IRRIGATION LEARNING GUIDE. Irrigation auditing. Supports learning against competency unit. AHCIRG501A Audit irrigation systems

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1 IRRIGATION LEARNING GUIDE Irrigation auditing Supports learning against competency unit AHCIRG501A Audit irrigation systems

2 NSW Department of Education and Training (DET) 2004 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, or 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. ACKNOWLEDGEMENT This work has been produced 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. PROJECT TEAM Alison Carmichael and Chris Rolfe, Naturally Resourceful Pty Ltd Contributors Dick Gordon, Waterwise Irrigation Services Hugh Barrett, Barrett and Associates CRC for Irrigation Futures: Myo Win and Hugh Campbell, Charles Sturt University and Helen Fairweather and Michael Grabham, NSW Agriculture Project Steering Committee Jolyon Burnett, Irrigation Australia Nitasha Thompson, NSW Department of Education and Training Helen Fairweather, NSW Agriculture Bruce Sutton, University of Sydney Tony Audley, Rural Training Council of Australia CONTACT Irrigation Australia PO Box 863, Mascot, NSW1460 P training@irrigation.org.au 2

3 CONTENTS GETTING STARTED Aims Scope Occupational health, safety and welfare DATA COLLECTION Irrigation water use Water quality Crop yield and quality Soil structure Nutrient status of the soil and crop Fertiliser and chemical use Drainage and environmental impacts Climate Soil moisture Irrigation system performance Management decisions Topic 1 Activity DATA ANALYSIS Water usage versus harvest results Soil and plant health versus harvest results Fertiliser applications versus crop yield, leaf and soil analysis Irrigation system performance Drainage and environmental impacts Seasonal summary Topic 2 - Activity SEASONAL EVALUATION REPORT Topic 3 - Activity RESOURCES FEEDBACK

4 GETTING STARTED AIMS This competency standard covers the process of collating and assessing system performance data, and compiling a system evaluation report including recommendations for improvements. On completion of this learning guide the learner will be able to: Collect and collate all available data. Assess actual data against benchmarks, specifications and predictions. Compile a report of system evaluation. Recommend alterations to irrigation system to achieve performance improvement. SCOPE The irrigation systems that are relevant to this guide may be pressurised irrigation systems such as micro-irrigation systems, spray irrigation systems or gravity fed irrigation systems. Micro-irrigation systems include mains pressure, low pressure, below or above ground, spray systems, drippers and inline drip systems and mini-sprinklers. Spray irrigation systems include travelling irrigators (soft hose, hard hose boom type) centre pivot, linear move, powered side roll, hand shift, permanent (installed) and bike shift/k-line systems. Specialist systems including bottom-watering systems for nurseries and greenhouse crops. Gravity fed irrigation systems include border check, contour irrigation and furrow irrigation. Irrigation systems may range from manual operation and monitoring to fully automated with computer control and monitoring. OCCUPATIONAL HEALTH, SAFETY AND WELFARE OH&S issues are not specified in this guide. It is expected that your trainer and/or your employer will help you to identify the hazards that you may encounter whilst undertaking tasks relevant to this learning guide and the appropriate management practices and reporting processes to mitigate the risks. These include hazards to health and safety, risk assessment procedures and implementation of risk control measures, safe operation of machinery and equipment, safe manual handling procedures, selection, use and maintenance of relevant personal protective clothing and equipment, safe procedures for working at heights and for outdoor work, including protection from solar radiation, dust and noise. 4

5 DATA COLLECTION An irrigation system commands a high capital and management investment without proper measurements of the inputs and outputs it is difficult to determine whether this time and money is well spent. Now that water can be bought and sold either permanently or seasonally on the open market it is easier to quantify the value of irrigation to a particular enterprise and whether it would be better to sell or lease the water entitlement rather than to continue using the water for irrigation. All irrigation systems have an impact on their local environment, and need to be monitored and assessed against the local environmental regulations. No two irrigation seasons are the same. By measuring and recording the significant inputs and outcomes for each season you can ensure that the positive outcomes occur more often and the negative outcomes can be minimised in successive seasons. Each irrigation enterprise and irrigation season will have its own unique set of inputs and returns that need to be assessed and while there will be some commonality in similar enterprises the audit will be need to take into account the uniqueness of each business. It is becoming a well-worn cliché. If you don t measure it, you can t manage it. The following is a list of inputs and returns that should be measured and recorded to allow a full evaluation of a given irrigation project: Measure and record irrigation water use. Test and record the quality of the irrigation water. Record the yield and quality of the crop or turf cover. Monitor and record the state of soil structure. Test and record the nutrient and chemical make up of the soil. Record the fertiliser and chemical use. Monitor and record the drainage and environmental impacts of the irrigation system. Record details of the climate throughout the season. Monitor and record the soil moisture status in the effective rootzone of the crop. Measure and record the irrigation system performance. Record the maintenance schedule for the irrigation system as it occurs. Record your management decisions taken throughout the season. IRRIGATION WATER USE All irrigation systems should be equipped with water meters to measure the water used over a given time. These meters should be read regularly and the usage recorded. This can later be collated with the climate and crop data. An accurate record of monthly and seasonal water use will make water budget planning and ordering a simpler task. A record sheet should be prepared and protocols put in place as to who will do the recording and when. WATER QUALITY Water quality changes regularly and can be affected by flow rates, climate and other outside influences. The results of a full water test should be held on file and regular monitoring of the EC and ph should be undertaken and recorded. If these readings vary greatly then a full water sample should be considered to track the cause of the variation before it affects plant health. A record sheet should be prepared and protocols put in place as to who will do the recording and when. 5

6 CROP YIELD AND QUALITY The various phases of the phenological crop cycle should be observed and recorded. This will include such events as sowing, germination/bud burst, flowering and harvest times for each crop as well as the yield and quality. Each crop has its own significant events that should be measured. For example fruit sizing rings are often used on stonefruit to monitor growth patterns; grapes have three distinct growth phases each being important in the final fruit quality. These phases can be more important in the final analysis than just the harvest details of yield and quality as they can be indicators of why a good or poor quality or yield has been recorded. Draw up a list of the important events in your crop cycles and prepare a record sheet and decide who will record these events and when. SOIL STRUCTURE The soils of the irrigation area should have been classified prior to the irrigation installation. If this has been done then the following irrigation characteristics should be available: Its classification, texture and structure (including restrictive layers). Depth of each soil layer (horizon). Electrical conductivity (EC) of each soil layer. Depth of the rootzone. Slaking and dispersion (from Emerson aggregate test). Estimate of the total available water and surface infiltration rates. Estimated readily available water for the current and proposed crops. Any seasonal or permanent groundwater. It is useful to monitor the state of the soil structure each season to ensure that soil health is either being maintained or improved. Soils with poor structure have an imbalance in pore proportions, with few large pores and a predominance of very fines pores. Poor soil structure is often very obvious to the eye showing a clear difference between compact, hard soil and soft friable soil. Crusting and hard setting are examples of poor soil structure. Water logging can also be an indicator of poor structure. An indication of the structural quality of the soil can be obtained by examining the shape, size and hardness of the visible aggregates or peds. Soils without a well-defined arrangement of aggregates are called apedal. The most favourable peds are granular or crumbly, polyhedral and fine blocky peds particularly if they have rough porous faces. Peds which indicate poor soil structure are coarse blocky and prismatic, especially if they have smooth faces. Platey structure indicates compaction. The worst soil structural condition is very coarse blocky or prismatic peds and massive hard structureless clay. The distribution of roots and their appearance can often reflect soil structure. Shallow depths, marked horizontal growth habits, gaps in the root profile or poorly developed roots that are deformed or unhealthy can be indicators of the effects of poor soil structure. NUTRIENT STATUS OF THE SOIL AND CROP Annual nutrient soil tests and leaf analysis in permanent crops should be taken at the appropriate time and recorded. FERTILISER AND CHEMICAL USE Records should be available of the types, rates and timing of various fertiliser and chemical applications to the irrigation fields. 6

7 DRAINAGE AND ENVIRONMENTAL IMPACTS Surface drainage should be channelled into an appropriate location to minimise any environmental impacts. In surface irrigated fields tailwater should be collected and reused. Some stormwater may also be collected for reuse. In pressurised systems there should be insignificant irrigation runoff with the exception of nursery and intensive vegetable and cut flower production. This high nutrient water should be collected and either reused or treated before disposal. Where there is potential for elevated watertables (eg. under surface irrigation systems) it is usual to install a number of observation test wells throughout the irrigation area. If the watertable is close to the surface then subsurface drainage may be required. It is normal to monitor the saturated level and the quality of water in this zone over the irrigation season. As a guide: If there is no watertable then read the wells at the end of winter, after heavy rain or after irrigations in the spring. If there is water at the bottom of the wells during the season, monthly readings are recommended. If the watertable is within a metre of the soil surface the reading should be taken and recorded twice weekly or weekly after irrigation or rainfall to determine if subsurface drainage is required. CLIMATE If an automatic weather station is installed then all relevant weather details should be held on a computer. If there is no automatic recording system then rainfall and other important events such as frost, extreme high temperatures, hailstorms and storm events should be measured and recorded. SOIL MOISTURE If soil moisture measuring equipment is installed, the readings taken throughout the season should be recorded. If there is no soil moisture instruments installed then obvious field observations such as crop moisture stress and water logging should be recorded throughout the season. IRRIGATION SYSTEM PERFORMANCE You may engage an irrigation specialist to measure and report on the performance of the existing irrigation system. They should undertake the following activities. Pressurised systems Pumps. For each pump, list details and record operating pressures for each irrigation station. Advise on the suitability of each pump for the range of duties required and calculate the flow to each station. Measure impeller wear of rotodynamic pumps by recording shut-off head. Measure suction losses and calculate efficiency of pumping system. Filters. Record the type and size of the filter unit. Comment on type and capacity of the unit and how it suits the flow rates and water quality. 7

8 Record the backflushing frequency and maintenance carried out on unit. Blocks. For each block note valve size, number of emitters, sprinklers or outlets and the operating pressure set at the valve. Emitters. Record sprinkler or dripper details providing details on jet sizes, rated discharges and operating pressures. Measure the application distribution with a series of catch cans and calculate the mean application rate, application uniformities for each irrigation block or the range of duties with mobile sprinkler systems. Operation. Record the current irrigation schedule for each block including the block area and the daily irrigation timings with whatever season variations that have been adopted. Report on the constraints of the business. Maintenance. Record the current maintenance schedule and the methods currently used to monitor the performance of the system. Comment on the suitability of the current maintenance schedule for the range of irrigation equipment being used. On completion of the system evaluation the irrigation specialist will be able to comment on the suitability of the equipment, operation and scheduling and monitoring and maintenance procedures to provide an efficient system for the crops and business. Surface irrigation systems Pumps. List details of each pump and operating pressures recorded for each duty. Advise on the suitability of each pump for the range of duties required and calculate the flow to each station. Measure impeller wear of rotodynamic pumps by recording shut-off head. Measure suction losses and calculate efficiency of pumping system. Delivery system. Describe the channels and piping systems with measurements for grade, freeboard and head loss through the structures. Measure the condition of the channels, the seepage losses and the command over each field. Outlets. Describe the number and size of the outlets Calculate or measure the flow rate in each. Fields. Describe each field detailing the bay or furrow size and length and the area of the field, together with the method of supplying the field from the channels (ie size and number of syphons). Record infiltration depths, extent of waterlogging, time it takes water to travel the full length of the field, duration of irrigation and drainage for each field. Calculate the distribution efficiency and assess uniformity of water application. Operation. Describe the current irrigation operation. This will include the number or hours to irrigate each field, the days to meet total farm crop water requirements, maximum daily pumping rates, the times and practices and the pumping costs/megalitre. 8

9 Assess the infiltration opportunity times with the advance and recession times to provide a best operation for each field. (Optimal flow rates and shut off times for various growth stages of the crop and time in the irrigation season). Describe the method of monitoring crop water use and the scheduling system currently used. Maintenance. Recoord the current maintenance schedule together with the methods currently used to monitor the performance of the system. Comment on the suitability of the current maintenance schedule for the range of irrigation equipment being used. Assess the system s capacity to meet the crop water needs and determine the overall water use efficiency and the field application efficiencies of the system using the current irrigation management practices. Make recommendations for changes and improvements if required. MANAGEMENT DECISIONS As part of the operation of the irrigation system, various management decisions will have been made throughout the season. These should be recorded so that they can be evaluated at the end of the season with all other measured inputs and outcomes. 9

10 TOPIC 1 ACTIVITY 1 You are the manager of a large horticultural development. Develop a recording schedule and procedures for staff using the headings listed in the topic including: Water quality Yield and quality of crop State of soil structure Nutrient status of soil and leaf Use of fertiliser and chemicals Drainage and environmental impacts of the irrigation system Seasonal climate Irrigation system performance Irrigation scheduling Seasons management decisions. Discuss your recording schedule and staff procedures with your trainer or group. 10