Saving water in the garden
The garden is often the place where most household water is used and where most water can usually be saved. If you want your garden to look nice and enhance your house (most people do), you can achieve this effect without using a lot of water - even when it is dry.
A separate leaflet deals with plant selection for low water use gardens and there are books in the Byron Shire Library on this aspect of gardening.
When to apply water
Water should be applied only when necessary for plant health. In sandy soils this means that water should be applied at several days interval in the hottest weather. In loamy soils a good soaking every week in the hottest weather will probably be better for most mature plants than daily watering.
Sandy soils do not hold as much water as loamy soils and pass excess water easily below the plant root zone where it is wasted. So, apply only what is needed.
Apply water when the sun and wind are low. On a hot summer day, more than half of all the water poured onto gardens can be wasted through evaporation and run-off.
Applying a mulch to the soil will reduce the evaporation directly from the soil surface and will make watering more effective. Organic mulches (like compost, straw, dry manure and bark chips) will also assist the soil to develop a good structure so that water enters it more quickly and deeply. The soil will also hold more water with a higher organic content. Organic mulches generally have to be used on flat areas or incorporated in the soil around the wet season or they will float away when the rain comes.
Mulching also helps keep down weed growth; some inorganic mulches, like plastic weed matting, can stop them altogether. Talk to your local nursery about what is best for your plants.
How to water
The aim of watering is generally to apply water to the roots. Generally, if you apply water to the leaves, the first 2-3mm of water is caught on the leaves and evaporates quickly later. (Some fertilisers require foliar application of water containing the fertiliser but these require the use of a watering can or an approved hand-held device and are not much used in the garden. Some plants called Bromeliads also require watering from above).
Most lawns will survive and even look well without watering. You can encourage the lawn to be drought-resistant by:
- Cutting it no shorter than 20-30 mm from the soil (ie some leaf still in place).
- Aerating any compacted areas with a spike or fork to get the water to soak in better
- Fertilising lightly (and only occasionally) with a commercial lawn food.
- Leaving some or all of the clippings on the lawn - this reduces the need for fertiliser.
- Planting lawn varieties which are appropriate to the climate.
All watering systems are capable of abuse and will only save you time, energy, water, fertiliser and anything else if you adjust them correctly. The Australian Water Resources Council has indicated that most elaborate systems tend to be out of adjustment most of the time and should be avoided unless there is adequate attention to operation.
The simplest system for watering the garden is a hose with a tap timer. If you are going to water the garden and leave the hose unattended, a tap timer ought to be your minimum equipment.
Drip and Trickle systems
Drip and trickle watering systems are sometimes called local irrigation because they do not wet the soil surface much but apply the water directly where a plant needs it. These systems promote low water use.
Drip systems (in common with all irrigation systems) can only be connected by the householder to the tap and not to any other water supply connection. A qualified irrigation installer or a plumber is required to connect to the water mains or your own pipes.
Jet sprays are generally used to water the ground near the plant roots and do not spray water high in the air. They are therefore low water use devices. They are useful for fruit trees as they can wet a significant volume of soil for the tree (whereas a single dripper per tree does not). Jet sprays are also useful for flower beds.
Movable sprinklers (‘a Drag Hose’)
This system relies on you knowing where you want to water and how much you have previously watered other nearby areas. It looks like a simple system but unless you are watching carefully, it is easy to water areas which do not need it and leave out ones that do need it.
If you use ‘a drag hose’ system, then make notes on where you watered and get to know how hard you turn your sprinklers on to get the thrown you need. (Make sure you don not use a pressure which is too high or too low and waste a lot of water).
These should be installed by a professional to meet Council’s requirements for back-flow prevention. If you have a system of this type and it has an automatic controller, ensure that you adjust the controller so that whenever it rains, watering stops. You can get rain sensors for most systems which assist a little, although a better system is to use a tensiometer or gypsum block to turn the system off if the soil moisture is high. Better still, use manual operation.
All automatic systems require constant regular attention to make sure they are operating to peak efficiency. Back-flow prevention devices can go out of adjustment and waste water, so they should be inspected regularly.
Unless it is disinfected, tank water collected in town is not particularly healthy for drinking, but is useful for the garden.