Composting, Worm Farms and Bokashi 

This page gives you details of how to re-use organic waste using different techniques and details of a subsidy for purchase.

Composting 

Plant and animal material can be naturally broken down by worms and soil bacteria and fungi. Compost is a natural plant food, soil conditioner and mulch.

Why Compost?

It will enhance your garden. Compost:

  • encourages plant growth;
  • improves drainage in heavy clay soil and conserves water in light sandy soil;
  • keeps the soil cooler in summer, warmer in winter;
  • increases aeration in compacted soil.

 It saves you money because it:

  • halves rubbish removal costs;
  • reduces the need to water the garden;
  • reduces the need for artificial fertilisers.

How to Compost

All you need to do is gather together waste organic materials and mix them in a compost bin or heap. Worms and other critters will do the rest. It saves the environment.

Reducing rubbish and your reliance on water and artificial fertilisers is a simple way to help the environment. When everything ends up in the landfill we are throwing away precious resources and creating potential problems. Some of these problems are expensive such as long-term monitoring of filled landfills.

Compost Subsidy Vouchers

Tasman District Council encourages home composting. It offers a subsidy on the purchase of compost bins, bokashi and worm farms as well as worms from any of the listed retailers. To receive the subsidy, download and print off the voucher, or call into any Tasman District Council office for a compost subsidy voucher, or ask the retailer for the voucher before making your purchase.

What to Compost

Materials you can compost are:

  • vegetable and fruit scraps, tea leaves and coffee grounds
  • vacuum cleaner dust and untreated wood ash
  • old potting mix, leaves, garden and lawn clippings, weeds (if they have not gone to seed)
  • sawdust, straw, animal manures, and seaweed.

Materials not to compost are:

  • meat, fish, fats or cooking/salad oils (these may create odour and fly problems)
  • wood, bones, diseased plant material
  • plant foliage with residues of chemical sprays, especially hormone type weedkillers
  • oxalis, and other problem weeds such as live twitch, convolvulus, docks and dandelion.

Siting Your Bin

You can either buy a bin or make an enclosure yourself. Locate your compost bin in a sheltered area, preferably not in full sun. The compost heap should sit directly on the soil.

Setting Up the Bin

1. Before positioning the bin, fork over the soil on the site to aid drainage and encourage earthworms into the heap.

2. Start the heap by placing a 10-15cm layer of coarse twiggy materials (coarse partly decomposed materials from a previous heap may be used) at the bottom of the bin to ensure good drainage and entry of air.

3. Add:

  • kitchen and garden waste
  • manure, soil, blood and bone or a compost activator.

4. If the compost heap is regularly turned it will be ready in 3-4 months. If the compost is not turned allow 9-12 months for the heap to mature.

Tips

  • Chopping or shredding coarse materials into small pieces before composting speeds up the process.
  • Coarse and fine material should be well mixed.
  • Dampen your heap regularly in summer to maintain the consistency of a squeezed out sponge.
  • Decomposition is faster in the warm summer months because the rate is dependent on temperature.
  • Compost is mature when it has darkened and is a crumbly soil like material. If used too soon it may borrow nitrogen from the soil as it breaks down. This will limit the nitrogen available to growing plants.
  • The heap needs to be large enough to maintain heat for microbiological activity. A cubic metre or slightly larger is sufficient size.

Using Compost

Mix into the soil or use it as a mulch on the soil surface. Either way it will result in improved soil stability, increased soil fertility and a boom in the earthworm population.

  • Real benefits occur if compost amounts to more than 25 percent of topsoil volume. Compost breaks down in the soil and needs to be replenished regularly. There can never be too much compost.
  • Partly decayed or unfinished compost makes the best mulch for suppressing weeds, but it needs to be at least 10cm deep to be effective. Do not use partly decayed compost in the subsoil or at depths greater than 15cm or hydrogen sulphide gas - which is toxic to plant roots - may be released.
  • To avoid fungal decay, do not pile compost up against tree trunks or plant stems.
  • If you have added lime to your compost do not use it around azaleas, camellias, rhododendrons, pieris, ericas and acid loving natives.
  • When planting trees and shrubs do not put compost into the bottom of the hole.
  • To avoid disturbing the roots of established trees and shrubs it is best to use compost as a surface mulch rather than dig it in. In time earthworms will drag it down and mix it with the soil without harming plant roots.

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Bokashi 

The Bokashi two-bucket system consists of a few simple elements. Two buckets are required, with one nested on top of the other. The top bucket has a tight fitting lid and holes in its base to drain to the lower bucket. In addition there is a bag of Compost-Zing made from wheat-bran and untreated saw dust that has been mixed with molasses and water and Effective Micro-organisms.

You can make your own system as long as it is air tight. Old paint buckets that have been cleaned out work well. Drill holes in the base of the top bucket and sit inside the other one. A good air-tight seal is very important.

The Benefits

The benefit of this system is that you can add products such as meat and fish, which are discouraged in the usual compost due to vermin and odours. No outdoor space is required for the collection of the material as fermentation takes place in the bucket, which makes it ideal for businesses, small houses, apartments and schools.

Once the bucket has been filled it must be left closed for up to two weeks. Then it can be added into your normal compost or it can be dug directly into your garden. Due to the acidity of the material it is not advisable to place it in direct contact with roots. It will neutralise within 7-10 days. No outdoor space is required as fermentation takes place in the bucket, which makes it ideal for businesses, small houses, apartments and schools.

The liquid that drips through to the bottom bucket can be drained off and 1 teaspoon mixed with five litres of water to produce a plant fertilizer.

Buckets can be kept indoors as the smell is inoffensive. It keeps food waste out of the landfill and it is good for your plants adding beneficial vitamins to the soil.

Larger scale systems can be used in businesses.

Foods You Can Include

All food waste which is well drained which includes:

  • fresh fruit and vegetables
  • prepared foods
  • cooked and uncooked meat and fish
  • cheese and eggs, coffee grinds, tea bags
  • wilted flowers

Foods You Cannot Include

  • liquids such as milk, orange juice and oils
  • paper and plastic wrap and meat bones
  • shells from seafood

Buckets can be kept indoors as the smell is inoffensive. It keeps food waste out of the landfill and it is good for your plants adding beneficial vitamins to the soil.

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Worm Farming 

Worm composting is a simple way to recycle your organic kitchen waste, and return valuable nutrients to your garden. Worm farms can take purely kitchen waste without needing garden waste mixed with it.

Other advantages of worm farms are the rich vermicast compost they produce, and their ability to digest paper.

In a two person household 1000 red or tiger worms are enough to digest food scraps. The castings take about seven weeks to be ready to use on the garden, which is quicker than compost bins. Earthworms from the garden can also be used in a worm bin but don't process food as quickly.

Vouchers

Tasman District Council encourages residents to use worm bins instead of throwing scraps in the rubbish because it saves space in the landfill and improves the environment. For these reasons Tasman District Council provides a subsidy when residents buy worm farms and worms from participating retailers. Please download and print the voucher or call in to the Council office for a compost subsidy coupon or request a voucher from the retailer, before purchasing worms or a worm farm.

How to Make a Worm Bin

  1. Buy, recycle or make a suitable container (wood, plastic or metal).
  2. Drill or punch a few holes in the bottom of the container for aeration and drainage.
  3. Place moist bedding (shredded newspaper or similar) in the worm bin, plus one or two handfuls of coarse sand or top soil.
  4. Bins should be raised up on bricks or wooden blocks to aid air circulation and drainage. By placing a plastic tray underneath to capture excess liquid, you can obtain an excellent liquid plant fertiliser - use diluted at the rate of 1 part liquid to 10 parts water.
  5. Add tiger and/or red worms (1000 or so). Tiger worms and red worms can eat as much as their own weight per day. That means that 1000 worms can eat about 400g per day of food waste.
  6. Bury kitchen waste (vegetable and fruit scraps) just below the surface of the bedding preferably spread around the bin. The worm population will steadily increase. In ideal conditions they can double their numbers every 40 or so days.
  7. Cover with sacking or a loose fitting lid that will keep the material from drying out and provide a dark environment for the worms.
  8. Additional fresh bedding should be added at least every two months.
  9. Harvest compost (worm castings) after 3 to 4 months and feed your plants.
  10. Top up bin with fresh bedding to replace the compost removed.

Feeding

Worms will eat most vegetable and fruit scraps, shredded paper, tea bags, tea leaves, coffee grounds, crushed egg shells, bread scraps, cereal, cottage cheese, plate scrapings and biscuit crumbs.

Dairy products may also be used, but feed in moderation. Meat and fish scraps may also be used but are not recommended until you are familiar with worm composting.

Foods to avoid are citrus, onions, garlic, garden waste and grass clippings (garden waste is best dealt with by conventional composting methods), fats, cooking oils and oily foods (these create slimy conditions, odour and fly problems) and chicken manure.

Tips

  1. Add food regularly rather than in large quantities.
  2. Chopping or mincing food scraps before feeding speeds up the composting process.
  3. Crushed egg shells provide sufficient calcium to stimulate earthworm reproduction and activity.
  4. Worms don't like an acid environment so a monthly sprinkling of dolomite or garden lime is desirable.
  5. Semi-mature compost and aged manure provide a source of decomposer micro-organisms which help to soften the food for the worms, as well as providing additional food.
  6. If bins are outdoors, protect from full sun in summer, and keep well insulated with packaging material, carpet or something similar, in winter.

Using the Worm Compost

Finished worm compost is nutrient rich, so it is excellent for topdressing container plants and as an ingredient in potting mixes. It can also be used in the garden to condition the soil every time you plant (a handful mixed into the soil when transplanting vegetables etc gives plants a good start). Use in small amounts.

Compost used as part of a potting mix or as a topdressing around potted plants should not contain worms as they tend to upset the functioning of the potting mix.

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Participating Retailers

Compost/Worm Bin Retailers

Golden Bay Hammer Hardware

  • 4A Commercial Street, Takaka
  • Ph 03 525 7265

The Warehouse Ltd

  • 270 High Street, Motueka
  • Ph 03 528 1079

Nelson Environment Centre

Julie’s Compost Shop

Bunnings Warehouse

  • 76 Saxton Road, Nelson
  • Ph 03 547 1640

Mitre 10 Mega

  • 99 Quarantine Road, Nelson
  • Ph 03 547 0747

Worm Providers

Farmer Bob’s Organic Worm Farm

  • Richmond
  • Ph 03 544 6716

Julie’s Compost Shop

Bokashi Retailers

Julie’s Compost Shop

Bokashi Boost

Bunnings Warehouse

  • 76 Saxton Road, Nelson
  • Ph 03 547 1640

Mitre 10 Mega

  • 99 Quarantine Road, Nelson
  • Ph 03 547 0747

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