Cultivating News
From "Maple Street Co-op News", Apr/May 2005
Water Efficient Gardening and Living
by Mary Meadows
Have you noticed that when we move from an environment where a water
authority supplies water, and the water just seems to flow out of the
tap, to an environment where we have to "catch" our own water,
we very quickly develop an awareness of conservation of this precious
resource?
An article by Katrina Strickland in "The Weekend Australian"
(26 March) highlighted the lack of logic in some of our perceptions
of value. Katrina's research showed that users in Sydney pay 1 cent
for every 10
litres of high-quality drinking water delivered 24/7, compared to $1.60
per litre for bottled water. She reported that sales of bottled water
are growing at 15 per cent per year.
We currently spend $525 million a year on a product advertised as "pure"
and drawn from "pristine sources" (give me tank water any
day!), and yet governments have been reluctant to increase the cost
of tap-supplied water for fear of political backlash.
"The Weekend Australian" also commissioned experts from the
University of Technology in Sydney to undertake a chemical analysis
of tap and bottled water. Dr Grant Hose, a research fellow in ecotoxicology
who oversaw the analysis, said the results showed that tap water is
as healthy for you as bottled water and that mineral levels are not
significantly elevated in the bottled waters.
Our tanks at home in Conondale are full, given that we have a good-sized
roof expanse for collection; but with the limited rainfall we've had
this summer, the soil is very dry and three of our small dams are empty.
The other dam is a quarter full, only because it is in a better catchment
area. This lack of water with which to irrigate has caused me to be
very conscious of what plants are surviving and what planting I will
do in the future.
Plants and trees that survive in the dry
Before I go into some characteristics of plants that use water more
efficiently, here are some plants and trees that have weathered the
dry at my place: Leptospermum polygalifolium (wild may), Austromyrtus
dulcis (midyim), Backhousia citriodora (lemon-scented
myrtle), Backhousia anisata (aniseed myrtle), Citrus australis
(native lime), Cordyline stricta (slender palm lily), Diploglottis
campbellii (small-leaved tamarind), Hymenosporum flavum
(native frangipani), Lomandra species (river reed), Podocarpus elatus
(brown pine), Syzygium australe (brush cherry), Syzygium
luehmannii (riberry), Toona australis (red cedar), Waterhousea
floribunda (weeping lilly-pilly) and Zingiber species (turmeric,
ginger, galangal, etc.).
Drought-resistant plants avoid the loss of water through evaporation
by having a light foliage colour, a thick waxy cuticle or hard leaves,
by closing the stomata during the day and/or by having leaves that are
small (as in cacti).
Plants avoid drought by having a bulbous or rhizomatous rootstock, reducing
competition by growing at remote distances from neighbouring plants,
or developing an extensive root system. As water available
in the soil is mostly taken up by fine root hairs, there are advantages
in having an extensive root system. A large percentage of water passes
into the atmosphere through the leaves' stomata (leaf surface openings).
A thickening of cell walls reduces water loss and this, combined with
the presence of a waxlike material, helps water conservation.
Other plants may have scales or fine hair. This layer of leaf hairs
allows the humidity of the air immediately above the leaf surface to
remain high so that the plant no longer releases water into the atmosphere.
Scales achieve a similar effect, reducing airflow over the leaf surface.
Some plants are able to absorb water (dew) into their leaves; however,
leaves with a waxy cuticle often have a V-shaped cross-section which
provides a valley structure to carry water down to the base of the plant.
Techniques for reducing evaporation
Protection from the intense heat and light of the sun can be provided
by tree canopy. This canopy may not be good for growing grass; however,
ground covers such as thyme or gravel can look just as attractive.
And while mulch may not be the most appealing-looking solution as ground
cover, it modifies soil temperature (but don't use black plastic). Mulches
reduce evaporation of water from the soil surface by as much as 60 per
cent. Plants, especially those that shade the soil surface, can also
act as a living mulch.
They can act as a windbreak and reduce evaporation, even if they take
water from the soil and transpire it into the atmosphere.
Give some thought to designing watercourses that are sheltered by overhanging
foliage/canopy and lead to small ponds. The ponds may dry out in summer,
but they are great for birds and other wildlife.
.
If you use a sprinkler system to water your garden and need to check
the coverage, place empty food cans in a regular grid around your system;
then check the volume collected in each can and adjust the system to
correct any imbalance. Plants grouped together should have similar water
demands.
.
[From "Maple Street Co-op News", Apr/May 2005; published by
The Maple Street Co-operative Society Ltd, 37 Maple Street, Maleny,
Qld 4552, Australia, tel (07) 5494 2088, email maplest.co-op@serv.net.au,
website http://www.maplestreetco-op.com.au]