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

Chapter 2. Growing better lawns
Keeping a lawn lush, green and healthy in western Queensland is not easy but it can
be done. With careful use of fertilisers, soil amendments and watering, a lot of the
problems in lawns can be prevented.
Bore water
The quality of artesian bore water is one of the major problems in keeping a lawn
vigorous. Small amounts of sodium bicarbonate and sodium chloride in the water
accumulate in soils which are watered with the bore water, resulting in two conditions
which are undesirable for lawn growth:
The soil becomes hard and water penetration becomes very slow. This accentuates
the salt problem because the affected areas are watered little and often, with much
of the water lost by evaporation, and therefore wasted.
The soil becomes very alkaline. A pH level above 8.5 is commonly found. This
reduces plant growth and if very high (above 9.0) may cause unthriftiness and plant
death.
Soils affected in this way develop a black scale on the surface. The grass is often
yellow and grows poorly despite frequent watering.
Watering practices can reduce the build-up of salts at the surface by leaching out the
excess. The aim should be to minimise evaporation thus reducing waste of water and
avoiding the concentration of salts.
Watering in summer should not be done during the heat of the day. More than
half of the water from sprinklers is either lost to evaporation or used rapidly by
plants. This leaves only a little to wash through the soil to remove the harmful
salts from the root zone of the plants. Watering at night is best.
Watering should be as infrequently as possible with heavy applications at each
watering. Light watering encourages shallow rooting and excessive evaporation.
This will wet the soil to a considerable depth, thereby reducing evaporation and
reducing salt concentration in the root zone. Deep rooting is also encouraged
making the lawn less susceptible to periods without water; for example, when you
go on holidays.