next to a fruit tree.

“Boom – you’ve just inoculated the soil with this biology and this huge organic matter.”

More super soil tips from Ben Elms

Mulch it

“We might get two or three days of rain rather than it raining once a week and it compacts the soil and leeches a lot of nutrients away. A mulch is a great way of protecting the surface of the soil – the soil doesn’t want to be naked, it wants its clothes on.”


“If you’ve got weeds growing around crops, why not pull them out and drop them right there?

Other times when you’ve got a real flush of weeds taking them to the compost is a fantastic way of harvesting – they’re great accumulators of minerals.

And dig up your docks.

“They’ve got these deep, deep roots and they are mining the soil deep down and bringing up all these amazing minerals."

A dash of ash

“You can compost it as long as no treated timbers were burned put some in the compost and save some for the tomatoes and potatoes.

“Every two or three weeks, I’ll grab some of that potash and sprinkle it around the top of the soil water it in and it enhances the flavour of those vegetables.”

Treat your section as its own ‘biosphere’

All organic matter – grass clippings, leaves, branches, deadheaded flowers – stay on the property and are returned to the soil.