western-queensland-gardening-guide.pdf - South West NRM

Plant into deep soil moisture
Good quantities of moisture at 30 to 90 cm depth under planting sites will increase
tree survival and growth rates considerably. Fallowing land and waiting for natural
rainfall to soak the soil is one way to achieve this. If there is no rain, pre-soak the
planting holes with 20 to 40 litres of water. In heavy soil, soakage may take a
number of hours.
Build water traps and mounds
Water traps, which may be small dish-shaped depressions around the tree or larger
diversion banks to catch run-off water for the tree (see Figure 13), can be very helpful
in increasing the benefit of rainfall for the trees. They can also help when watering
because larger volumes of water can be poured on the tree without it running away.
Mulching will help reduce evaporation
Evaporation of water from the soil surface can have two undesirable effects on
planted trees:
it can be a major cause of water loss from the soil profile, thus reducing the
amount of water available for the trees
in situations where poor quality water is used, or where the soil is high in salts
and minerals, evaporation can actually cause concentration of toxic levels of salts
in the tree root zone. This can lead to poor growth and possibly death of young
trees.
Mulching exposed soil around young trees will help in reducing evaporation and
help provide maximum benefit to the tree from any rainfall or additional watering.
Mulching around trees will also help to keep soil temperatures even and provide
shelter for beneficial soil organisms like worms, fungi and small insects. Organic
mulches such as straw, leaf mould, bark chips or rotted manure are highly desirable
both for moisture retention and protection from mineral build up. Rocks, gravel or
woven plastic matting can also be used as mulch around young trees.
Plan a watering stratem
The most desirable outcome of watering is to get trees to a stage where they can
survive in the natural conditions without help.
In situations where water is very limited and of poor quality it is advisable to
concentrate on heavy but infrequent watering which should be encouraged to soak
in close to the tree and deep into the soil. Planting into pre-soaked holes with follow
up watering at two week to monthly intervals for the first few months, falling back
to six weekly to bi-monthly, should be adequate to get drought-hardy trees
established. Watering should be reasonably heavy, 20 to 40 litres per tree. Provided
water traps and mulches are used, these should be adequate to allow good tree root
development. After the first six months trees should only be watered on an "as
needed" basis unless extra water is available. If larger volumes of water are
available, watering should be heavier but not more frequent. The process of
infrequent soil wetting and drying will encourage the young tree to develop a root
system more tolerant of natural conditions.