Grow your own food

The garden diary

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May 2009

Soil carbon and climate change

In May we participated in a workshop about organic production methods. It was a real eye-opener for us! We had already used organic farming methods for many years and Permaculture had become second nature to us, BUT we had never realized that organic farming can make such a huge contribution to avoiding climate change. Andre Leu (chair, Organic Federation of Australia) has written a paper titled "Ameliorating the Effects of Climate Change with Soil Carbon" . In less scientific terms the message simply is: organic farming systems can sequester more green house gases than they emit and they can reverse the cause of climate change. This is done by increasing organic matter in the soil (higher carbon levels) which will lead to improved soil health and productivity. At the workshop Andre emphasized that conversion of the world's agriculture to organic farming methods would sequester enough carbon to eliminate the threat of climate change. We don't want to repeat what Andre writes and says, we just want to show what we are doing ourselves to increase the organic matter in our soil.

	Ground cover in the large orchard
	In autumn the ground cover is slashed

Ground cover in our orchards:

the beds in our established orchards are planted with ground covers (herbs and edible flowers, e.g. nasturtiums, calendula). These plants have a number of benefits:

- the soil is shaded in summer and keeps the moisture longer
- by growing the ground cover, we avoid the growth of unwanted weeds
- the plants give the soil their "carbon gift": they absorb CO2 from the air and deposit it into the soil (e.g. the root system)
- they attract bees

In late autumn we slash the ground cover and leave the plants on the beds. The chickens are now let into the orchard. They will break up the plants and scratch them into the soil. At the same time they will eat any insects they find.

The end result is a constant building up of soil carbon (humus) in our orchards:

Some of the benefits of humus (see Andre's article for details!):
- humus improves nutrient availability
- humus increases crop productivity (helps to neutralise the pH, makes minerals readily available, encourages growth of beneficial microbes)
- humus improves soil structure (creates spaces for air and water and encourages earthworms and beetles)
- humus improves rain absorption and decreases water run-off
- humus ameliorates the effects of climate change

A humus factory in the chook yard:

this is almost an accidental discovery! The netted area was bare and we placed hay bales in there to give the chickens "something to play with" and to create a dry layer on the ground. We always placed the bales on the high side of the yard and the chickens scratched them apart. Many months and many bales of hay later the result is incredible: our Welsummer rooster (right) stands on a 30cm high layer of dark soil enriched with composted chicken droppings and hay, perfect for the garden! The big heap of hay in the front of the left photo is the old litter from the chook house. Once it has composted it will go into the garden as well.

Edible chicken feed and compost:

Left: when this chook house is cleaned the old hay with the droppings goes onto the compost heap next to it. The composted material will then go straight into the berry orchard. The chickens currently free-range behind the chook house. Green manure grows in the small paddock on the left. Once the pig has dug up the paddock on the right some more, it will be planted with chicken feed, too. The chickens can have controlled access to any of these areas.

Right: an example of green manure sown seven weeks ago (next to the vegie garden).

Horse manure:

when we decided to get our miniature ponies and extensively use the manure in our gardens we had never heard about the Parisian market gardeners who grew fresh produce right in the city of Paris between 1850 and 1900. These maraîchers used horse manure for their market gardens and achieved incredible results. But with the introduction of motor cars these gardens disappeared.

Horse manure is an important part of our gardening systems. We use fresh manure straight from the paddock when we build up beds which we plan to plant at a later stage. We use composted manure directly on our garden beds. The pile of composted manure next to the horse shed is almost ready to use. The results are very good and the only drawback is that we don't have enough land to have even more ponies that could turn even more grass into the best organic fertilizer, and ultimately humus!

Pigs prepare the ground for planting:

rather than use a rotary hoe we let the pigs dig up the grass. Then we add a couple of bales of hay and after a few days the pigs have dug the hay into the soil. It's a simple way to get rid of the dense grass while adding carbon (and pig manure, of course!) to the soil. We won't plant green manure because we want to plant broad beans in a few weeks (see info below). This area will be fenced temporarily and return to grass after the beans are harvested in December/January

At the end of May the corn is slowly dying back (centre photo). It makes good food the pigs and the horses love it too!

broad beans sown in July: broad beans are usually sown in April and overwinter as small plants. The theory is that the cold weather makes them resistant to pests and diseases and that the harvest from broad beans sown in April is much better than from those sown in July. We tried it both ways and found that our soil contains so many grass seeds that the grass will grow back over winter when the beans don't grow much and that it will smother them. Beans sown in July will outgrow the grass very fast and we harvested at least twice as much from the July plantings. One real risk though is that the July plantings are probably not as hardy as the early ones and that we might loose them to severe frosts or pest or disease.

An extension to the small orchard

The small orchard is now fully netted and has room for 22 new fruit trees.

Poultry and gardens:

Every orchard has a chook house attached to it. The chooks scratch around in the orchard and get rid of pests. They produce manure; the old bedding from their houses goes onto a compost heap close to the orchard. The chickens in the small orchard are Minorcas. They are very rare in Australia

Every vegetable garden has a duck house attached to it. Ducks do not scratch up vegetables but are really good snail eaters! These are our Indian Runner ducks.

Late apples, cauliflowers and leek

Lady Williams

Rome Beauty

Sturmer

Left: purple cauliflower

Right: leek is planted in 15cm deep trenches which are slowly filled with soil up to the first leaf joint when the plants grow.

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Late autumn in southern Tasmania

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