Wicking bed under construction
 First
we made a trench. This should
be on the contour line and about 300mm deep.
This trench was made with the bucket on a small tractor.
There is no point in digging lower than the top soil as this will
bring up the sticky black clay.
The top soil can then be used to make the raised bed.
 The trench
must be level, an easy way is simply to fill with water and adjust any high
or low spots. In this case we
are going to use the wicking bed to irrigate a row of trees beside the bed,
so on the tree side the plastics will be made just below the previous soil
level and grass clipping uses to form the wick.
The other side will be left high so there is no waste of water.
 Lay
the plastic sheet in the trench. The sheet will almost certainly move during
filling so it is best to cut the plastics a little larger then simply fold
down the edges to the water level.
The pipe is laid in
place, here we are using PVC storm water pipe however almost any pipe will
do. Bamboo is good and cheap.
 The
pipe is slotted with and angle grinder.
The slots always go the bottom so the pipe does not fill up with
soil.
 The
trench is then filled with the organic filler; here we are using wood chips.
I this case we are using the wicking bed to irrigate the trees beside
the trench, but we will also place soil onto the wood chips to make a raised
bed. It is important to raise
the bed as if there is a long period of rain the trench will fill so there
must be a well drained zone above the water level.
 Here
we are growing legumes; they will be pruned to provide nutrients pulled up
from deep in the soil. Wood
chips take up a lot of nitrogen so using legumes or adding nitrogen is
important.
 This
is a mini wicking bed solely to irrigate the legumes.
A small trench is dug, lined with a plastics sheet and in the picture
is being filled with grass clippings to act as the wick.
In this case there is no pipe so the trench is not completely filled
so the there is a small furrow so the water can run along the surface.
Pipes are better but this is a dead cheap way of making
a simple and reliable irrigation system.
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18 Feb 2010
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