IRRIGATION L E A R N I N G G U I D E Operate irrigation systems Supports learning against competency standards AHCIRG305A Operate pressurised irrigation systems AHCIRG304A Operate gravity fed irrigation systems Developed by Irrigation Australia with funding from NSW Department of Education and Training
L E A R N E R S G U I D E Operate irrigation systems Supports learning against competency standards AHCIRG305A Operate pressurised irrigation systems AHCIRG304A Operate gravity fed irrigation systems Name Address Phone Fax
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 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 Australia PO Box 863 Mascot, NSW 1460 Tel: (02) 8335 4000 Fax: (02) 8335 4099 Email: jtraining@irrigation.org.au Website: www.irrigation.org.au 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
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 1...15 Soil water movement...16 Topic 1 Activity 2...18 TOPIC 2 Calculating water requirements...20 Calculating available water...20 Topic 2 Activity 1...24 Topic 2 Activity 2...25 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 1...30 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 1...33 TOPIC 5 Record irrigation activities...34 Topic 5 Activity 1...35 Assessment...36 Contacts...37 Notes and comments...38 Appendix A - Glossary of Terms...39 Appendix B- Glossary of Units...42 4
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: AHCIRG305A AHCIRG304A 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 AHCIRG305A AHCIRG304A AHCIRG303A AHCIRG303A AHCWAT301A AHCIRG306A AHCDRG303A Underpinning Knowledge AHCNSY307A BCS3147A AHCIRG302A AHCIRG204A 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
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
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 A for Glossary of Terms and Appendix B 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. IAL will be collating everyones feedback on a continual basis. Please take the time to pass on any ideas for improvement to your trainer. 7
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
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
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
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
Horticultural Crops Expected root depths under irrigation (m) Apple 0.75-1.20 Apricot 0.65-1.30 Banana 0.30-0.60 Citrus 0.60-1.20 Grapes 0.45-0.90 Passionfruit 0.30-0.45 Peach 0.60-1.20 Pear 0.75-1.20 Strawberry 0.30-0.45 Vegetable Crops Expected root depths under irrigation (m) Bean 0.45-0.60 Cabbage 0.45-0.60 Carrot 0.45-0.60 Cauliflower 0.45-0.60 Cucumber 0.45-0.60 Lettuce 0.15-0.45 Pea 0.45-0.60 Potato 0.60-1.00 Tomato 0.60-1.20 Field Crops Expected root depths under irrigation (m) Cotton 0.60-2.00 Lucerne 0.60-2.00 Maize 0.60-0.95 Millet 0.30-0.60 Pasture 0.30-0.60 Soybean 0.45-0.75 Sugarcane 0.45-0.75 Sunflower 0.45-1.20 Wheat 0.75-1.00 Source: Cornish et al (eds) 1990 Irrigation for Profit: Water force Victoria, Irrigation 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
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 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
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
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
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
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
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
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