WATERWISE GARDEN & IRRIGATION TRAINING

Transcription

1 WATERWISE GARDEN & IRRIGATION TRAINING Local Government Authorities Manual developed and written for the Water Corporation by John Colwill, with specialised irrigation input from Steve Peck. The section on Waterwise Irrigation and the Irrigation Efficiency Guidelines was developed and written for the Water Corporation by Colin Campbell. In partnership with

2 The views expressed in this document are not necessarily the views of the ICLEI Local Governments for Sustainability (ICLEI), and ICLEI does not accept responsibility in respect to any information or advice given in relation to, or as a consequence of, anything contained herein.

3 Waterwise Council Program The Department of Water, Water Corporation and ICLEI Local Governments for Sustainability Oceania, have developed a Waterwise Local Council Program to promote sound water management and water use efficiency in local government. The aim of the Waterwise Local Council Program is to help local governments in Western Australia adhere to the Government s water efficiency measures and further encourage councils efforts to improve water use management at both corporate and community levels. Waterwise Councils will be positioned as the very best of today s sustainable water managers. To maintain the Waterwise recognition status a local government authority has to: 1. Continue to commit to and progress through the Waterwise criteria and the ICLEI Water Campaign modules and milestones until completed. If a council is not participating in the Water Campaign equivalent criteria are applicable. Milestone 4: implement the local action plan, including a quantitative and qualitative assessment and report of the implemented actions; and Milestone 5: conduct a re-inventory to assess council progress and ensure continuous improvement in water management practices. 2. Continue reporting on water efficiency targets and performance in the council s annual report. Local governments are big users of groundwater, mainly for watering public open space, sports grounds and golf courses. Waterwise Councils will be recognised by the Government of Western Australia and provided with artwork to promote their Waterwise status within their local community. Waterwise Council Guidelines Government of Western Australia Department of Water 1

4 1 WATERWISE GARDENING INTRODUCTION THE SOIL Golden rules FAQ s SOIL IMPROVERS Organic soil improvers Soil amendments Applying soil improvers Golden rules Products available FAQ s FERTILISERS Types of fertiliser Release rates How much to use Golden rules Products available FAQ s Sources of information SOIL ph Effect on plant growth Golden rules Products available MULCH Types of mulch How waterwise mulch works Benefits of using waterwise mulch Sources of mulch Golden rules Products available FAQ s Sources of information SOIL WETTING AGENTS What makes soils become non-wettable How to overcome the problem Using soil wetters Golden rules Products available FAQ s WATERWISE GARDEN DESIGN Planning and general design principles Hydrozoning Minimising lawn Maximising comfort Shade Wind FAQ s PLANTS Exotic, Australian, Local or Indigenous? Australian plants Sources of information LAWNS Types of grass Grass alternatives Lawn alternatives Converting a grassed area to groundcovers...19 Water Corporation Waterwise Garden and Irrigation Training 2011

5 11 KEEPING A GARDEN WATERWISE WATERWISE IRRIGATION INTRODUCTION IRRIGATION EFFICIENCY IRRIGATION SYSTEMS THE WATER SOURCE SYSTEM FLOW RATE SPRINKLER UNIFORMITY PRECIPITATION RATE AUTOMATIC CONTROLLER IRRIGATION SCHEDULING RAINFALL How often to water Determine soil type and plant root zone THE AUDIT PROCESS Confirm the scope of work Preparation Conduct a sprinkler uniformity assessment CATCH CAN/CUP TEST & DATA COLLECTION Analyse data Prepare a system schedule SYSTEM MAINTENANCE IRRIGATION WATER USE EFFICIENCY MEASURES WATERING FREQUENCY Winter Sprinkler Ban Exemptions When to irrigate WATER SAVING DEVICES GREYWATER Golden rules RAINWATER Golden rules WATER EFFICIENCY SCHEMES Smart Approved WaterMark OTHER WATER EFFICIENCY ASSISTANCE Department of Water Irrigation Australia Limited Water Corporation APPENDIX ONE: WATERING ROSTERS...44

6 1 WATERWISE GARDENING INTRODUCTION Almost half of the total water used by local government is used for outdoor irrigation purposes including, open spaces, playing fields and gardens so being waterwise in this space offers the greatest opportunity to save water. It is no longer a case of briefly changing our ways to react to a short-term problem. Being waterwise is now, and ever should be, a regular part of our life. Unfortunately, some still believe that a waterwise garden will have the look and feel of a desert. Not so! Simply by adopting waterwise techniques an existing conventional garden can be maintained on far less water than previously thought possible, with little or no visible difference. Creating a new garden from scratch incorporating waterwise design, plants, irrigation, products and techniques offers even greater water saving potential. This training session is designed to refresh your waterwise knowledge and bring you up to date with the latest industry developments. It will help you to establish your council as a community leader in promoting the waterwise message and also enable you to provide quality service and impartial advice about a range of plants, techniques and products within your business and to the community. Washing machine, 7% Toilet, 9% Taps, 6% Evaporative air conditioner, 4% Leaks, 4% Dishwasher, 1% Shower & bath, 25% Irrigation, 39% Pool & spa, 2% Handwatering, 3% Average Perth residential water use. Source Perth Residential Water Use Study Water Corporation Waterwise Garden and Irrigation Training 2011 Page 3 of 44

7 Being waterwise is good for the gardener, the garden and the environment 2 THE SOIL Good soil is the foundation block of a good garden. The soil holds the key to healthy plant growth and efficient use of precious resources such as water, nutrients and your time. The top 30 cm of soil is the most critical for healthy plant growth. Soils are composed of weathered rock and are classified according to particle size. Clay has very fine particles; > mm. Clay soils have good water and nutrient holding capacity and rarely become non-wettable. Clay soils do not drain freely, are difficult to work when wet, frequently suffer from poor drainage and nutrients may not be available to plants. Loam has medium-sized particles; 0.02 mm. Loamy soils have good water and nutrient holding capacity and normally don't become non-wettable. Loamy soils are easy to cultivate and generally have good drainage. Sand has coarse particles; mm. Sandy soils have poor water and nutrient holding capacity and frequently become non-wettable. Sandy soils are easy to cultivate and have excellent drainage. Gravel has very coarse particles or aggregates; 2 20 mm. Gravel soils generally have good water and nutrient holding capacity. Gravel soils generally have moderate drainage, are often difficult to cultivate but do not usually become non-wettable. The spaces in between the particles are occupied by organic matter, air and water in varying quantities. Raising the level of soil amendments and organic matter will raise the water and nutrient holding capacity of most soil types, with the greatest increase (50 to 100 per cent) in sandy soils. Increasing the moisture and nutrient holding capacity of soil means; Less water and nutrients need be applied to deliver the same quantities to the plant and leaching of water and dissolved nutrients into the environment is reduced. There are no disadvantages. Adding organic matter also provides the right environment for a wide range of soil micro fauna which in turn assist healthy plant growth. 2.1 Golden rules Always improve the soil prior to planting all plants, especially prior to laying lawns. 2.2 FAQ s Should organic matter be added when planting natives? If the native plants are local (indigenous) species, and the soil is in a natural condition it may be possible to get away without adding organic matter. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 4 of 44

8 Healthy soil is the key to healthy plants. However, this is rarely the case. In all cases where it is intended to add extra water and nutrients, adding organic matter will be of great benefit. Even where the addition of organic matter may not be of great benefit, it certainly will not do any harm. 3 SOIL IMPROVERS The best soil improvers are those based on organic matter. Not only do they increase the water and nutrient holding capacity but they also provide the raw material that supports an active soil micro fauna. This generates a healthy soil that in turn promotes healthy plant growth. Getting the soil right is the key to healthy plants with minimum resources. Conversely, if the soil is not right, gardening can be a constant, frustrating and expensive struggle. 3.1 Organic soil improvers Compost is recycled garden and household waste that has been broken down into materials that are readily available for use in the soil. It generally has a very low level of nutrients. Making compost is part of being waterwise because compost is a valuable soil improver that helps to encourage micro fauna in the soil as well as retaining water and nutrients. Golden rules of composting Ensure the compost process does not provide a home for vermin. Do not put animal products such as meat or fat in the compost. Turn the heap regularly to infuse oxygen. Keep the moisture content similar to that of a damp sponge. Always use compost as a soil improver or in potting mixes. It is not suitable as mulch. Products available Compost bins and accessories. Animal manures have variable levels of nutrients depending upon a number of factors. Some manures may have almost no nutrients and others may have levels that are potentially damaging to both plants and the environment. All animal manures contain useful levels of organic matter. Worm farm residue is excellent material for improving the soil due to its high humus level. Bagged soil improvers and soil conditioners may be sourced from a variety of materials. Generally they have low levels of nutrients but all are good sources of organic matter. 3.2 Soil amendments Spongelite and Zeolite are naturally occurring materials that have the ability to store large amounts of water and nutrients. Though they do not directly encourage the soil micro fauna, they are very useful additives and can be used in conjunction with organic matter. Spongelites and zeolites should be mixed through the upper levels of the soil or thoroughly through a potting mix where they will persist almost indefinitely. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 5 of 44

9 Non wettable soils cause a range of problems Bentonite clay is a very fine material that can increase the water and nutrient holding capacity of sandy soils and reduces the incidence of hydrophobia. It should be mixed through the upper levels of the soil or thoroughly through a potting mix where it will persist almost indefinitely. Water storing granules are polymers which swell up as they absorb large quantities of water. When mixed through the soil they increase its water holding capacity. These granules are very useful additives for potting mixes. They should be thoroughly mixed through prior to planting. Most commercial products lose their effectiveness after 5 years. 3.3 Applying soil improvers Transplanting any plant from a pot into the garden Dig a hole about 30 cm deep and at least twice as wide as the pot, three to four times as wide will be better. Remove half the soil. Replace it with a similar amount of organic matter, add amendments and mix thoroughly with the remaining soil. If necessary, apply soil wetting agent and water in thoroughly. Make a hole for the plant, shaping the soil such that the plant will be in the bottom of a shallow saucer shape. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 6 of 44

10 Non wettable soils cause a range of problems Establishing lawn Firm the soil surface. Apply a couple of handfuls of soil amendment per square metre and then a 10 cm thick layer of organic matter over the surface. Thoroughly mix it with the soil to a depth of 20 to 25 cm. If necessary, apply soil wetting agent and water in thoroughly. If applicable, lay out subsurface drip pipe. Lay out the turf and firm down with a roller to ensure contact with the improved soil beneath. Established plants Organic matter can be applied over the soil surface but it should then be protected by covering with durable mulch. Established lawns Many established lawns received little or no soil improvement prior to being planted. There are products on the market that are can be spread over existing lawns as a top dressing. These can lead to a substantial improvement in the general health of the grass. The effectiveness of these products will be enhanced if the lawn is verti-mowed or cored prior to application. 3.4 Golden rules Improve the soil at every available opportunity. 3.5 Products available Commercial bagged soil improvers / conditioners bearing the Australian Standards mark. Products containing spongelite, zeolite and bentonite. Compost bins and accessories and worm farms. 3.6 FAQ s Can I use potting mix instead of soil improver? Yes you can but it is nowhere near as good as soil conditioner and often more expensive. Should I improve the soil for all plants? I have heard that it is not necessary with native plants. If the plant is a local one that once grew in the area, and if the soil is in its natural condition, then it may be possible to plant without any soil improvement. However, this is rarely the case. It is important to note though that many native plants are susceptible to high levels of phosphorous. As a general rule with native plants it is best to avoid animal manures or any other soil improver that contains nutrients. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 7 of 44

11 Non wettable soils cause a range of problems 4 FERTILISERS Fertiliser is the collective name for any product that contains nutrients necessary for plant growth. Fertilisers may contain differing ranges of nutrients in differing quantities and with differing rates of release. They may be organic and / or inorganic in origin. Importantly, all nutrients, whatever their source, have to be dissolved in water before they can be absorbed by plants. So watering and fertilising are closely linked to each other. It is also important to appreciate that any nutrients that are not taken up by plants enter the groundwater system and eventually find their way into our waterways. The condition of our rivers is a sad indictment of poor fertiliser practises in the past. 4.1 Types of fertiliser There is a very wide range of products on the market. Animal manures vary considerably in their nutrient content from almost nothing to occasionally quite high levels of nitrogen. All contain useful levels of organic matter and so are perhaps better regarded as soil improvers. Some animal manures that have been processed are more reliable in their nutrient levels. Blood and bone should be used with caution for it can also contain high nutrient levels. Some brands are also boosted with synthetic fertiliser. Inorganic fertilisers are formulated to suit various plants' needs. Their nutrient level is consistent. They are often damaging to soil micro fauna and contribute to altering ph levels. 4.2 Release rates The rate at which nutrients are released varies considerably. Soluble fertilisers that are added to the watering can before application release nearly all of their nutrients straight away. Plants are rarely able to take up more than a small proportion of the nutrients so there is usually considerable loss to the environment. Inorganic granular fertilisers usually have a combination of medium and fast release nutrients. Organic fertiliser may have some fast release elements but generally release their nutrients over the medium to long term. Controlled release fertilisers are designed to release their nutrients over a long period ranging from 3 to 12 months. Temperature is the major factor in determining release rates so ideally they should be incorporated into the soil for best effect. A slow release rate provides a steady supply of nutrients with a consequent reduction in wastage. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 8 of 44

12 Non wettable soils cause a range of problems 4.3 How much to use We know that in the past we have used far too much fertiliser because we have been obsessed with promoting lots of rapid and lush growth. Rapid and lush growth is not an indicator of healthy plants. In fact it is usually the opposite. The recommended rates on the packages should be therefore regarded as the absolute maximum. The best response comes from the first handful. 4.4 Golden rules Lush growth is not necessarily healthy growth. When in doubt improve the soil, don't fertilise. If a plant is sick, don't fertilise. Always use slow release fertilisers. Always water fertilisers in. Little and often is much better than large and infrequent. If possible, avoid fertilising in Winter. 4.5 Products available Fertilisers with a slow release action. Fertilisers with low nutrient levels. 4.6 FAQ s I'm not causing any damage because I only use animal manures. It's always good to use organic products but overuse of animal manures can be just as damaging as overuse of synthetic fertilisers. Not to mention sometimes being very smelly. I grow roses so I need to use special, strong fertilisers don't I? No you don't. Roses grow in the same way that all other plants do. Use a general purpose controlled release fertiliser. 4.7 Sources of information Fertilise Wise - a range of brochures for the common soil types of the metropolitan area published by the South East Regional Centre for Urban Landcare (SERCUL) The Department of Agriculture and Food also have a number of Garden/Farm Notes that deal with fertilisers. 5 SOIL ph Soil ph and the role it plays in plant growth can be very confusing. It is dealt with here because a common response to poor growth is to apply extra water and / or fertiliser when the problem may actually be due to the soil's ph level. ph is a measure of the acidity or alkalinity of the soil and can range from very acid at 4.5 to very alkaline at 9. Neutral soils have a ph of 7 which is ideal for most garden plants. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 9 of 44

13 Non wettable soils cause a range of problems The following table is a rough guide to the common soil types of the Perth Metropolitan Area: Soil Type Soil ph range Bore water Coastal 8.5 to 9.5 Usually alkaline Western Coastal Plain 6.5 to 7.0 Usually alkaline Central Coastal Plain 4.0 to 6.0 May be acidic Eastern Coastal Plain 5.0 to 6.0 May be saline Scarp 5.0 to 7.0 Not available In areas where acid sulphate soils have become exposed, the groundwater can be very acidic. If bore water is in regular use, it is very important to test the ph as well as the TDS (Total Dissolved Salts) on an annual basis. As soils become more acid the major elements of Nitrogen (N) and Phosphorus (P) and Potassium (K) become increasingly less available. Some of the trace elements also become less available. As soils become more alkaline Nitrogen (N) and Phosphorus (P) become less available as well as the trace elements of Iron (Fe), Manganese (Mn), Copper (Cu) and Zinc (Zn). 5.1 Effect on plant growth Some plants are adapted to particular soil types. For instance many of our coastal native plants will happily grow in quite alkaline soils while other plants display yellow leaves with green veins. Some common exotic plants grow much better in acid soils e.g. Gardenias, Azaleas and Camellias. While the soil can be modified by the addition of large quantities of an acid soil mix, it is much simpler to grow acid loving plants in pots using tailored potting mixes. Amending the ph of garden soil is a slow process. Applying iron in response to symptoms such as chlorosis may have some effect but it is mainly treating the symptom, not the problem. Rather than apply water or fertiliser to any ailing plant, it is preferable to conduct a soil test. Kits retail for less than $20. Electronic ph meters are also available. In all cases applying organic matter to the soil will be advantageous. It helps bring both acid and alkaline soils back towards neutral. Continuous use of inorganic fertilisers, especially the cheaper forms, will increase the acidity of soil but conversely continual use of chicken manures will increase the alkalinity. 5.2 Golden rules If in doubt, check the ph of both soil and bore water. Choose garden plants that are suited to the ph of your soil and grow other plants in pots. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 10 of 44

14 Non wettable soils cause a range of problems 5.3 Products available A ph test kit. 6 MULCH Whilst any mulch is better than none, some mulches are much better than others. Look for Waterwise mulch with the Smart Approved WaterMark, a list of these are available on their website Types of mulch There are two types of mulch. Soft mulches such as pea hay or lucerne straw are only suitable for use in high performance areas of the garden such as the vegetable patch, under fruit trees or in densely planted areas of bedding plants. The remainder of the garden should be covered with waterwise mulch. 6.2 How waterwise mulch works Waterwise mulch has large, chunky pieces that hold little if any water. The large size means large gaps between that allow water to freely flow through to the ground below while preventing water loss from the surface. The particles' irregular shape means they knit together to prevent erosion. The material should not hold water because the water should be in the soil below, not the mulch itself. Mulch with the above characteristics is very effective in reducing water loss through evaporation from the soil surface. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 11 of 44

15 Plant only low wateruse and drought tolerant lawn grasses. 6.3 Benefits of using waterwise mulch Good waterwise mulch has many benefits apart from saving water. Benefits include; Preventing erosion. Reducing weed seed germination. Reducing stress on plants' root systems. Improving the look of the garden. Feeding the soil. 6.4 Sources of mulch Mulches made from organic matter provide all the above benefits. Inorganic mulches, such as crushed brick or river stones, do not break down to feed the soil. One of the best waterwise mulches, and one of the cheapest, is tree pruning s that have been through a chipper. Ironically some one of the worst mulches, in terms of saving water is also the most popular and expensive. This is because of the addition of peat which gives the mulch a very black appearance to contrast against the colour of the plants and makes them stand out. Unfortunately the black look doesn t last very long and fades very quickly. In addition, the fine nature of these mulches mean they are easily wind blown and often knit together forming a barrier between the water being applied and the plants root system. Many mulches on the market claim to save water when they may not. Assess all mulches against the characteristics provided to ascertain whether it is waterwise. Some mulches are also claimed to be suitable for use as soil conditioner. One product cannot be both. Mulch should be coarse and raw. A soil improver should be almost totally broken down. 6.5 Golden rules Mulches should be laid to a depth of between mm. Mulch needs to be topped up regularly to maintain this minimum thickness. It is a wise precaution to keep mulch just clear of plant stems and trunks. Once in position mulch is best left undisturbed. 6.6 Products available 6.7 FAQ s Mulching machines. Mulches which match the waterwise criteria described. Look for waterwise mulch with the Smart Approved WaterMark, a list of these are available on their website at Is native plant material is suitable as a mulch? Yes it is. It may take a long time to break down but that is a good characteristic in a mulch. Should freshly chipped material be allowed to age before being spread out as a mulch? No. It can be spread out immediately without any ill effects. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 12 of 44

16 Waterwise gardens are low maintenance but never zero maintenance. But what about nitrogen draw down? Nitrogen draw down is rarely experienced when a mulch doesn't absorb water or is not constantly wet. Mulches encourage slaters and termites. Both slaters and termites need a dark moist environment. A mulch that does not hold water does not encourage them. 6.8 Sources of information 7 SOIL WETTING AGENTS 7.1 What makes soils become non-wettable Some fungi produce a waxy material during the natural process of breaking down organic matter. This wax can coat soil particles, especially the large soil particles of sandy soils as well as some gravels. This wax coating then prevents water from entering the soil, a condition known as hydrophobia or water repellence. Many Western Australian soils do not absorb water well. A soil wetting agent should be applied during the planting or laying process and again at regular intervals. A typical indication that water is not penetrating the soil is brown patches appearing in lawns. Soil wetting agents should be applied to sandy soils at the start of the Winter rains, in early Summer and again as recommended by the manufacturer. 7.2 How to overcome the problem A solution is to apply a soil wetting agent which will allow the water to soak in where it falls. Soil wetting agents are specially formulated surfactants which break down the wax barrier. They must be activated by water to be effective. In practical terms this means they should be watered in thoroughly immediately after application. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 13 of 44

17 Waterwise gardens are low maintenance but never zero maintenance. 7.3 Using soil wetters Soil wetting agents may be purchased as liquids or granules. The difference between them is only the method of application. Some soils are very water repellent and may not respond to a single treatment of wetting agent. In these cases a second and perhaps even a third application may be necessary. 7.4 Golden rules Apply wetting agents to lawns and gardens in mid Spring and again in mid Summer. In severe cases additional applications may be necessary. Always water wetting agents in thoroughly and immediately. 7.5 Products available 7.6 FAQ s Reputable soil wetting agents. Bentonite clay (for sandy soils only). Why can't I use household detergent? Household detergents contain many impurities that may be harmful. In addition they are a different formulation which is not as effective in the first instance and totally ineffective once it has dried. They are also far more expensive than soil wetting agents. Won't putting organic matter in the soil and adding organic mulches make the problem worse? In some cases adding organic matter can make the problem a little worse. However, the enormous advantages gained from adding organic matter far outweigh the disadvantages of non-wettable soil. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 14 of 44

18 Waterwise gardens are low maintenance but never zero maintenance. 8 WATERWISE GARDEN DESIGN In the past water conservation was rarely considered during the process of designing a garden. We now know that how a garden is designed can play a significant role in saving water. 8.1 Planning and general design principles When it comes to planning your design, you will need to consider: Orientation, sun and shade, the prevailing winds and water run off. Soil types, water holding capacity, compaction, water repellence and fertility levels. Availability of alternate water sources like groundwater, greywater and rainwater. Views both inwards and outwards and overall area available for the garden. Utility spaces (clothes drying, compost and storage areas), outdoor living spaces (barbeques, seating areas) and special needs (vegetable garden, swimming pool etc). Plant preference and design styles (native/exotic, formal/informal etc). Maintenance expectations and available budget. Maximising the use of non-planting treatments such as paving and mulches. At the same time, be aware of excessive unshaded paving which can be hot and glaring. Keeping planted areas dense and consolidated. Sparse scattered plants are more difficult to water efficiently than ones that are in defined areas. Keeping lawn for functional and aesthetic requirements. Lawn should never be used as a 'filler'. Choosing a lawn type that is water efficient and best suited to your soil. See section 10 for more on water efficient lawns If you are establishing a new lawn or garden you may apply for an exemption for it to become fully established if you meet the criteria. Obtaining expert advice on irrigation from our list of Waterwise Specialists or call the Waterwise Helpline on Hydrozoning Hydrozoning is grouping plants with similar water needs together in an effort to be more water efficient. This is one of the most important tools to conserve water in the garden, and helps save money too. Apply the following principles of hydrozoning to plant selection and arrangement: A broad selection of plants may be used, but keep high water-demand plants to a minimum. Arrange plants having similar water requirements together and take this into account when deciding soil improvement and mulching, and when managing irrigation. Garden plants can be split into three groups according to their water needs. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 15 of 44

19 Waterwise gardens are low maintenance but never zero maintenance. Hydrozone one - plants are those with a low water requirement. They will only need occasional watering over Summer. No more than once a week and many perhaps once every two weeks or longer. Hydrozone two - plants have a moderate water requirement. These plants will need to be watered every 3 to 7 days during Summer. Hydrozone three - plants have a high water requirement. These plants will need to be watered every 1 to 2 days during Summer. The above ratings assume that the plants are well established in an improved soil. All will need less frequent watering at cooler and wetter times of the year. Waterwise Garden Centres label their plants to signify the appropriate hydrozone. The Water Corporation s Waterwise Plants for Perth is a searchable database that has hundreds of species of one drop plants. 8.3 Minimising lawn There is no substitute for grass for a playing area. However the role of a lawn should be carefully considered. Many private gardens have large areas of lawn that are never used or simply grown as fillers e.g. verges on many large corner blocks. While some grasses can be fairly water efficient, most gardeners overwater their lawns. So the more lawn they have, the more likely they are to overwater. In a waterwise design only a warm season waterwise turf like kikuyu or soft leaf buffalo should be used and if lawn is unnecessary then avoid planting it. 8.4 Maximising comfort Many gardens have areas that need no watering, especially paving. In a waterwise design non watered areas should be maximised but not to the point where comfort is sacrificed. Large areas of unshaded paving create a hot box which also affects the temperature inside the house. 8.5 Shade In our climate the value of shade in the garden is often overlooked. Many plants grow well in light or partial shade provided by trees, large shrubs and pergolas. Shade drastically reduces temperatures and increases the comfort of both people and plants. 8.6 Wind WA is one of the windiest regions in the world. Rapid air movement causes plants to transpire greater amounts of water. Hot dry winds can cause serious damage to delicate plants. Protecting plants from the wind reduces both water use and stress. The best protection is provided by a windbreak that filters the wind, allowing some through but slowing it down. Tough native shrubs make the best living windbreaks. By controlling or at least moderating the effects of wind and sun it is possible to create microclimates within a garden where some of the more delicate plants can be grown. For expert advice and professional waterwise garden design contact a Waterwise Garden Landscaper. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 16 of 44

20 Waterwise gardens are low maintenance but never zero maintenance. 8.7 FAQ s What can I use instead of grass? There are many alternatives including prostrate ground covers that may be walked on and a wide range of higher growing ground covers with colourful flowering habits. In addition to looking good these plants generally have a lower water requirement than grass. How do I have shade in Summer but sun in Winter? It is possible to design verandahs and pergolas to block out Summer sun but allow Winter sun in. Deciduous trees and vines can also be used to great effect. Where I need to have a windbreak is where my best view is. Unfortunately that is often the case. An open shrub which filters some wind but doesn't totally block the view is the best compromise. 9 PLANTS We have a climate in which it is possible to grow a very large range of plants. These plants come from all over the world from a range of climates and soil types. Those from soils and climates similar to ours are very easy to grow. In fact many grow so well that they have become weeds. At the other extreme are plants from heavier soils and wetter climates that often need constant attention and greater amounts of water and fertiliser. 9.1 Exotic, Australian, Local or Indigenous? Australian plants There is no doubt that the plants most likely to flourish in our climate and soils are those that have developed here over a long time. They are also the plants that support the local fauna that is a very important part of a healthy garden. For the purposes of the notes that follow a native plant is defined as one of Australian origin which comes from reasonably similar soils and climate to those where it is to be planted. Plants that naturally occur in the same soil type in the local area are referred to as local plants and those that occur in the immediate area are referred to as indigenous plants. The range of native plants available to consumers has increased dramatically in recent years with the introduction of many more species. Perhaps more significantly, the range of cultivars has also increased, as plant breeders select smaller forms with longer, more colourful flowering periods that are better suited to ornamental horticulture in the suburbs. The range of local plants is also increasing as local growers cater for an increasing demand. Indigenous plants can sometimes be difficult to source but constant demand generally leads to supply. Local Plant groups and the Wildflower Society often offer plants of known provenance. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 17 of 44

21 Waterwise gardens are low maintenance but never zero maintenance. 9.2 Sources of information Waterwise Plants for Perth is a searchable database that contains close to a thousand freely available plants, that once established will thrive on one watering a week or less. The website contains detailed notes and photographs on each plant. To use the database go to the Water Corporation website at and follow the Being Waterwise links. There is also an excellent range of Grow Local Plant guides published by the South East Regional Centre for Urban Landcare which details local plants suitable for each of the five major soil types in the metropolitan area. These are available on the website and free of charge from many local authorities and community groups. Many local authorities produce their own plant lists. 10 LAWNS Lawns should only be planted where they are needed and never as a filler. Where lawn is needed it is important to use a grass that has a low water demand and high drought tolerance. These are called warm season grasses and include kikuyu, buffalo and cultivars of soft buffalo and couch. All benefit greatly from soil improvement with organic matter and amendments prior to planting Types of grass Each particular variety has its own characteristics and special care requirements. Warm season grasses are mostly grown from rolls or runners. Cool season grasses are mostly grown from seed and are not recommended as lawns though they may be convenient for short term repair jobs. Most established lawns benefit greatly from a top dressing with a material that is rich in organic matter Grass alternatives Lippia (Phyla nodiflora) is the hardiest lawn substitute. Once established, it needs very little water. There is concern about its potential to become a weed in WA. Lippia can be mown and will tolerate full sun and heavy foot traffic as well as very alkaline soils. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 18 of 44

22 Waterwise gardens are low maintenance but never zero maintenance. Dichondra, also known as Kidney weed, requires about the same amount of water as a warm season grass. Its advantage lies in its ability to grow in heavily shaded areas. It often self seeds. Native violet (Viola hederaceae) is a native violet that spreads by runners to cover large areas. It is a native of the South East of Australia and needs a lot of water in Summer. It is generally only suitable for highly shaded and protected areas Lawn alternatives There are literally hundreds of low growing, hardy ground covers that can be used instead of grass. Prostrate green leafy plants can be used to give the appearance of a lawn or seasonally colourful flowering groundcovers can be planted to create an ever-changing patchwork of colour Converting a grassed area to groundcovers This is quite a simple task involving the following steps; 1. Water and fertilise the lawn to promote growth. 2. When it is growing well apply a glyphosate based herbicide at the recommended rate, making sure that every single part of the lawn is treated. 3. Find and remove any in ground sprinklers and disconnect the supply pipe. If the sprinklers are linked to a controller that station should be disconnected too. 4. Wait 3 to 6 weeks for the grass to die. It will take longer in Winter than Summer. 5. While waiting for the grass to die, choose and purchase new plants for the area. 6. Cut holes in the dead turf, improve the soil and plant. 7. Connect an integrated dripper system to the old supply line, weave it around the new plants, peg it down every metre or so with bent wire hoops and then cover with mulch. 8. If the integrated dripper pipe is linked to a controller (see step 3), reconnect it and alter the programme. If you selected plants using the Waterwise Plants for Perth website allow that station to operate for about 20 minutes twice a week for a few weeks then down to once a week. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 19 of 44

23 The finer the spray the greater the evaporative loss. 11 KEEPING A GARDEN WATERWISE Most gardens need regular maintenance to ensure they remain waterwise. Waterwise gardens are usually low maintenance but are never zero maintenance. Maintenance includes: Topping mulch up regularly to keep a minimum thickness of mm. Applying soil wetting agents to both lawns and gardens on sandy soils on a regular seasonal basis. Not promoting unnecessary growth, especially lush growth by using a lot of fertiliser. Lush growth is more susceptible to attack by pests and diseases. High fertiliser use also means high water use. In most gardens plants are given far more nutrients than they can use or need. Use slow release fertilisers for greatest efficiency and least pollution. Controlling weeds which compete with desirable plants for available moisture. A mulched surface makes weed removal easier. Pruning excess growth from plants after they have flowered and or fruited to reduce their water needs. Checking the irrigation while it is working on a regular basis and correcting any problems. Adjusting the controller programme to ensure that watering frequency is correct for the season. A lot of water is wasted because gardens are watered twice a week at cooler times of year when the system should be turned off or when once a week is more than sufficient. 12 WATERWISE IRRIGATION INTRODUCTION The irrigation market covers agriculture, horticulture and landscape. The landscape segment can be divided into: Residential/Light Commercial Home gardens Office and industrial properties Areas less than 2000m Commercial Public open space Streetscapes Sports fields Golf courses. In Perth, and in WA, water used for irrigation is managed in three distinct ways: Residential/Light Commercial Using potable water regulated by water restrictions, one or two days per week and a total winter ban; or using groundwater (bore or well) for an irrigated area less than 2,000m², regulated by water restrictions, three days per week and a total winter ban. Commercial Using groundwater (bore or well) regulated by a Groundwater Licensing process, which is administered by the Department of Water. This is also subject to a winter ban, with exemptions given for some types of use. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 20 of 44

24 Integrated dripper tubing is very efficient. Agricultural/horticultural Agricultural/horticultural use is also regulated by the licensing system. However, groundwater allocations are related to, and vary depending on the production of the enterprise (i.e. the area and type of crop) The audit process will evaluate the water use efficiency of an existing irrigation system in its normal working condition; including the distribution uniformity of the sprinkler layout. This process also gathers data on the irrigation system which enables the auditor to prepare a basic watering schedule, which can be developed into an annual water budget for the system. Where historical water consumption records are available, the audit process should determine the potential for water savings, compared to previous water use. The objectives of an irrigation system audit can be summarised as follows: To determine how efficiently irrigation water is being applied. To determine how water can be saved by improved application and scheduling efficiency, and To prepare a basic irrigation system schedule. Common terminology used in the Irrigation Industry: One Hectare Ha square metres 2.45 acres One Kilolitre or kl 1000 Litres One Cubic Metre m Litres One Imperial Gallon 4.55 Litres One USA Gallon 3.8 Litres One Megalitre ML 1000 Kilolitres One Gigalitre GL 1000 Megalitres 1mm depth over one square metre One Litre One metre of pressure head 9.8 kpa 1.42 psi One Bar 100 kpa One PSI 6.89 kpa 0.7 metres head One Horsepower HP 0.74 KW One Kilowatt of Power kw 1.34 HP 13 IRRIGATION EFFICIENCY An efficient irrigation system should distribute enough water to sustain plant life and use an efficient watering schedule that conserves water. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 21 of 44

25 Integrated dripper tubing is very efficient. Distribution efficiency refers to how effectively water is delivered from the water supply source to the plant root zone and should consider the following: Good design and product selection The water source Efficient pumps Correct system pressure Sprinkler uniformity Good maintenance. Scheduling efficiency refers to how much water and how often. If this is not interpreted correctly it could lead to inefficient water use in landscape irrigation systems. A correctly scheduled system should achieve some or all of the following: No run off Apply enough water to only water the plant root zone No deep percolation beyond the root zone Regular adjustments to the system program Turn the system off after a rainfall event. The irrigation schedule balances the changing requirements of the landscape with the capabilities of the irrigation system. An assessor must understand the system, the factors likely to affect its performance and the water demand. These factors are: Type of plant being irrigated Type of use of the area (i.e. active or passive) Type of irrigation system Precipitation rate of the sprinkles/emitters being used Sprinkler nozzle pressure, and Sprinkler spacing. It is unlikely that there will be a single schedule for a particular landscape and it should change depending on the weather, the plants being watered and the time of year. The schedule should consider the constraints imposed by the irrigation system hardware, and any restrictions required by regulating authorities. Efficient watering Water Corporation Waterwise Garden and Irrigation Training 2011 Page 22 of 44

26 Keep an eye on how much water is being applied. 14 IRRIGATION SYSTEMS The majority of landscape irrigation systems use automatically controlled pop up sprinklers. Large turf and garden areas use rotor type sprinklers while smaller areas have fixed spray heads, small rotators or to a reduced extent, drip irrigation systems. Trees can be irrigated with individual bubblers installed at the base of each tree. An irrigation auditor must be able to recognise the different system types and understand the different operating parameters of each system. Following are the basic types of systems. Fixed spray head sprinklers have no rotating parts. The water is directed through holes in the sprinkler head in a fixed spray pattern over the irrigation area. Spray heads have a radius of throw between 0.75 and 5.5 m and precipitation rates from 15 to 65 mm/hr. They are typically used for small and irregular turf areas, shrubs, trees and flower-beds. Stream rotor sprinklers have a rotating gear arrangement, which moves multiple streams of water, designed to cover different radii, through a predetermined arc. Stream rotors have a typical radius of throw from 6.0 to 14.0 m and precipitation rates from about 12 to 20 mm/hr. They are commonly used for mid-size turf applications, large flower-beds, and ground cover. Stream rotor sprinklers in operation Geared rotor sprinklers move water through a combination of one or more carefully shaped nozzles, and rotates the nozzle head in a predetermined arc. Geared rotors have a large radius of throw, ranging from 6 to 30 m, and precipitation rates from 2.5 to 25 mm/hr. They are typically used for large turf areas and ground cover applications. Geared rotor sprinklers in operation Water Corporation Waterwise Garden and Irrigation Training 2011 Page 23 of 44

27 Make sure you know your watering roster. Impact sprinklers usually have one or two nozzles, which are rotated by a reciprocating spoon that pivots the nozzles around in a circular pattern. Impacts have a large radius of throw, ranging from 9.1 to 40 m, depending on the actual sprinkler selected, and precipitation rates from 2.5 to 20 mm/hr. These sprinklers are typically used for large turf areas and these days are more commonly found in older landscape systems using aluminium spray lines, hose end sprinklers or in agricultural applications. Drip emitters have flow rates ranging from 1.0 to 24.0 litres per hour (lph), and are typically installed along a polyethylene pipe at intervals equal to the plant spacing. The number of emitters per plant is based on the size and type of the plant and the hours available for irrigation. In-line drip systems use polyethylene pipes with drippers extruded into the pipe. Water is discharged by the systems at similar rates to drip emitters and discharge rates also vary according to the spacing of the drippers, which can range between 250 mm centres to 500 mm centres. In-line drip irrigation Micro sprays are low-flow spray emitters with flow rates ranging from 30 to 100 lph, and are typically installed along a polyethylene hose using 4 mm tube and a support stake. As with drip emitters, the number of micro sprays per point is based upon the type and size of the plant material and the hours available for irrigation. 15 THE WATER SOURCE Water for irrigation systems may be sourced from any one or more of the following: Groundwater from a bore or a well Water Corporation scheme supply (i.e. mains water) Treated wastewater Surface storage Stormwater, and River or creek. The majority (but certainly not all) of commercial landscape irrigation systems in the Perth metropolitan area use groundwater taken from the shallow aquifer using a groundwater bore equipped with an electric submersible pump. Pump flow rates vary widely but are usually within a range of 3 to 20 litres per second. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 24 of 44

28 Make sure you adjust your irrigation controller according to the season. Groundwater bore pump discharge pipework All commercial bores and use of groundwater require licences to a) sink the bore and b) extract water. This process is administered by the Department of Water. The licence to extract water specifies the annual allocation (kl/year) as the maximum amount permitted for the particular site. The licence will also nominate a number of conditions the operator must adhere to. The assessor must identify the water source and should be given access to a copy of the groundwater licence, which will state the area of irrigation in hectares, and the annual allocation in kilolitres, which can be extracted. This allocation needs to be managed carefully as it can play a significant part in the annual water use budget. 16 SYSTEM FLOW RATE The system flow rate is important as it provides statistical base data for monitoring water use. A flow meter should be installed to record the flow rate in L/sec or cubic metres/hour and should have the ability to show the cumulative volume used (in cubic metres). The most accurate way to calculate the flow rate of a sprinkler zone, while it is operating, is to observe the water meter, if one has been fitted. Auditors can easily check the flow rates if the irrigation system is operated from a dedicated bore and pump that also has a meter. If the system operates off scheme water, meters will monitor the combined flow to buildings as well as the irrigation system. In some situations, an auditor may need to use data from other sources to estimate system flow rates, such as hour run meters on pumps plus the pump performance data. As an alternative to reading the water meter, auditors could determine the size of the sprinkler nozzle and obtain the flow rate and operating pressure from the manufacturer. This will enable the auditor to estimate the flow rate Water Corporation Waterwise Garden and Irrigation Training 2011 Page 25 of 44

29 Make sure you adjust your irrigation controller according to the season. 17 SPRINKLER UNIFORMITY It is virtually impossible to obtain 100% sprinkler uniformity which is affected by: Sprinkler spacing Nozzle pressure Wind effect Landscape features including trees, shrubs, garden beds, etc. To overcome this, sprinkler systems must be designed so individual sprinkler patterns overlap to provide a reasonable level of uniformity. The maximum distance between turf irrigation sprinklers should be no greater than 50% of the diameter of throw of the selected sprinkler. Inconsistent spacing will adversely affect uniformity. Good uniformity means nearly equal amounts of water being deposited on each square metre (m²) or irrigated area especially on turf, which has similar root zone characteristics. As root zones under trees and shrubs vary, uniformity lower than the square meter level is acceptable as long as vegetation receives adequate water. Selecting the right sprinklers during the system design process and having a robust installation and maintenance program will ensure good performance during the life of the irrigation system. Sprinkler uniformity is measured in three ways: distribution uniformity (DU), coefficient of uniformity (CU) and scheduling coefficient (SC). This process can also be used for drip systems. Distribution uniformity is the most common method used for landscape irrigation systems and can be determined by conducting a catch can/cup test on the part of the system under scrutiny. DU of 75% or greater is acceptable within the irrigation industry. Data collected can be used to calculate average precipitation rates of sprinklers. The following diagrams show a typical sprinkler profile and demonstrate how sprinkler overlap can achieve the best uniformity of distribution. Typical sprinkler profile Water Corporation Waterwise Garden and Irrigation Training 2011 Page 26 of 44

30 Make sure you adjust your irrigation controller according to the season. Sprinkler overlap 18 PRECIPITATION RATE Precipitation rate simply means the rate at which a sprinkler system delivers deliver water to the ground and can be calculated as mm/hour and averaged within a watering zone. Knowing the precipitation rate/s of an irrigation system is essential for an auditor to determine how long sprinklers need to run to apply the required amount of water. For Example: If the precipitation rate of a group of sprinklers is 40 mm/hour (see spray heads in Figure 8.4 above) and 10 mm of water is required, the run time will be: 10/40 x 60 = 15 minutes If the precipitation rate of a group of sprinklers is 11 mm/hour (Figure 8.2 above) and 10 mm of water is required, the run time will be: 10/11 x 60 = 55 minutes It is important to understand that not all sprinklers deliver water at the same rate. Uniformity Evaluation Table Water Corporation Waterwise Garden and Irrigation Training 2011 Page 27 of 44

31 Make sure you adjust your controller according to the season. Sprinkler precipitation Sprinkler precipitation rates must be determined to ensure watering rates are not greater than the ability of the soil to absorb water, which can lead to run off and reduced efficiency. Depending on the pressure, spacing, and type of sprinkler selected by the designer, each individual station on an irrigation controller may have different precipitation rates. At many sites, it is possible to use a water meter to measure the steady-state flow of irrigation stations. If the flow rate into a station and the total irrigation area is known, it is possible to estimate the average gross precipitation rate which is known as the total area method. 19 AUTOMATIC CONTROLLER An irrigation system has a controller and an auditor should identify the make, model and features so it can be programmed to suit the watering requirements including multiple start times. Before making any changes the auditor should take note of the current controller settings at the time of the audit. Changes can only be made when the system parameters are known, including: The precipitation rates of the sprinklers or emitters on each station, The amount of water required by the plants on each station, The days on which the system will turn on, The time at which the system will start, Water Corporation Waterwise Garden and Irrigation Training 2011 Page 28 of 44

32 Scheduling means applying the right amount of water to plants at the right time. The run times for each of the remote control (solenoid) valves which are connected, to the controller, and, Any water restrictions that must be adhered to. Each controller station should only run long enough to provide adequate moisture to the root zone of the plant type being irrigated. During the year, settings should be adjusted at least monthly to suit the changing climatic conditions and plant water requirements. During winter months, 1 June to 30 August, automatic reticulation system controllers in the Perth metropolitan area and the majority of the state s south west region should be turned to the Off position, because winter sprinkler bans apply. 20 IRRIGATION SCHEDULING Scheduling means providing plants with the right amount of water at the correct intervals. To do this effectively, an auditor must have at least a basic understanding of the plant/soil relationship and water needs, plus the rate of evaporation and moisture loss through plant transpiration (moisture lost through leaves). Weather conditions and the amount of water used within a landscape vary from day to day and this should be considered when estimating the scheduled watering requirements. Effective irrigation schedules are determined by key factors including climate conditions, plant types, soil types and plant root depth. Evapotranspiration includes evaporation and transpiration Water Corporation Waterwise Garden and Irrigation Training 2011 Page 29 of 44

33 Rainfall influences the amount of irrigation water required. Sunlight as solar radiation plays a role in moisture evaporation and plant transpiration and is affected by the intensity of the sun, cloud cover, altitude and shading from nearby plants, structures or terrain. Wind is also a factor and depending of its velocity across leaf and soil surfaces moisture is lost at varying rates. Wind direction and duration influences the moisture loss as well as obstacles such as trees, shrubs and nearby buildings and fences. Air temperature influences the rate of transpiration from plants and evaporation from soil; higher temperatures result in a more rapid loss of water from the landscape. Humidity is a measure of the water vapour content in the air. Lower humidity (dry air) provides a greater differential between the moist leaf surface and the air and this increases the rate of water loss from the plant. Humidity is typically quantified as relative humidity (relative to completely saturated air). Evapotranspiration (ET) is influenced by other factors including plant species, stage of growth of the plant, density of planting, the micro-climate of the area being irrigated and the amount and quality of water available to the plant. ET is expressed in terms of a depth of water per unit of time such as millimetres per day, week, month, or year. ET is a useful reference point for calculating irrigation water use because it represents a specific rate of use in response to the local weather conditions. There are several ways to obtain estimates of evaporation/transpiration. They are: Local sources (such as the Bureau of Meteorology) Measuring the depth of water evaporated from an open pan (pan evaporation) Computer services Lysimeter Historical Although ET is only an estimate it is accurate enough for planning and budgeting water, but the irrigation system must be fine-tuned to meet the needs of the area being irrigated. 21 RAINFALL Rainfall influences the amount of irrigation water required and this needs to be considered in two different ways. Because we are unable to accurately forecast the timing or extent of a rainfall event, the auditor cannot plan for this in the irrigation schedule. The scheduling requirements, and the controller settings should be programmed on the basis of zero rainfall. In the event of a rainfall event, the system should be turned off for an appropriate period of time. For example, if there was a rainfall event where 10mm of rain fell, and we know the daily plant requirement is 5mm/day, then we could turn the system off for two days. The second way that rainfall influences the amount of irrigation water required is in the total annual irrigation water requirement. (e.g. kl/year) If it did not rain at all during a year, then 100% if the plant requirements would need to be provided by irrigation. However historical data can provide us with an average annual rainfall for most areas, which provides us with base data for planning. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 30 of 44

34 The frequency of irrigation depends on the soils water holding capacity. One of the difficulties is deciding what proportion of the total average annual rainfall actually ends up in the root zone. This proportion is referred to as the effective rainfall. Some rainwater does not reach soil because it is held in mulch, or thatch or it runs off. Some water may percolate below the rootzone and be lost, depending on the intensity and duration of the rainfall event, and the water content of the soil prior to the rain. Therefore the irrigation manager must make an estimate of the effective rainfall which will impact on his system. The following figure provides a sample of how climate data can be used to compile a guide for plant water requirements. Weekly scheduling guide for an irrigation system Fact or Unit Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Total Av monthly mm evaporation Av monthly rainfall mm Assumed effective 0% mm monthly rainfall Av net monthly mm requirement Weekly requirement mm Adjusted fro crop factor. This is the net irrigation requirement 0.50 mm/ wk Adjust for application efficiency. This is the gross irrigation requirement 0.85 mm/ wk Irrigation water requirement 21.1 How often to water The frequency of irrigating in an effective watering schedule will depend on two things, the ability of the soil to hold the water and how deep plant roots grow. Soil texture describes the size of individual soil particles such as sand, silt, or clay. Soil texture is divided into a class to describe the relative amounts of sand, silt, or clay in that particular soil. The class name may be sandy loam, loamy clay, silty clay loam, etc. Soil texture has a major influence on: The amount of water that can be stored in a soil Soil infiltration rates (the rate water can be absorbed into a soil), and Permeability of a soil (the rate that water can move through a soil). Soil structure describes how mineral particles and organic matter are arranged to form aggregates. Soils with good structure hold more water, which is available for plant use, than those with poor structure. Soil particles form part of the soil makeup including primary elements (sand, silt, or clay) or secondary aggregated particles. Examples of soil structure include clods and granules. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 31 of 44

35 An audit can help you identify if your irrigation systems are operating efficiently. When a saturated soil has been allowed to naturally drain for a specified time (usually one to two days depending on soil structure), the soil is said to be at field capacity. Additional drainage is almost nonexistent. The amount of water contained in the soil is determined by laboratory procedures and is usually expressed in units per unit of soil depth (millimetres per metre). When plants can no longer extract moisture from the soil the permanent wilting point (PWP) has been reached. The PWP of a soil can be determined in the laboratory by subjecting a soil sample minus 15 atmospheres of tension, which is the approximate tension at which plants irreversibly wilt due to moisture stress. The total water holding capacity of a soil is the amount of moisture it can store between field capacity and the PWP. The available water holding capacity (AWHC) is always less than the total water holding capacity, which refers to the total amount of water that is available to the plant. Soil texture class Soil awhc (mm/m) Final basic intake rate (mm/hr) Clay Loam Sandy loam Loamy sand Sand Indicative soil water holding capacities and infiltration rate by soil texture. Infiltration rate is a measure of how quickly water enters a soil; the longer water is applied the slower this rate becomes. Infiltration rates play an important role in managing landscape soils because they influence how rapidly water can be applied without run off. Compacted soils, thick thatch, and slopes all reduce infiltration rates. For irrigation scheduling purposes, it is useful to physically observe and record the elapsed time at which run off begins to occur. With pressurised irrigation systems the rate water is being applied should not exceed the soil s infiltration rate. Exceeding the infiltration rate can, depending on the situation, result in soil damage, cause erosion, loss of fertilisers, and excessive water logging of the root zone in low-lying areas. Percolation rate is the rate at which water drains through the soil. Deep percolation occurs when water drains below the root zone and is lost and fertilisers and other chemicals can leach from the root zone down into ground water. Most of the water losses in landscape irrigation occur through deep percolation, which cannot be seen and is not easily measured. Many landscape managers attempt to overcome poor uniformity by applying more water than is necessary, so an adequate amount is received at the driest location. This practice is one of the leading causes of deep percolation. Good distribution uniformity minimises the amount of extra water needed to provide an adequate supply to the driest location in the system. Run off is water that is not absorbed by the soil or landscape, instead the water ponds, evaporates or flows from the area. Run off may result from water being applied at a rate greater than the soil infiltration rate. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 32 of 44

36 An audit can help you identify if your irrigation systems are operating efficiently. Active root zone is the soil depth from which a plant extracts most of its water needs. The active root zone is expressed in millimetres or metres. A deeper plant root system means the plant can access more of the available soil moisture, which will reduce the frequency of irrigation events Determine soil type and plant root zone Taking a soil core sample Root zone available water (RAW) represents the quantity of water stored within the root zone between the conditions of field capacity (after drainage) and the PWP (when the plant can no longer extract significant amounts of water and dies). 22 THE AUDIT PROCESS 22.1 Confirm the scope of work As auditing and assessing a system mean different things to different people, always define the requirements and expectations of the person who requests an assessment to be conducted Preparation Preparing for the assessment process is critical to ensure all available data is collected, tested and evaluated efficiently. An initial site visit should be made and a quick run through of the system (i.e. operate each station and observe the sprinklers operating) carried out to ensure all stations work, and all sprinklers operate and there is no evidence of major leaks or other problems. Generally, it is not the auditor s role to fix any such problems, but they should be rectified prior to conducting the audit. The initial site visit is also an opportunity to gather basic data such as controller settings, water source and water use records, if available, as well as the total area and plant types being irrigated. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 33 of 44

37 Make every drop count. The specific section on which to set up the field test can also be determined during the preliminary visit. The auditor should also review a copy of the as constructed drawing of the irrigation system Conduct a sprinkler uniformity assessment Using information gathered during the initial site visit, prepare an audit plan and identify a specific area or areas for the catch can/cup test. Systematically distribute the catch cans/cups throughout the sprinkler stations and run each station briefly to measure the water collected in each container. The system performance (precipitation rate and distribution uniformity) can be determined from the data collected A residential catch can layout Water Corporation Waterwise Garden and Irrigation Training 2011 Page 34 of 44

38 Make every drop count. The following table provides a summary of the process used in a sprinkler catch devise test. Step One: Run the system (turn pump on) Flag the sprinklers in the area to be tested Turn pump off Step Three: Turn pump on Run the systems (10 or 15 minutes) Record: o Pump pressure o o Pump amps Water meter reading (flow rate, L/sec) Count the number of sprinklers operating on each station Check the sprinkler rotation speed and arc of operation of each sprinkler Record sprinkler nozzle pressures as follows: o At a sprinkler in the test area o At the first sprinkler on the line o At the last sprinkler on the lin Take soil core sample Record controller details and settings Turn off the pump and record the test run time. Field evaluation process Step Two: Measure and record the sprinkler spacings (m) Check and record sprinkler nozzle sizes Setup 24 catch cans/cups use 6 rows of 4 Read and record the meter reading (total kl) Step Four: Reconrd all catch can/cup reading Read and record the meter reading (total kl) Retrieve all test equipment Return to base to process the data collected 23 CATCH CAN/CUP TEST & DATA COLLECTION a) b) c) d) e) f) Water Corporation Waterwise Garden and Irrigation Training 2011 Page 35 of 44

39 Audit your irrigation system and prepare a schedule to make sure you are irrigating efficiently. a) Operate the system and flag heads b) Test nozzle pressure and record data c) Measure sprinkler placings and record the data d) Check soil type and plant root depth e) Layout of the catch cans and operate the system for a specific time e.g. 15 minutes f) Read the catch can and record the data 23.1 Analyse data The auditor will analyse all available data including information collected during the initial visit and during the system testing. From this data, the auditor will provide estimated plant water requirements based on plant types and soil types, determine the uniformity of the sprinkler layout, and prepare a schedule to operate the system. Where historical water use records are available, a comparison of how much water has been used and how much should be used, can be provided. Depending on the skills and experience of the auditor, he/she may also provide recommendations on how water use efficiency can be improved Prepare a system schedule Having conducted the audit and determined all of the scheduling parameters, the system schedule can be prepared. There is no standard way to prepare or present a schedule, as this is usually designed to meet the needs of a specific site and operator. Schedules can be simple or more detailed depending on the needs of the user. Following are some examples of system schedules. GROSS IRRIGATION REQUIREMENT Daily requirement based on 5 day cycle Sprinkler Precipitation Rate (mm/hr) Station Run Times for Daily Requirement (mins) Fact or Mm /da y 11 Mm /hr Unit JAN FEB MAR AP R MAY JU N JUL AUG SEP OCT NOV DEC Mm /wk off off off Water Corporation Waterwise Garden and Irrigation Training 2011 Page 36 of 44

40 Audit your irrigation system and prepare a schedule to make sure you are irrigating efficiently. Example of water use when programming on basis of minutes. Average flow 25kL/hr (6.9L/sec) x 40.4 hrs/week = 1010kL/week used. Example of water use when programming on basis of mm. Average flow 25kL/hr (6.9L/sec) x hrs/week = 894kL Water Corporation Waterwise Garden and Irrigation Training 2011 Page 37 of 44

41 Regular maintenance is necessary to ensure the irrigation system is operating efficiently. 24 SYSTEM MAINTENANCE Regular maintenance is necessary to ensure the system operates at its optimum efficiency. A poorly maintained system will waste water. Following are some of the common maintenance activities that can be implemented to minimise water wastage: Repair faulty solenoid control valves, Replace missing or damaged sprinkler nozzles and always replace like with like to maintain the,integrity of the original design, Repair faulty or damaged sprinklers, maintain correct sprinkler heights and vertical settings, Maintain adequate system pressure for correct sprinkler operation, Repair any leaking pipes or fittings, Adjust controller run times, at least monthly, Keep sprinkler arcs adjusted corre,ctly, Clean filters on drip systems Check for leaks in damaged drip pipes or drippers, Periodically test automatic switches and sensors to ensure satisfactory operation, Trim shrubs and plants that interfere with the sprinkler stream, Mulch garden beds, and Apply wetting agent. a) b) a) Example of low sprinkler pressure (i.e. 200kPa at nozzle instead of 400kPa) b) Example of incorrect sprinkler height 25 IRRIGATION WATER USE EFFICIENCY MEASURES There is a cost involved to achieve water use efficiency. This cost comes from using more complex components, or a design that allows for more specific and accurate applications of irrigation water, e.g. use of part circle sprinklers. This cost is more easily justified when using scheme water for irrigation, (i.e. high cost per kl) than is the case when using groundwater, where the cost amounts to the running and ownership of the pumping equipment. However, there is a social and environmental obligation to minimise water use, and greater regulation of groundwater means users of this resource are expected to use groundwater carefully and efficiently. Water Corporation Waterwise Garden and Irrigation Training 2011 Page 38 of 44