IRRIGATION. Operate irrigation systems. RTE3611A Operate pressurised irrigation systems. RTE3610A Operate gravity fed irrigation systems

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1 IRRIGATION L E A R N I N G G U I D E Operate irrigation systems Supports learning against competency standards RTE3611A Operate pressurised irrigation systems RTE3610A Operate gravity fed irrigation systems Developed by the Irrrigation Association of Australia with funding from NSW Department of Education and Training

2 L E A R N E R S G U I D E Operate irrigation systems Supports learning against competency standards RTE3611A Operate pressurised irrigation systems RTE3610A Operate gravity fed irrigation systems Name Address Phone Fax

3 NSW Department of Education and Training (DET) 2002 All rights reserved. This work is copyright, but permission is given to trainers and teachers to make copies by photocopying or other duplicating processes for use within their own training organisations or in a workplace where training is being conducted. This permission does not extend to the making of copies for use outside the immediate training environment for which they are made, nor the making of copies for hire or resale to third parties. Outside these guidelines, all material is subject to copyright under the Copyright Act 1968 (Commonwealth) and permission must be obtained in writing from the NSW Department of Education and Training. Disclaimer The views expressed in this work do not necessarily represent the views of the NSW Department of Education and Training. The NSW Department of Education and Training does not give warranty nor accept any liability in relation to the content of this work. Project Team Puncheon Pty Ltd PO Box 18 NORTHMEAD NSW 2152 Project Steering Committee Irrigation Association of Australia Tim Hodgkins (chair) and Alison Carmichael Australian Horticultural Training Greg McPhee NSW Primary Industry Training Advisory Board Susan Crowley NSW Department of Education and Training Claire Cappe NSW Agriculture Steve Elliot and Lyn Batten Rural Training Council of Australia Tony Audley Further copies of this resource are available from... Irrigation Association of Australia PO Box 1804 Hornsby Westfield, NSW 1635 Tel: (02) Fax: (02) [email protected] Website: Acknowledgement This work has been produced initially with the assistance of funding provided by the NSW Department of Education and Training, Training Development Unit, through the Industry Skills Training Program advice from the Project Steering Committee. 3

4 Contents Introduction...5 How to use this Learning Guide...6 Getting started...8 TOPIC 1 Soil/Plant/water relationships...10 Plant/soil/water relationships...10 Plant water requirements...10 Factors affecting plant water use...11 Soil water principles...13 Topic 1 Activity Soil water movement...16 Topic 1 Activity TOPIC 2 Calculating water requirements...20 Calculating available water...20 Topic 2 Activity Topic 2 Activity Calculating available water...26 TOPIC 3 Operating a pressurised irrigation system...27 Procedures for operating the system...27 Pre-start checks...28 Starting up the irrigation systems...28 Shutting down the irrigation system...29 Topic 3 Activity TOPIC 4 Operating a gravity-fed irrigation system...31 Plan irrigation activities and undertake pre-start checks...31 Start up the system (Operate the system)...32 Co-ordinate irrigation activities monitor system...32 Shut down the irrigation system...32 Topic 4 Activity TOPIC 5 Record irrigation activities...34 Topic 5 Activity Assessment...36 Contacts...37 Notes and comments...38 Appendix A - Unit of Competence...39 Appendix B - Glossary of Terms...40 Appendix C - Glossary of Units

5 Introduction This Learning Guide is a resource developed to support the implementation of the Nationally endorsed Irrigation Units of Competency. It is available in hard and electronic copy. This Learning Guide should be used with the proactive support of a qualified trainer. The trainer role may be provided by either: a workplace trainer the learner s supervisor and an off-site trainer employed by a Registered Training Organisation. It is not a distance-study resource to be used in isolation. On its own, this Learning Guide will not develop all the skills and knowledge required to gain competency in the unit of competence concerned. This Learning Guide has been developed to be used in conjunction with a trainer. Where this unit of competence fits This Learning Guide, when used as described above, will support the development of competence in the following units: RTE3611A RTE3610A Operate pressurised irrigation system Operate gravity fed irrigation system These units are 2 of 12 units that have been developed to facilitate training at level 3 (AQF3) and are highlighted below. Units of Competence RTE3611A RTE3610A RTE3606A RTE3607A RTE3608A RTE3605A RTE3604A Underpinning Knowledge RTE3609A BCS3147A RTE3601A RTE3603A Operate pressurised irrigation systems Operate gravity fed irrigation systems Measure irrigation system delivery performance Measure drainage system performance Monitor and operate water treatment processes Monitor and operate wastewater treatment processes Locate and replace faulty components in irrigation system Locate and clear blockages in irrigation delivery & drainage lines Apply principles of water management and hydraulics in irrigation work Operate fertigation equipment Connect irrigation system from drinkable water (potable) supply Install irrigation systems Install drainage systems 5

6 How to use this Learning Guide Your Role (the Learner) As the Learner in the irrigation industry, we expect you to take an active role in your training and development. We appreciate that balancing the pressures of work and development is a challenge and help and support will be at hand. It is your training and your future. We invite you to reap the potential benefits on offer to you by participating with enthusiasm and commitment. Understanding the competency unit At the back of this Learning Guide, you will find the competency unit that you will be assessed against. It is important that you take the time to read and understand what is expected of you. Your trainer will work through this with you before you start your training. Pay particular attention to the Evidence Guide where the skills you will be required to demonstrate (titled Demonstrated Ability ) and the background knowledge you should know (titled Underpinning Knowledge ) are listed. Your trainer will work with you and your supervisor to identify parts of the unit you already know (and will require assessment only) and which parts require additional training. The balance will depend on how long you have worked in the industry and your experience to date. Plan your training Once you, your trainer and manager/supervisor have agreed what you need to learn, your trainer will work with you and your supervisor to plan your training program. Your trainer will select the most appropriate activities and part of the Learning Guide for you to complete, and may even introduce new activities and handouts to support your particular needs. Make sure you know exactly which part of the Learning Guide and what additional activities you should be completing and by when. Complete the activities Your trainer may ask you to complete the activities in this Learning Guide as they are, or, they may customise them to make them more relevant to you in your workplace. They may also introduce new activities and practical demonstrations. Always consult your trainer before you attempt an activity to ensure that you are properly prepared. In many activities, your trainer or supervisor will need to demonstrate the task to you first, before you have an opportunity to practise under their supervision. Even if you think you know how to do something, always check with your trainer first. It is always possible that you may be doing something incorrectly. The successful completion of activities is also a great opportunity to gather evidence towards your assessment. At the end of each activity, ask your trainer for feedback. Understanding what you did wrong (and right) and why, is a critical part of learning. 6

7 Record your progress It is always encouraging to see that you are making progress, so use your copy of the competency unit at the back of this Learners Guide to tick off your completed tasks. Your Trainer s role Your trainer and supervisor will play an active role in the delivery of your training plan, but you should always ask them if you are unsure of what to do. Your trainer (or supervisor, under the guidance of a Registered Trainer) will: answer any questions you have about your training and how to approach it explain which parts of the Learning Guide and activities you should complete and when demonstrate the practical aspects of the Learning Guide and ensure you are fully prepared to complete activities safely and effectively supervise and guide you while you practice new skills and activities give you feedback on your progress and hints and tips on how to improve help you source and utilise references, workplace documents and materials help you prepare for your assessment and spot opportunities for gathering evidence towards your assessment. Assessment Ask your trainer to introduce you to your assessor at the beginning of your training and assessment program. You will need to work with your trainer and assessor to plan how you will gather evidence towards your assessment. References Your trainer will supply you with a list of reference you will need access to in order to complete this Learning Guide. Glossary of Terms and Units Please refer to Appendix B for Glossary of Terms and Appendix C for Glossary of Units. If you find any other words, terms or units that are unfamiliar to you, jot them down underneath the appropriate glossary and ask your trainer to explain them to you. Make a note of their meanings for future reference. Maintenance of this Learning Guide The irrigation industry is committed to ensuring that this Learning Guide is improved on an ongoing basis. As a result, your views and feedback on the effectiveness and content of this Learning Guide are important to us. IAA will be collating everyones feedback on a continual basis. Please take the time to pass on any ideas for improvement to your trainer. 7

8 Getting started This Learning Guide will help you to: Plan and co-ordinate irrigation activities for gravity fed irrigation systems Perform pre-start checks on pressurised and gravity fed systems Start up and inspect pressurised and gravity fed irrigation systems Shut down systems based upon irrigation indicators Record irrigation activities This Learning Guide will lead you through a series of topics. Each one begins by describing the skills and knowledge you will learn, and there is a tick box list to mark off as you go. In each topic you will be asked to complete associated learning and practice activities. These activities are tasks that will assist you to gain knowledge and skills. You should read the information notes, write answers to questions and do the practical exercises. There is no specific time limit for finishing this guide. It may only take a few hours to complete the learning activities but it may take days or weeks to fully gain the skills in the practice activities. Check with your trainer if you have any difficulties. How to use this guide The following symbols will be used to guide to ask you through the different learning and practice activities. Look out for them and complete the tasks as required. Read information about the topic. This will give you an understanding of the work, and why things are done the way they are. Complete the activity as directed. These will test your knowledge and give you practice at thinking about and doing the tasks involved. You will be alerted to hazards or risks associated with the work or activity by this symbol. Your trainer will show you... 8

9 Occupational health, safety and welfare Any work in the primary industries (agriculture, horticulture, irrigation) sector may be dangerous in some way. It is important to know about your workplace s occupational health and safety procedures. As an employee you have a responsibility to: follow your organisation s occupational health and safety procedures; follow manufacturers guidelines where available for machinery, tools and equipment; respond to a situation where someone is put at risk of injury provided that, in doing so, it does not endanger yourself; report any incidents or situations which cause yourself or other people injury, or put you or others at risk of injury; and follow legislative requirements Equipment and materials To help you complete activities, you will need access to the following: appropriate personal protective equipment a range of tools and equipment suited to the task Note: the tools and equipment required to complete this unit of competence should be readily available in your industry sector. It is the responsibility of the trainer (either on-job or off-job) to ensure that adequate tools and equipment are available for practice and assessment of the competencies associated with this Learning Guide. 9

10 1Soil/Plant/ Water Relationships PLANT /SOIL/WATER RELATIONSHIPS Is operating a planned irrigation system as simple as starting the system, letting it operate for a while and then turning it off? Normally, this is not the case! You have to think about aspects such as: What plants/crops are to be watered? How much water do they need to be productive? What is the weather like now and what is the forecast? How much moisture is in the soil already? What is the capacity of the irrigation system? In order to answer some of these questions, we shall start by looking at the water that plants need. PLANT WATER REQUIREMENTS Before you begin operating your irrigation system (regardless of the type of system), you need to consider how much water to apply to the plants. Water is required to dissolve plant food materials in the soil and transport them in the plant. It is a major component of cell sap and plant tissues. It is also essential for photosynthesis. Transpiration is an important factor affecting the quantity of water used by plants, because it influences the amount of moisture absorbed by the plant roots from the soil, and governs the rate at which water moves through the plant. Available moisture is lost from the plant root zone by transpiration and direct evaporation. As water is lost from soil, water moves from the lower soil levels, via capillary flow, to replace the moisture lost. However, this may not happen fast enough to meet the plants requirements, or the soil reserves may be too low to supply replacement water until after the next rainfall. Without irrigation occurring at the right time, the growth of the crop may be retarded and not be productive. The worst result is that the crop dies. 10

11 FACTORS AFFECTING PLANT WATER USE Apart from soil influences, there are other factors which affect the use of water by plants. These include: the plant species and the tolerance of the species to varying soil moisture conditions the rate of growth of the crop weather conditions depth of the root system. Plant species The amount of water each plant species requires to live, grow and produce a crop (whether the crop is leafy, flower, edible such as grain, vegetables, or other) depends on the requirements of that species. As a general rule, plants growing in moist situations in their natural conditions require a higher amount of water (on a day-to-day basis) than plants naturally growing in drier conditions. Rate of growth The greatest amount of water will be required when plants are establishing and growing rapidly in the early stages of crop production. As the rate of growth increases the plant s water requirements will increase, and then ease off as the plant matures. Weather conditions Weather is an important factor to consider as an integral part of an irrigation program. Weather conditions such as humidity, temperature, sunshine and wind all influence plant growth rates and moisture requirements. Weather patterns both past and present need to be monitored and recorded. Predicted weather should also be considered when planning an irrigation program. Information on the weather is readily available from a number of sources: news programs phone information newspapers computer programs records by self or previous operators weather bureau. Root depth The amount of soil water available to the plant depends on the depth of its root system and the density of active roots throughout that depth. Therefore, the effective rooting depth of the plant governs the volume of soil that can function as a water reservoir for the plant. Plants with deep root systems have access to a larger volume of soil, and therefore larger volume of soil water, than shallow rooted plants. Some examples of expected root depths for various plants under irrigation are shown in the following table. 11

12 Horticultural Crops Expected root depths under irrigation (m) Apple Apricot Banana Citrus Grapes Passionfruit Peach Pear Strawberry Vegetable Crops Expected root depths under irrigation (m) Bean Cabbage Carrot Cauliflower Cucumber Lettuce Pea Potato Tomato Field Crops Expected root depths under irrigation (m) Cotton Lucerne Maize Millet Pasture Soybean Sugarcane Sunflower Wheat Source: Cornish et al (eds) 1990 Irrigation for Profit: Water force Victoria, Irrigation Association of Australia, Numurkah. It is interesting to note that, although it is desirable for soil water to be made available to the whole of the root zone, crops (and individual plants) will survive quite well if only part of their root zone is wetted. This is provided that they receive an adequate water supply for the whole plant. 12

13 SOIL WATER PRINCIPLES Soil is made up of particles and pores (air spaces). When a soil is saturated with water, all of the air has been replaced with water. If the soil is then allowed to drain, some of the water moves out under the influence of gravity. When this gravitational drainage is complete, usually after a few days, the soil is said to be at Field Capacity (FC) or Drained Upper limit (DUL). The amount of water in the soil then starts to decrease because some will be absorbed by the plant roots and some will evaporate form the soil surface. Eventually when a situation is reached where plants are no longer able to extract water from the soil, the plants will wilt. When plants wilt during the day and do not recover at night, the soil is said to be at Permanent Wilting Point (PWP) or the Lower Limit (LL). The soil water that can be used by plants is known as Plant Available Water (PAW). PAW is the amount of water held in the soil between the FC and PWP. It is expressed as depth of water in mm per metre depth of soil. The amount of available water in the soil profile depends largely on the soil texture. The table below shows the effect of soil texture on PAW. Soil texture Approximate amount of available water in soil profile (mm/m) Sand 50 Fine sand 75 Sandy loam 110 Fine sandy loam 140 Loam 165 Silt loam 175 Light clay loam 175 Clay loam 165 Heavy clay loam 225 Clay 140 Source: Cornish et al (eds) 1990 Irrigation for Profit: Water force Victoria, Irrigation Association of Australia, Numurkah. As available water is used up, plants find it increasingly difficult to extract water against the forces holding the water in the soil. Water stress symptoms and subsequent decline in plant growth and yield usually become apparent when more than 50% of the PAW has been extracted. So, irrigation is normally timed to occur when 50% of the PAW has been used. This level of reduction in PAW is referred to as the refill point. The amount of water supplied is normally that amount required to bring the soil back to Field Capacity. Example: 5 year old grape vines Soil type: Loam Available water: 165 mm/m (from table above) Expected root depth: 0.80m (see previous table) Allowable water use: 50% = 0.5 Depth of irrigation: 0.5 x 165 x 0.8 = 66mm 13

14 While this example gives the depth of irrigation needed to bring the soil back to field capacity, it does not give any indication as to when this might be. The predicted or the actual rate at which soil moisture is being depleted needs to be determined. You should also note that the rate at which the irrigation water is being applied needs to match the rate at which the water is being taken into the soil surface, otherwise water may be lost as run-off. 14

15 Topic 1 Activity 1 Using the example above and a 50% depletion rate for available water, work out the depth of irrigation required for a crop on your enterprise for the appropriate soil type. Soil type: Available water: Expected root depth: Allowable water use: Depth of irrigation: Get your trainer to check your answers. 15

16 SOIL WATER MOVEMENT In order to calculate how much water a crop will need to keep it growing well and be productive, you need to understand some of the processes that affect water movement into, within and out of soil. These processes include: infiltration rate percolation Infiltration rate The rate of application of water to a surface, whether by irrigation or rainfall, is termed the precipitation rate. This rate is measured as depth in mm of applied water per hour. When water is applied to a crop, it will soak into the surface of the soil. The rate that the water soaks in is dependent upon the infiltration characteristics of the surface. The infiltration will vary, but is influenced by a number of factors including: consolidation and compaction of the soil surface soil texture and structure the amount and type of vegetation cover moisture status of the soil, that is, whether the soil is currently wet or dry. If water is applied at a rate faster than the infiltration rate of the soil, then water will either run-off or pond on the soil surface. Let s look at the implication of this for a three irrigation systems. Sprinkler irrigation It is undesirable to have run-off of irrigation water because it is not an efficient use of water. It can also contribute to undesirable wetting of the area surrounding the crop, be it paddocks or nursery areas. Excess water could run into drains or watercourses carrying wastes or pollutants. The maximum application rates preferred under sprinkler irrigation on level to undulating land are as follows: Sandy soils Medium loam Clays 30 mm per hour 15 mm per hour 5 mm per hour Drip irrigation Application rates should be sufficiently low that run-off does not occur. Flood irrigation In this type of irrigation, the amount of water applied at the upper end of the furrow or bay deliberately exceeds the infiltration rate. Water then flows down the gradient to irrigate the bay or furrow so flood irrigation application rates do not have the same meaning as with sprinkler irrigation. 16

17 Measuring the infiltration rate In the field, infiltration rate can be measured by using a ring infiltrometer. The infiltration rate is calculated as follows: The height the water level drops is divided by the time taken for that drop in level. height water drops time taken for the drop in level = infiltration rate For example, if the water level drops 40mm in two hours the infiltration rate would be: 40mm 2 hours = 20mm per hour Your trainer will show you a ring infiltrometer and explain how to use it to calculate the infiltration rate. 17

18 Topic 1 Activity 2 Measure the infiltration rate of water into two different types of soil. If you do not have access to an infiltrometer, you can use the following system. Insert a tin (with both ends removed) about 30mm into the surface of the soil being measured. Fill the tin with water and measure the height of the water above the soil surface. Record the time the water takes to be absorbed into the soil. For your two soils, calculate the infiltration rate for each. Soil Type 1 Soil type 2 Your trainer will know the infiltration rates for a range of soils. Use these to determine the soil types that you are working with. Which soil type do you have? Soil Type 1 Soil type 2 18

19 Percolation Percolation is the downward movement of water through the soil. The rate of percolation is determined by the: size, number and continuity of the pore spaces amount of moisture held in the pore spaces resistance given by trapped air. In sandy soils the percolation rates is higher than in clay soils and in fact water percolates readily through sand, sandy loam and loam. While this means that any applied fertilisers can be leached through the soil profile very quickly, it also means that these soils can be irrigated with water that is too salty for use on clay (heavier) soils. 19

20 2Calculating water requirements CALCULATING AVAILABLE WATER Irrigation is used to provide the optimum amount of soil water, so that the crop is growing according to plan. If excess water is applied, soils may become water-logged. Unnecessary costs associated with pumping and water allocations will also result. If crops are not supplied with enough water, the quality and quantity of yields could be reduced. It can be difficult to calculate exactly how much water needs to be applied to plants to replace losses due to plant transpiration and direct evaporation from the soil surface. There are many methods of estimating soil moisture, and each has its advantages and limitations. Initially, you may have difficultly assessing soil dryness and relating this to water requirements. However, as you gain experience you will find your soil moisture estimates will prove to be very reliable, and an essential part of good irrigation practices. You should make estimates before, during and after watering. Sampling or measuring for soil moisture must be done within the root zone of the plant. The surface soil must not be used as a guide to water requirements because the surface soil will dry out more quickly than that below and, if watering is based on the top 10mm, overwatering will result. The soil below the root zone will often remain wetter than that within the root zone and therefore, it should not be used as a guide to plant moisture requirements. Accurate and precise measurement of available water is important so that the crop is only watered as required. The need to conserve fresh water supplies is critical and irrigation operators have an obligation to ensure that water is not being wasted. In many areas it is an expensive commodity. In order to determine when to water and how much water to apply, you need to be able to measure and monitor the soil moisture levels. The various methods for calculating when and how much water should be applied to a crop can be grouped as follows: plant based methods soil based methods weather based methods 20

21 Plant based methods Appearance of plant This technique relies on observation of changes in the appearance of the crop. These changes occur in the colour of the plant, the hang of the leaves and the length of the internodes. Measurement of crop water status These methods use sophisticated techniques such as sap flow measurement, infrared photography and canopy temperature assessments. These techniques are mainly used for research proposes. Soil based methods By feel Experienced irrigators can tell the moisture content of their soil by feeling it. The soil sample should be taken from the depth of the greatest root concentration. The following table gives an indication of the soil moisture status based on feel. Percent available moisture remaining Coarse textured soils (sand based) Medium textured soils (silt based) Fine textured soils (clay based) Below wilting point Dry, loose, flows through fingers. Crumbly, easily broken down into powder. Hard, cracked, difficult to break down into a powdery condition Appears dry, will not form a ball. Crumbly but holds together under pressure. Forms a ball under pressure Almost forms a ball which breaks when handled. Forms a ball under pressure. Forms a ball, will ribbon out between thumb and forefinger Forms a weak ball which breaks when bounced in the hand. Forms a pliable ball but not ribbons. Easily ribbons out between thumb and forefinger, appears slick. 100 (Field Capacity) No free water appears when squeezed but wet outline left on hand, particles stick to fingers. Sticky, no free water appears when squeezed, wet outline appears on hand. Sticky, no free water appears when squeezed, wet outline appears on hand, can roll thin rods with fingers. Saturated (above Field Capacity) Free water appears when squeezed. Soil is sticky. Free water can be squeezed out. 21

22 Indicator spots Many garden beds, turf grass areas and crop areas have spots that dry before the rest of the area. By monitoring these areas, irrigators can start to water before the bulk of the crop is stressed. Footprinting This technique can be used in an urban situation particularly on turf. If a footprint compresses the grass only, not the soil, and the impression does not return to its original shape, you can assume that the turf area is too dry. Water needs to be applied as the soil is probably below 50% of Field Capacity. Soil Moisture Sensors More accurate measurements can be obtained using a range of soil moisture sensors. There are variety of soil moisture sensors available. These include: tensiometers moisture blocks neutron probe meters EnvirosScan capitance probe heat pulse probe time domain refractometer. Tests conducted by the Irrigation Association of Australia have found that significant water savings (up to 50%) can be obtained by using soil moisture sensors. Some systems are connected to computers which automatically switch on watering systems when soil moisture levels fall below an established level The placement of sensors in the area to be irrigated is important. Locations chosen should be representative of the soil type. When siting the sensors note if two or three sprinklers overlap or if an area is affected by wind or shade. In some situations two or more sensors may be needed per controller where variations in drainage or exposure exists, eg. under eaves or overhangs of roofs or lawn areas of varying soil types. One sensor should be placed in the dry area to control the valves in that section and the other to controls the valves in the wetter area. Your trainer or supervisor will show you how to monitor the soil moisture using soil moisture sensors from your enterprise. 22

23 Weather based methods Pan evaporation The various climatic factors that affect plant growth and plant moisture requirements also affect evaporation from the soil. The combined water lost by evaporation from the soil and the plant surface, plus the water lost through transpiration, is referred to as EVAPOTRANSPIRATION (ET). The rate of evapotranspiration determines how quickly soil water is used. This will, in turn, determine the amount of water that needs to be replaced by irrigation or rain. There are two common methods used to estimate the rate of ET in the field: measure the rate of evaporation from a standard evaporation pan and relate this to the ET of the crop measure the climatic factors which determine the rate of ET and calculate the rate of ET. The climatic factors to be measured are radiation, temperature, wind and relative humidity. The Bureau of Meteorology records daily evaporation in over 50 areas of New South Wales and ACT. These are often published in weather reports in the daily press. Water budgeting The water budget is started on the day after heavy rain or irrigation when the soil is at Field Capacity. The soil type is known and so the amount of available water at Field Capacity can be estimated. Daily evaporation values are subtracted from the total and any effective rainfall is added. A running total is maintained on a daily basis. When the total amount of available water falls below an established level, often 50%, then the area is irrigated. Your trainer will explain the use of a standard evaporation pan and will show you how to draw up a water budget if it is used in your enterprise. 23

24 Topic 2 Activity 1 You are required to determine the moisture content of a soil sample using the following soil based methods. By feel Using a soil moisture sensor The soil sample should be typical of the type of soil that your crops grow in. Compare the results of both these tests. 1. Which test is more reliable? 2. Which test was easier to do? 3. Which technique is used in your industry sector? 24

25 Topic 2 Activity 2 You are required to check the daily newspapers and see if the evaporation rates for your area are listed. If they are not available, you may need to contact the Bureau of Meteorology for the information. Over five continuous days, indicate the evaporation rates for your area. Write them down below. Time of year: EVAPORATION RATE Day 1 Day 2 Day 3 Day 4 Day 5 Your trainer will provide you with a list of evaporation rates for different times of the year. Compare these to those you have recorded. Discuss the differences with your trainer and indicate the changes in the timing and frequency of irrigation you may need to make at different times of year. 25

26 CALCULATING AVAILABLE WATER Once you know the moisture level in the soil, the soil type and the water requirements of the crop, you can determine how much water to add to the soil during an irrigation period. Your trainer or supervisor will show you how to test the soil for available water and calculate the amount of water required for a particular crop in your enterprise. 26

27 3Operating a pressurised irrigation system PROCEDURES FOR OPERATING THE SYSTEM Before you turn your system on, you need to know: how the system works how to shut it down how to input the control information How the system works The installer should have given you a plan of the system showing all the major components and the areas that will be covered by the emitters. Work through the plan of an irrigation system making sure that you understand how the system works. You should discuss the best approach to watering in windy areas or extremely dry areas, or you might need to have the operation of the syringe cycle on the system explained to you. The system should always be filled slowly in order to prevent unnecessary damage to pipes and fittings from pressure surge or water hammer. Shutting down the system The procedure for shutting down the system should also be explained and demonstrated. This may vary it could be as simple as pushing a button, to closing an electric or hydraulic valve, or stopping the operation of a pump. Putting in the control information With manual systems you simply put out the sprinklers and run them for the desired time, ensuring that you have a good even coverage of the area to be irrigated. However, if the system is automatic and has a controller installed, you will be required to input the irrigation information so that the system delivers the required amount of water to the crop. This information you have calculated from researching the water requirements of the particular crop and from soil moisture levels of the area to be irrigated. Irrigation system controllers vary in capacity, according to the size of the irrigation system. The controllers for home garden irrigation systems are normally quite small. Larger systems can be quite complex, requiring the information to be put into a computerised master controller, either directly or through a series of satellite controllers. 27

28 There are as many manufacturers as there are variations on the way in which a system is set up. With technology improving, the features of irrigation systems are constantly changing. It is extremely difficult to set down clear instruction on how to program a system because each one could be different and there are so many variables involved. However, with any system, it is important that: The information you have on the plants requirements is as accurate as possible. The supplier of the system gives a demonstration, along with the plans of the system layout and the necessary operator s handbooks to the operator. The system is updated according to the plant and crop requirements. This can only be done following an examination of the system when in operation, combined with an examination of the condition of the plant and soil moisture, taking into account the changing weather conditions. As automatic as irrigation systems may become, there is still no substitute for a handson practical approach to irrigation, that is, regular checks on the operation of the system and on the condition of your plants and soil moisture. Your trainer will show you a range of controllers and how to program them. PRE-START CHECKS There will always be pre-start checks that you need to make on your irrigation system. Checks of water, power, fuel and lubricants must be made to ensure that all are available and the control system is functional. Pumps will need to be primed as necessary and valves and controls are opened and closed as directed. Pressure and flow testing equipment may need to be calibrated. Refer to enterprise procedures and the operator s manuals for other pre-start checks that need to be undertaken. Your trainer will go through all the necessary pre-start checks for the system that you are using in your enterprise. STARTING UP THE IRRIGATION SYSTEMS Once all the pre-start checks have been completed, you can start up the system. The start-up sequence should be implemented in accordance with the operations manual. Once the system is fully operative and full pressure realised, check the system for: malfunctions leaks or blockages erosion. If any problems are located, they should be corrected or repaired immediately and all repair work should be reported in accordance with enterprise procedures. You should also check that the pressure at the headworks and control valves is within design specifications. If these are within specification guidelines, it will indicate that you have efficient filter operation and that the water will be distributed evenly to the targeted area with minimal wastage and run-off. 28

29 SHUTTING DOWN THE IRRIGATION SYSTEM The amount of time that the system operates will vary and depend upon the irrigation schedule and the prevailing weather conditions. Once required soil moisture levels have been achieved the system should be shut down. Depending upon the manufacturer s and enterprise specifications, the system may need to be drained. This is particularly important if you are using a portable system, because once the shut down is complete, the system may need to be stored or moved to another site. All drainage and treatment systems need to be checked in accordance with enterprise procedures. All irrigation activities should be recorded in accordance with regulatory requirements and enterprise procedures. 29

30 Topic 3 Activity 1 You are required to operate a pressurised irrigation system that is found in your industry sector. Answer the following questions, then demonstrate to your trainer or supervisor that you can undertake the activities associated with operating a pressurised irrigation system. Use the checklist below to make sure that you have done everything. Type of system Crop being irrigated Weather conditions Frequency of operation of system Amount of time system needs to be operating Check pre irrigation soil moisture levels... Pre-start checks of system water availability and quality... power... fuel and lubricants... prime pumps... valves opened and/or closed... Start up system implement start up sequence... monitor system for all malfunctions, leaks or blockages... check that water is being evenly distributed over targeted areas... check soil moisture levels... Shut down system... Check post irrigation soil moisture levels... 30

31 4Operating a gravity-fed irrigation system PLAN IRRIGATION ACTIVITIES AND UNDERTAKE PRE-START CHECKS In the same way that valves and fittings control water flow in pipes, there are various structures in channels that have a similar function. These include: gates to control the direction of flow of water checks and weirs to stop water flow and increase the height of the water level in the channel drop structures, where it is necessary to bring water to a channel lower in height culverts, where access roads are required to cross the channel. As part of the planning process for conducting gravity fed irrigation, you need to ensure that all these structures are in good working order. You should also check: the irrigation equipment and its availability for the allocated fields to be irrigated the availability of the water pumps, bores and other water delivery mechanisms. Once these are all in working order and in place, you should position pipes and syphons as required and in accordance with enterprise standards. The work crew should be briefed on the requirements of the irrigation activities to be undertaken and any other pre-start checks should be done before the irrigation activities start. These may include priming pumps, checking that there is sufficient fuel and lubricants available, and checking that gates and controls are in the correct position (either opened or closed, depending on the situation). 31

32 START UP THE SYSTEM (OPERATE THE SYSTEM) There are various methods of delivering the water from the channel into the head of the bay or furrow. These include: Syphons. The water level in the channel is higher than the soil level in the bay or furrow so it will easily siphon using plastic or aluminium tubes. Normally one siphon is used for each bay or furrow. The siphon is started manually at the start of the irrigation and the irrigation can be stopped by draining the channel or by removing the siphon. The use of syphons is labour intensive and costly, although larger diameter syphons are shifted and started by machines. Gates. Used with bays, a gate is opened in the wall of the channel. Pipe outlets. Also used with bays, a pipe is installed in the wall of the channel at the time of construction. A cap or plug is removed to allow water into the channel. In some intensive agricultural and horticultural applications, alternative distribution methods are common using low pressure pipelines. In the gated pipe system a pipeline is installed at the top of the field with gates allocated to correspond with each furrow. Various types of rigid and lay-flat plastic pipes are available as alternatives to channels in furrow irrigation layouts. In some applications, buried pipes with risers at each furrow head are used. You should note that there are many versions of the above techniques in use. The operation of the system will vary according to the water delivery mechanism, so you should check with your trainer and/or workplace supervisor to determine the specific enterprise procedures. Your trainer will demonstrate how each of theses water delivery methods work. CO-ORDINATE IRRIGATION ACTIVITIES MONITOR SYSTEM Once the irrigation activity has started, you should monitor the crew activities for efficient teamwork and provide the appropriate directions and instructions. The water levels in the ditches and channels must be monitored and maintained to provide sufficient head. There may be a number of fields to be irrigated. The operator must be aware of the schedule so that as one field is shut down, the next field is started. Any malfunctions to equipment, damage to water courses, blockages, seepage or leakage are corrected or repaired immediately and reported in accordance with enterprise agreements. If used, pumps are monitored during operation and rubbish is cleared from outlets. It may be necessary to backflush the filters and if this does need to be done, it should be done in accordance with enterprise procedures. If water reuse systems are used, they should be checked for clearance and freedom from weeds. SHUT DOWN THE IRRIGATION SYSTEM The time lag between shut down and end of watering is determined to minimise run-off and ensure deep percolation. Once irrigations activities have been completed, the system components should be shut down in sequence in accordance with the manufacturer s and enterprise procedures. This sequence will be different for each system and will depend on the type of water control devices your enterprise uses. Your trainer will instruct you in the specific techniques for a range of gravity fed irrigation systems. 32

33 Topic 4 Activity 1 You are required to operate a gravity-fed irrigation system that is found in your industry sector. Answer the following questions, then demonstrate to your trainer or supervisor that you can undertake the activities associated with operating a pressurised irrigation system. Use the checklist below to make sure that you have done everything. Type of system Crop being irrigated Weather conditions Frequency of operation of system Amount of time system needs to be operating Check pre irrigation soil moisture levels... Pre-start checks of system water availability and quality... power... fuel and lubricants... prime pumps... controls/gates opened and/or closed... pipes, system equipment and outlets are positioned and set up correctly... Start up system implement start up sequence... syphons or other delivery mechanisms are primed and started... monitor system for all malfunctions, leaks, damage to watercourses or blockages... check that water is being evenly distributed over targeted areas and adjust flow rates if necessary... head water levels are monitored and maintained and adjust flow rates if necessary... check soil moisture levels... Shut down system... Tailwater control systems are implemented... Check post irrigation soil moisture levels... 33

34 5Record irrigation activities RECORD IRRIGATION ACTIVITIES Regardless of whether your industry sector uses gravity fed or pressurised irrigation systems (perhaps it uses both types), you need to record the activities associated with each irrigation activity. The minimum information you need to record includes: specific activities of each member of the irrigation operation process and the hours for each the irrigation start and finish times the water storage levels for gravity fed irrigation systems recommendations for service and maintenance activities monitoring activities used to determine the amount of irrigation required data collection process, including those used to test the levels of soil moisture climatic data including rainfall, air temperature, frost risk other information such as water quality. This information may be recorded electronically or manually using a log book. it may also be appropriate to use graphs or charts to record some of the information. 34

35 Topic 5 Activity 1 Record two irrigation activities for either gravity-fed or pressurised systems using the record keeping logs from your enterprise or industry sector. If you do not have access to standard record keeping documents, your trainer will show you what type of information needs to be recorded and how to record it. Attach your records to this page of the Learners Guide. 35

36 Assessment Being Assessed Once you have completed all the activities in this Learning Guide, you will need to ask your workplace trainer or Coach to sign below. Review by workplace trainer/coach I have reviewed this Learning Guide and agree that the required activities have been completed to my satisfaction. Review by workplace trainer/coach I have reviewed this Learning Guide and agree that the required activities have been completed to my satisfaction. Signed:...Date... Name:... Address:......Telephone:... Congratulations! The completion of this Learning Guide will assist you to gain industry skills and will provide valuable evidence towards formal assessment for this unit of competency. Please record the completion of this Learning Guide in your competency Record Book. If you wish to have a formal assessment for this or other units of competency, you should contact a Registered Training Organisation to obtain details on your assessment options. 36

37 Contacts For further information on workplace assessment and training, please contact your state Industry Training Advisory Board: NSW Primary Industry Training Advisory Board (02) Rural Industries Training Advisory Board NT Inc (08) Queensland Rural Industry Training Council (07) Agricultural & Horticultural Training Council of SA (08) Tasmania Rural Industry Training Board (03) Victorian Primary Industry Training Board (03) Western Australia Primary Industry Training Council (08) Other contacts List below other useful names and numbers. 37

38 Notes and comments Use this space for any activities or any calculations you may have to do, or for attaching any forms you have been asked to collect. This is also a good spot to record thoughts and observations on this Learning Guide, and what you have been doing. 38

39 Appendix A Unit of Competence COMPETENCY STANDARDS In May 2002 the irrigation competency standards were in the last stages of review prior to endorsement. This page has been inserted to indicate that once these are available, the endorsed competency standard equivalent to unendorsed standard <insert number and name> should be inserted here. 39

40 Appendix B Glossary of Terms TERM DEFINITION application rate Rate at which water is applied to an area or crop, measured in centimetres per hour. aquifer Underground water-bearing layer of permeable rock, sand or gravel capable of yielding significant quantities of water to bores or springs. as-built drawing Plans of the actual location of the components of an irrigation system as installed. The plans are often not drawn to scale and are supplied by the installer. as-constructed drawing See as built drawing. Sometimes know as worker executed drawing. backflow prevention device Mechanical device located at the start of the irrigation system to prevent water flowing in the direction contrary to the normal or intended direction of flow. This device is used to prevent the possible contamination of potable water supplies. barometric pressure Atmospheric pressure at the altitude where it is measured. bore Hole of uniform diameter (usually 100 to 200mm in diameter) drilled vertically into the ground to tap into an aquifer. catchment Area of land from which rainwater or snow melt drains into a reservoir, lake or stream. check valve Device that prevents reverse water flow in pipes and sprinkler heads. contour Flow of the land. contour line Line drawn on a plan connecting all points of the same height above or below a specified datum point, often sea level. control valve Valve that controls flow of water to a section of the irrigation system. controller Electrically driven timing device capable of being programmed to switch on in sequence the remote control valves of an irrigation system to a preset schedule. delivery head Distance in height between the delivery point and the pump outlet. drainage Movement of water off or out of the soil. drippers Emitters releasing a small dribble or stream of drips at low pressure, measured in litres per hour. dynamic pressure Pressure in the irrigation system when it is operating, measured with water flowing through components that obstruct flow. EC Electrical Conductivity a measure of dissolved salts in water. emitter Device that delivers water onto the crop or area. evaporation Loss of water to the atmosphere in the form of vapour. evapotranspiration Loss of water resulting from both transpiration by plants and evaporation from the soil. fertigation Process whereby fertilisers are added to the crop via the irrigation system. field capacity Amount of water retained in a soil 24 to 36 hours after saturation by rain or irrigation. It represents the maximum amount of water in a soil available to plants. 40

41 TERM flow rate friction head friction loss gauge pressure head impact sprinkler impellor infiltration rate kpa lateral leaching master valve micro-irrigation moisture holding capacity operating pressure percolation permanent wilting point permeability ph DEFINITION Measure of the amount of water delivered, usually measured in litres per second or cubic metres per hour. Pressure loss due to friction measured in metres of head. Loss of pressure due to friction created as water contacts or rubs against the internal surfaces of irrigation system components. Friction loss increases with the roughness of the internal surface of pipes and fittings. Pressure measured by the gauge in a system and is the pressure above atmospheric pressure at the altitude where t is measured. Pressure in an irrigation system is measured in metres of head instead of kilopascals because it is easier to use in calculations. Sprinkler which rotates when a stream of water from the nozzle hits an oscillating knocker arm. Device in a pump designed to propel water in a specific direction. Rate at which precipitation falling on the surface of the soil moves into the soil below the ground surface. Kilopascals (a metric measure of pressure). Irrigation pipeline complete with watering devices controlled by a valve and fed from the main line. Removal of material by water eg water draining through soil can remove soluble soil components. Valve to control water from the source to valves and laterals. System of irrigation designed to use low pressure and small flows of water to mini-sprays, mini-sprinklers, drippers and piping with a series of small openings. Ability of a soil to hold water against the force of gravity. Pressure in an irrigation system at a given point when the system is operating efficiently. Movement of water through a root zone. Measure of soil moisture levels where plants can no longer extract water from the soil. Ability of a substance eg soil or rock, to allow water to pass through it. Measure of acidity or alkalinity of a substance eg water or soil, on a scale from 0 to 14. A ph of less than 7 is acidic, 7 is neutral, and more than 7 is alkaline or basic. poly pipe Pipe made from polyethylene. polyethylene Plastic material used to make flexible irrigation pipes and fittings usually black in colour. polyvinylchloride Plastic material used to make semi-rigid irrigation pipes and fittings usually white in colour, often referred to as PVC. potable Term used to describe water suitable for human consumption. precipitation Water falling from the atmosphere as rain, hail or snow, or from sprays or sprinklers. precipitation rate Rate at which water from the atmosphere falls onto the ground. pressure gauge Gauge used for measuring pressure. pressure head Operating pressure in metres of head required at the emitters. pressure loss See friction head. pressure reducing valve Valve used to reduce the pressure in a system. priming Technique used to fill a pump with water prior to operation. psi Pounds per square inch (an imperial measure of pressure). 41

42 TERM PVC riser run-off salinity saturation point solenoid solenoid valve solvent sprinkler static pressure static head stuffing box suction head suction lift tensiometer DEFINITION See polyvinylchloride. Pipe extension to raise the level of a watering device or emitter to an appropriate height for efficient water application. Any precipitation source that is unable to percolate into the soil and flows over the surface of the soil following the natural fall of the ground. Presence of salts in soil or water, in sufficient quantities to be harmful to plants. Point at which all the air spaces in a soil have been replaced with water. Coil of tubular wire producing a magnetic field. Valve operated or regulated by a solenoid. Chemical used to dissolve the outer surface of PVC pipe and the inside of PVC fittings so that they can be welded together. Emitter used to deliver water as a spray onto a crop or area. Amount of pressure available to operate an irrigation system measured with no flow in the system. Difference in height between the surface of the water source and the delivery point. Device on a pump that prevents water escaping from the body of the pump where the shaft emerges. Pressure from the weight of the water when the pump is below the water level of the water source. It is measured in metres of head ie distance from pump to water level. Occurs when the pump is above the water level of the water source. It is measured in metres of head ie the vertical distance the water has to be raised by the pump. Device used to measure the water content of soil by measuring the tension with which the water is held in the soil. total head Sum of all the head pressures that will affect the performance of the pump in an irrigation system. total dissolved solids (TDS) Measurement of the total amount of slats dissolved in water. It is a measure of salinity. total static head transpiration turbidity valve water hammer water velocity watertable vacuum velocity of water wilt Difference in elevation (measured in metres) between the water source and the point of discharge. Loss of water as vapour from the leaves of a plant. Measure of the amount of suspended particles in water. Device inserted into an irrigation system to regulate flow or pressure. Knocking sound in pipes caused by vibration due to rapid increases or decreases in pressure due to fast closing valves. Speed of water passing a given point in an irrigation system. Level below the ground surface at which the soil is saturated with water. any pressure below atmospheric pressure ie a negative gauge pressure Speed or rate of water flow. Condition of a plant when transpiration losses are greater than water replacement through the roots. 42

43 Appendix C Glossary of Units UNIT CONVERSION TABLE The conversion equivalents are generally based on A.S In some instances the degree of rounding off has been adjusted for practical use. Length millimetre centimetre metre inch foot yard mm cm m in ft yd kilometre = 1000 metres = miles 1 mile = metres = kilometres Area square square square square square square millimetre centimetre metre inch foot yard mm 2 cm 2 m 2 in 2 ft 2 yd x x x x x x x x x x acre = m 2 = hectare = 1 x 10 4 m 2 = acre Volume cubic cubic cubic cubic cubic cubic millimetre centimetre metre inch foot yard mm 3 cm 3 m 3 in 3 ft 3 yd x x x x x x x x x x x x x x x x

44 Mass kilogram pound hundredweight tonne ton U.S. ton kg lb cwt t sh ton x x x x Liquid Measure cubic metre litre millilitre Imp gallon U.S. gallon cubic foot m 3 L ml Imp gal U.S. gal ft x x x x x Velocity 1 U.S. Barrel = 42 U.S. gallons (petroleum measure) = Imp. Gallons = 0.159m 3 1 litre = 1 x 10 6 mm 3 = 1 x 10 3 cm 3 or 1 cubic decimetre (1dm 3 ) 1 litre = 1.76 U.K. pints = U.S. pints. metre per foot per metre per foot per kilometre mile second second minute minute per hour per hour m/s ft/s m/min ft/min km/h mile/h Volumetric rate of flow litre per litre per cubic metre cubic foot cubic foot Imp. Gallon U.S. gallon U.S. barrel second minute per hour per hour per minute per minute per minute per day US barrel/d L/s L/min m 3 /min ft 3 /h ft 3 /min Imp gal/min U.S.gal/min (petroleum)

45 Pressure Head newton kilopascal bar kilogram pound foot of metre of millimetre inch of per square force per force per water water of mercury mercury metre square square centimetre inch Nm 2 (Pa) kpa bar kg/cm 2 lb/in 2 fth2o mh2o mm Hg in Hg x x x x x x x Power 1 Pascal equals 1 newton per square metre (1Pa = 1N/m 2 ) 1 mm Hg is also known by the name torr The international standard atmosphere (1atm) = pascals or bar This is equal to kgf/cm 2 or lbf/in 2 1 millibar = 100 pascal (1 mb = 100 Pa) Watt kilogram force Metric foot pound force Horsepower metre per second horsepower per second W kgf m/s ft lbf/s hp x x watt = 1 joule per second = 1 newton metre per sec. Decimal Multiples and sub-multiples of S1 Units Factor Name Symbol Example 106 mega M ML = megalitre (1 million litres) 103 kilo k kg = kilogram (1 thousand grams) 102 hecto h hl = hectolitre (1 hundred litres) 10-2 centi c cm = centimetre (1 hundredth of a metre) 10-3 milli m ml = millilitre (1 thousandth of a litre) The information in this Glossary of Units has been reproduced from the Australian Pump Technical Handbook with the permission of the Australian Pump Manufacturers Association Ltd. 45