Jul 30, 2010
Living Earth Compost – The Miracle Ingredient
Compost and Garden Mix. Questions and Answers from Living Earth. There are a lot of choices when it comes to growing mixes. Get the facts.
The key ingredient to the Garden Mix and that Black Gold that we proudly stock at Auckland Landscape Supplies is compost, locally brewed here in Auckland by Living Earth. It is a great story of recycling green waste that normally goes to our local landfills, into high quality growing mixes and you, the home gardener, get to benefit from this!
COMPOSTING AT LIVING EARTH AUCKLAND
Composting is nature’s way of recycling plants to replenish the soil and nourish new plant growth. In nature everything is recycled. As leaves, branches and other plant materials fall to the ground,, micro organisms (“bugs”) decompose them into dark, nutrient rich humus. We can copy nature’s way of recycling by making the garden waste from our homes, parks and businesses into compost.
In our human-made environment, we often upset nature’s recycling system by throwing out greenwaste as if it were normal rubbish. When dumped at the tip, greenwaste takes up greatly needed space. But there is another way...
Living Earth uses the same method of recycling garden waste that nature does. Here is how we do it.
Every day people greenwaste is delivered to our composting site at Puketutu Island so we can turn it into compost. This greenwaste is made up of grass clippings, small tree branches, leaves, weeds and shrubs. It is brought in to us by Auckland Landscape Supplies and garden bag collection companies.
All the greenwaste is put through our giant shredding machine. This tears the tree branches apart, exposing areas to make it easy for the bugs to feed on and break it down. These woody materials also give the compost pile some structure and helps oxygen move in and out so that the bugs have some air. After shredding, the greenwaste is put into long rows called windrows.
First a bit of background...
Some people say that making compost is like baking a cake. And they’re right! You have to use good ingredients, in the right amounts, mix together carefully and bake it for the correct time. The bugs that feed on the greenwaste need the right mix of brown stuff and green stuff to munch on. They also need air and water to live. Brown stuff is woody branches, dried leaves and sawdust and is high in carbon. Green stuff is grass, green leaves and plants and is high in nitrogen. Carbon provides the bugs with energy and the nitrogen gives them protein for their bodies. The best ‘diet’ for the bugs is 3 to 5 parts carbon (browns) and 1 part nitrogen (greens). This is what people mean when they talk about the carbon to nitrogen (C:N) ratio.
Now the bugs start to feed on the greenwaste and break it down, starting first with the sugars and starches found in plants. This feeding frenzy by the bugs causes a lot of heat to be built up in the windrow and this is how the compost gets hot. This heat also kills any weed seeds and diseases that may be present. To do this it takes a temperature of 55 0 Celsius for 3 days. Windrows usually reach 50-65 0 Celsius. After about 90 or 120 days the bugs have turned most of their food into dark rich earthy smelling compost.
The windrow pile is turned 3 times in the first 10 days, then at least another 8 times over 10 weeks. This mixing makes sure that cooler material on the outside of the row gets put into the middle, where it can get hot. At Living Earth we use large machines like front end loaders and excavators to turn our windrows.
BARK AND PUMICE FOR PLANTING MIXES
As well as making compost, Living Earth also produces a Garden Mix, a Lawn Mix and a Potting Mix. These are made up of the compost with added bark, pumice and fertilisers.
After it has been tested and OK’d by the lab, the windrow is passed through our screen, which separates out the fine compost from the sticks and branches. The large sticks and branches are ground up to make mulch.
Compost is screened into a shed where it is kept until it is needed for sales.
We have a laboratory on site at Living Earth so we can test our compost to make sure it is ready to be sold and that it has the right amount of nutrients in it. Then we keep checking it every week to make sure that everything is OK. We also regularly test our Garden mix, Lawn mix and Potting mix too.
Things that we test for are;
- nutrients – nitrate and ammonium, a form of nitrogen
- toxicity – done by a seed germination test
- put a plant in it and see how well it grows.
How much greenwaste do you get every year?
Living Earth receives approx 45 000T of greenwaste every year.
Do you need to add bugs to the compost?
No. All the bugs are naturally occurring on the plant material and in the environment.
What type of bugs break down compost?
Main ones are bacteria, fungi, actinomycetes (bacteria that are similar to fungi) and protozoa. Most are very small and can only been seen through a microscope.
Do you add anything to the compost piles?
Nothing is added to speed up the decomposition process. It is entirely natural. Just like humans, the bugs need food, water and oxygen to live and do their work. If these are present in the right amounts, the compost pile will break down OK.
Does it smell bad?
As long as the bugs have plenty of oxygen, there will be no bad smells. This is called aerobic, which means that the composting process has plenty of oxygen available to it. Bad smells happen when the oxygen supply runs out, and a different type of bug starts to grow – one that makes rotten egg smells.
How can you tell it’s ready?
It should be dark brown, smell earthy, and have a fine crumbly texture. This usually takes about 12-14 weeks. At Living Earth it has to pass tests for pH, nutrients (nitrate and ammonium) and be non toxic.
How do you use compost?
Compost or Black Gold is best dug into the soil, where it will help build good soil structure, retain moisture, suppress diseases, and provides plants with nutrients.
What is green waste and where does it come from?
It includes all garden waste produced at homes, in parks and urban gardens. Most of the green waste recycled at transfer stations around the city by home gardeners, landscapers and garden waste collection companies is sent to Puketutu Island to Living Earth’s Composting plant.
How is Living Earth Compost 100% weed-free?
Within a few days the heat generated in the green waste piles reaches a temperature of 55+ degrees. After 3 days at this temperature the seeds are killed off and will not germinate.
What quality standards does Living Earth Compost meet?
Living Earth Compost meets NZ4454, a New Zealand standard that ensures that compost is properly decomposed, free of pathogens and safe to be applied back into your soil. In addition, Living Earth has its own in-house laboratory for testing each batch of compost, plus undertaking growth trials of the compost, so that you, the gardener, can be assured of premium quality when growing your plants.
So it’s good for my garden, but how does it benefit all of Auckland?
Living Earth composts around 40,000 tonnes of green waste each year – that’s recyclable organic matter that doesn’t go into Auckland’s landfills and start to emit Greenhouse gases. And as it’s made locally, it’s not travelling a lot of kilometers in its lifetime, so it doesn’t use up enormous amounts of diesel getting to you!
Written by Elena Izaguirre (Technical Manager) Living Earth and Heather Tait (Sales and Marketing Manager)