It's a dirt cheap way to make a lasting difference

"It's looking much better," she says. "It's a good mixture, although it'll still be a while before you can put it on the garden."

Voluntary work usually conjures up images of manning the tills in charity shops, or helping with the local Brownies. But for Kirsty, 26, from Haymarket, it involves poking around in other people's compost heaps.

It's not an odd obsession but a vital part of Changeworks, an environmental project which aims to cut down the waste we produce. We've all heard the dismal statistics that we throw out about a third of the food we buy, and about 30 per cent of the contents of the average household bin is organic waste, such as used tea bags or vegetable peelings, which can be turned into compost.

Kirsty, a "master composter", and project co-ordinator Kathleen Kirkness are on a mission to get Edinburgh folk composting leftover food. As well as cutting down waste, it's a cheap and easy way to produce garden fertiliser. Homemade compost is actually better for the garden than shop-bought, as it is a great source of biodiversity and has not been sterilised.

The encouraging message is that it doesn't matter if you live in a tiny flat or have never picked up a trowel, help is at hand.

Today, they are chatting to Marianne Ferguson Rice, 85, a retired teacher and social worker from Stockbridge, who has been composting for several years. But when she bought a brand new bin 18 months ago, something seemed to go wrong.

"It just wasn't doing its job," she says. "The stuff in the bin wasn't decomposing. I put all my kitchen waste in; I'm a vegetarian, so I've quite a lot of vegetable and fruit waste.

"The first person who came out said it looked very wet, so I started putting in more cardboard. Then they realised I should move the bin, as it was partly sitting on concrete. It was meant to have worms in it but they couldn't get in!"

Simply moving her compost bin has transformed Marianne's heap from a mass of slimy waste to nutrient-rich fertiliser. Kathleen says it is important to support people, or they are likely to give up when things go wrong.

She says: "People can call us if they're having any problems and we can come and offer advice. A lot of people are unsure what you can compost – for example, if you put cooked food in, you could get a problem with vermin.

"Most people know about the peelings and food waste but you can compost dry stuff, such as cardboard, too. It's important to get the right balance. You can buy worms on the internet or in fishing shops but if you've got the right mixture, they should come in."

Their Master Composter programme trains volunteers to offer advice and support in their communities. There are now 48 of them in the city, each giving up a few hours a month to help out.

Kirsty, an environmental biology graduate from Napier University, joined after several months with the city council's Eco-Schools programme. She found she was often asked questions about composting and decided she needed to find out more.

She has always been passionate about the environment and a compost bin was part of her family life when she was growing up. Now she finds herself in gardens of all sizes, dealing with problems from mushy waste to bins infested with rats. She also gives talks and helps out at events around the city.

She says: "I wasn't confident enough to give them advice at first, so I thought I'd do the master composting course. A lot of the problems are to do with people not putting the right mixture in. It can be too wet and slimy, or too dry. Lots of people don't know the range of material you can compost."

She is keen to encourage more people to try. Compost bins can be bought through the city council for 8, and for those who prefer to do it themselves, a compost bin can be built from scrap wood.

Kirsty says: "A lot of people think they can't do it if they live in a flat but there are lots of things you can do. If you've got a shared garden, you could think about having a shared compost bin.

"There are lots of community gardens where you can help out, or you could try and have an allotment. If you don't have the time, then why not go next door and see if your neighbours could use your compost?"

Many schools have also introduced wormeries. Like miniature compost heaps, they can be kept indoors and are a great educational tool. They produce a very concentrated liquid, which Kathleen says resembles "Baby Bio", and is perfect for feeding house plants.

"You have to be quite dark green before you get to the stage of having a wormery in your flat!" Kathleen laughs. "But you'd be surprised how many people have them in their homes.

"Composting has really become quite trendy now, you get people of all ages doing it. There's a huge interest in growing your own at the moment, and making your own compost is part of it."

The ideal compost bin should include roughly half "green waste" – such as food scraps – and "half brown waste" – drier items such as cardboard.

Materials such as egg shells, rabbit litter and woolly jumpers can all be thrown into the mix. Some gardeners even swear by adding human urine, as it helps activate the composting process.

Cooked food should be avoided, unless you buy a purpose-built "green cone" or "food-waste digester" for the garden.

The key ingredients are heat, air, moisture and materials. It's best to put the bin in a sunny spot in the garden. Turning the compost adds oxygen and ensures it doesn't get too packed down.

After nine months to a year, the reward should be a clean, soil-like material which can be spread on the garden. The pile will have reduced to about half its original size with an earthy smell. This can be used as a potting compost, or simply spread on top of flower and vegetable beds.

"It's very rewarding and can save you a lot of money," Kathleen says. "Now would be the perfect time to start as we're coming into spring and the ground is getting less hard. You can keep adding to it throughout the year."

Anyone interested in composting can contact Changeworks for free advice. Call 0131-555 4010, or e-mail master [email protected]

VOLUNTEERING FOR CHANGE

CHANGEWORKS Resources for Life Ltd began in June 2006 – its predecessor was Lothian & Edinburgh Environmental Partnership (LEEP).

The name change was made to reflect the group's wider presence than just in Lothian and Edinburgh.

Changeworks is taking part in UK's biggest voluntary sector event, The Gathering, which is being backed by the Evening News. It is being held on February 18 and 19 at Edinburgh International Conference Centre, when along with the Energy Savings Trust, Changeworks will be displaying the "eco-car".

Changeworks is a member of the Scottish Council for Voluntary Organisations, which is organising The Gathering.

For more information on Changeworks, contact 0131-555 4010 or [email protected] or visit www.changeworks.org.uk. For more information on The Gathering, visit www.scvo.org.uk/thegathering.