Things to know about lawn irrigation
How much should I water my lawn?
Apply the Goldilocks principle: not too much, not too little… but just the right amount.
Too much water
Overwatering reduces oxygen, causes compaction and can let valuable nitrogen be released as gas. This will stunt lawn growth, make it look pale, and can create dead patches.
It can also bring on fungal problems. Flooding your lawn is like eating too much, it will make the lawn sick, and you won’t be able to use a sodden lawn
Don’t just water your lawn when it looks pale or is yellowing. It needs the right amount of consistent watering, just like an athlete needs consistent hydration.
If your lawn gets past ‘wilting point’ it will not recover. This means there is so little water in the soil that it can’t recover to what it once was, even if you water it.
Under-watering slows the supply of valuable moisture and nutrients, essential for plant health. So, what is the right amount…?
How much you I should water my lawn?
To get watering right, you need to consider the soil your lawn is growing in. It sounds very techo but simply do this. find some average soil that your turf is growing on:
If the soil seems to be gritty and does not form peds (or small clumps of soil), it’s probably a sandy soil.
Sandy soils need more watering than others. You may also need some added organic material like well-rotted manures (say 20%) .
Don't forget, you will need to water periodically in winter (winter can be dry too).
Water moderately in spring and autumn, and you might need heavier watering in the heat of summer. This is because the water percolates (drains) through the soil easily and goes into the subsoil quickly and away from the root zone of the grass in sandy soils.
Sandy loam soil
If you rub the soil between your fingers and it leaves a slight stain on them, you probably have a sandy loam.
This is good for turf growth as it has enough sand to keep oxygen in the soil and enough clay particles to supply nutrient. It will only need moderate watering through winter, spring and summer as the clay particles can hold quite a bit of water.
If the soil peds are about the size of a 5 cent piece you may have a clay loam.
With this soil type, there may be more clay than loam. Ease off watering in winter and autumn when it rains, as the soil will hold more water than the sandy loam.
Light to moderate watering can be used in spring but water moderately in summer, especially with excessive heat.
Now you have investigated the soil under your lawn, the next step is to check out the evapotranspiration rate for your district.
What is evapotranspiration?
Plants have a unique evaporation system. It’s called evapotranspiration.
Simply put, the moisture is drawn up through the roots and out through the leaves, a bit like a vacuum.
The evaporation rate has an impact on the amount of water lost through the plant into the atmosphere.
The aim of irrigating is to re-charge the soil with the moisture plants need.
How to check the evapotranspiration rate in your area
Daily records of evapotranspiration in Australia are available from the Bureau of Meteorology (B.O.M.), or you can look up your national weather bureau.
How do you use this information?
Check the rates of loss for your approximate area.
Set your irrigation to return this water to maintain ‘Field Capacity’ (Field Capacity is the water held in the soil after gravity moves excess moisture through the layers).
Check seasonal changes and adjust the frequency of your watering cycles.
Alternatively, there are smart watering systems connected to the B.O.M. that will water according to B.O.M data. Some programmed watering devices receive weather data via a Wi-Fi hub. Watering occurs when it is needed.
The Goldilocks principle of watering just the right, is the best way to keep your lawn healthy and turgid (holding usable water).
Choosing irrigation for your lawn
Water needs to be delivered to every part of your lawn so coverage is important.
Manual sprinklers provide inconsistent output but can cover your lawn if arranged correctly. There are many types. Here are just a couple.
The soaker hose:
The soaker hose is a long-time favourite supplying water through a hose punctured at equal intervals. The spray is light, but outputs volume over time wetting a strip up to 4 metres wide.
It is particularly good when setting lawn seed as its soft spray does not wash out the seed (unless it’s used for too long).
When setting seed, the idea is water softly but more often until the seed germinates and takes hold.
Wobble top sprinklers:
Sprinklers like the Australian made
Wobble –Tee™ sprinkler delivers coverage to 8m in diameter with consistent droplets like light soaking rain.
Sprinklers like this provide even coverage, but like all manual sprinklers, you have to move them to cover the turf completely
An irrigation specialist can design and install a system that is automated and responsive to weather conditions.
Traditional pop-up sprinklers water above ground in a wetting pattern designed to water the whole lawn surface.
They are controlled with an electronic programming system that uses electricity. Some may use solar.
Watering above ground can mean wastage in run-off and evaporation. Additionally, the lawn surface may be wet when you need to use it, restrict access to the lawn when it’s operating and in most cases does not comply with water restrictions.
An alternative is a sub-irrigation system that goes under your lawn like Ezi Mat.
Ezi Mat waters evenly across the roots zone, does not pool or waste water.
It uses less water than above ground systems and complies with Stage 2 water restrictions due to its short watering cycles.
EziMat can be linked to the B.O.M. by an App that waters the lawn when needed and uses programming powered by a battery without a complex powered system.
The choice is yours but for a healthy lawn you will need a consistent supply of moisture to maintain healthy plant processes.
Seek the advice of an irrigation or product specialist or your landscaper to conserve your lawn asset. They can assist you to decide on an irrigation system to suit your requirements.