Composting for Sustainable Soil & Plant Health

There are several methods that you can employ to decompose your organic waste into valuable compost. These include using compost bins, free standing heaps, worm farms and bokashi.

Organic matter for composting

Autumn is nature’s time for returning organic matter to the soil and it’s also a great time to make compost. This is why the Tasman District Council made May the "Kickstart Compost Month". TDC wanted to encourage the public to start composting because it’s good for the environment. Benefits include reduced organic waste entering landfill, which reduces the leaching of potentially toxic waste into waterways. Using compost in the garden improves soil quality by increasing soil carbon and therefore water holding capacity, nutrient availability, drainage and reduces soil erosion.

To encourage the public to start composting, Tasman District Council made May the "Kickstart Compost Month."

Composting Systems

There are several methods that you can employ to decompose your organic waste into valuable compost. These include using compost bins, free standing heaps, worm farms and bokashi.

Each system has its benefits to the user and depends on your circumstance. For example, if you have a large garden then you’re likely to have an abundance of organic material that needs decomposing and so a larger compost system like the Kiwi three bin method would be ideal. If however you have a small suburban section then a work farm maybe better for you. There’s a system that will work best for you its just a matter of working out which is best.

Compost for fruit and vegetables

Because fruits (and other perennials) are perennial plants they benefit more from having persistent organic matter covering the soil surface. The best materials to use for making fruit compost are a combination of woody materials, manure(s) and greens such as grass clippings, comfrey and food scraps. Woody material like branches are best put through a chipper to increase the surface area of the material to speed decomposition. Mix all these materials together and leave until fungi sprout from the pile.

Vegetable compost is best made from soft carbon material like crop residues, hay, straw with green material like weeds, food scraps and manure too. The soft carbon breaks down much faster than woody carbon producing compost that supplies more available nutrients to hungry vegetables as compared with woody compost that is more slow release. The use of too much woody carbon in vegetable gardens removes nutrients like nitrogen by bacteria and other soil organisms responsible for decomposing this organic matter.

Tips to make composting better

1. Establish a good site for your compost. Best in sunny position for improved decomposition. Also close to a hose as water is an integral part of making good compost. Also having easy access to bring in outside resources helps too. If the position is up hill of the vegetable garden for example then any leached nutrients will also feed the garden.

2. Select a suitable container is best for new-bees to compost making. Pallets are cheap and easy to set up. Smaller recycled plastic bins are more compact but typically don’t get hot enough to kill weed seeds and pathogens (discount applicable if sourced from one of the designated stockists).

3. Use a diverse range of organic materials. One of the reasons compost is so good is that it also supplies a bounty of micro and macro organisms to the soil enhancing the soils fertility. The more diverse the materials used to create compost the more diverse a range of these beneficial organisms you’ll have. Also its good to inoculate the compost with materials high in beneficial organisms. This includes natural yoghurt, soil on weeds or from a healthy pasture, old compost, manure and organic litter from forests and hedgerows. Research by Douds et al (2007) shows that adding some soil rich in Arbuscular mycorrhizal (AM) fungi into composts enhances the uptake of immobile mineral nutrients like phosphorus. These AM fungi form symbiotic relationships with host plants improving their yield.

4. Turning a heap will enhance the breakdown process thus speeding up the time compost is mature and ready for use. It’s important for vegetables that compost is well decomposed for greatest benefit to the soil and crops.

5. Cover the heap to minimize the rain that will leach nutrients away.

If you’re interested but unsure how to compost your food scraps etc then you could do the free compost workshop offered by the Sustainable Living Centre at the Community Gardens a few times a year. Register to ensure your place with our local Environmental Education Officer Claire Webster at Claire.Webster@tasman.govt.nz.

Like this blog? Please leave a comment below and tell us what you learned or what you would like more info on. Sign up for more.