Save water and money irrigate efficiently

Transcription

1 A guide to improving irrigation efficiency that can help increase farm profits, assist abstractors to meet Environment Agency requirements for licence renewal, and demonstrate sustainable use of resources for supermarket grower protocols. Save water and money irrigate efficiently

2 Irrigation efficiency matters Are you irrigating efficiently? How do you know? Can you justify it? Or is it just an instinct that you have about the way you manage your irrigation system? In future gut feelings will not be enough. You will need to quantify and demonstrate efficient use of water if you wish to renew an abstraction licence. This may include an irrigation water audit to show how effectively you use irrigation water on your farm. Irrigation efficiency matters because water resources, particularly in East and South-east England, are under severe pressure from increasing demands from all sectors, including agriculture. There is growing pressure from the government and public for all abstractors to use our limited water supplies as effectively as possible. Following the introduction of the Water Act 2003 abstractors are expected to demonstrate efficient use of water as part of the abstraction licence renewal process. All irrigation abstractions, whether for agriculture, horticulture, amenity and landscape or sports-turf are affected. Irrigation efficiency is simply about putting the right amount of water onto crops in the right place at the right time with minimal wastage. Most farmers are already aiming to do this as they know it makes sense both commercially and environmentally. But to demonstrate efficiency you will need to go beyond simplistic statements of intent, and inventories of equipment and management procedures. The onus will be on you to monitor your patterns of water use by collating relevant information to support and justify actual need. You will need to audit irrigation water use in much the same way as you audit farm accounts to the satisfaction on an independent accountant. This guide will help you to understand what irrigation efficiency means, the implications of irrigation water auditing, and the steps you will need to take to establish a water audit appropriate to your farm irrigation system. Environment Agency tests for abstraction licence renewal Test Objective Definition Responsibility 1 Continued To assess whether the continued Environment environmental abstraction can be sustained without Agency sustainability significant impact on water resources, other water users or the environment. 2 Continued To assess whether the abstraction is Individual justification still required based on the reasonable abstractor of reasonable need of the licence holder, and to check need that the maximum levels of abstraction are still reasonable. 3 Efficient use To assess whether the right amount of Individual of water water is being used in the right place abstractor at the right time. Source: Environment Agency 02 Save water and money irrigate efficiently

3 A commitment to improving irrigation efficiency L F Papworth Ltd manages 4,000 acres of farmland for 20 different landlords in North Norfolk. In 2007, they received a commendation in the Environment Agency's Water Efficiency Awards. Their aim was to reduce groundwater abstractions for irrigation, achieve more uniform irrigation application, reduce energy costs and train staff in good irrigation management. Cambridge University Farm helped to improve their irrigation scheduling with detailed weekly computer analyses of crop growth and water use, and Cranfield University carried out an irrigation water audit. Both provided us with invaluable information to help us understand the water needs of the crops, how to set priorities for irrigation and establish more accurate recording of rainfall and evaporation said Tim Papworth. This study was undertaken by Cranfield University and funded by the East of England Development Agency. Case study An irrigation water audit In summer 2006, several irrigation water audits were undertaken on potato farms in East Anglia as part of a study on water efficiency. The audits were based on normal irrigation practices on each farm. Information was gathered on local weather (daily rainfall and evapotranspiration), metered water use, and the costs and benefits of irrigation. This was used to compare scheduled and metered water use, to determine reasonable seasonal water need over several years, and assess the relative financial value of irrigation water. Seasonal water use Reasonable need Costs and benefits Irrigation water (mm) Scheduled irrigation Actually applied Farms Farms Water applied (mm) Water applied (mm) Agroclimate index (mm) Value of of water ( ( per per m 3 ) ) Cost Net benefit Benefit Farms Farms Indicates a close match between scheduled and metered water use. Demonstrates a clear link between climate variability and irrigation water use. Indicates the benefit farmers would lose if a total irrigation ban was imposed, or if their resources were inadequate. Save water and money irrigate efficiently 03

4 The pathway to efficiency There is no one quick-fix to irrigate efficiently. Think about irrigation efficiency as a goal the things you need to do are steps along a pathway towards that goal. There are many things to consider and the importance of each will depend on your particular circumstances. The pathway to irrigation efficiency The pathway demonstrates that an irrigation system is made up of several inter-linked components that all play a vital role in achieving efficient irrigation. It also breaks down the irrigation system into its component parts so that each can be separately examined to ensure that it is working as expected. Understand your system Optimise performance of your irrigation network and equipment Optimise your soil and water management practices Demonstrate best practice Efficient irrigation 04 Save water and money irrigate efficiently

5 Irrigation management a crucial factor An Australian study showed that more sophisticated irrigation systems and scheduling tools do not necessarily lead to better irrigation performance. A key factor was always the management skill of the irrigator. Demonstrating best practice Rate irrigation highly within your management system Know your soils from an irrigation perspective Design and maintain irrigation systems correctly Monitor all aspects of each irrigation event Use objective monitoring tools to schedule irrigation Use more than one method to schedule irrigation Retain control of irrigation scheduling Remain open to new information Understanding your system This is the critical starting point on the pathway and is the key to getting the best out of your irrigation equipment and your soil and water management practices. Try the 5-minute Irrigation Performance Assessment on the next page to see how well you really understand your system. Optimising your irrigation network and equipment This means focusing on three key areas pressure, water use and uniformity. The most widespread problem is low pressure, often the result of extending irrigation schemes without paying sufficient attention to the impacts of increased demand on pump capacity, the distribution network and equipment performance. The result is poor application uniformity with knock-on effects on crop yield and quality. Regular checks are needed on pressure and volumes of water delivered to particular fields for comparison with manufacturer s guidelines for pumps and in-field equipment. In-field tests using catch-cans can be used to check that correct equipment settings (e.g. sector angle, lane spacing etc), water pressures and flow rates are being translated into a uniform application of water across the field. Optimising your soil and water management practices This hinges on ensuring that water applications are managed (scheduled) according to crop water requirements without unnecessary waste, avoiding over-irrigation and/or surface run-off. Most irrigators still rely on gut feeling to determine when it is right to irrigate, usually by walking the crop and taking soil auger samples. However, pressures from supermarkets (grower protocols) combined with the requirement to demonstrate reasonable need at abstraction licence renewal will inevitably force growers to adopt a mix of both subjective and more scientific scheduling techniques. Demonstrating best practice The final step on the pathway is to demonstrate best practice. Some of the best practices that have proved over time to lead to more efficient irrigation are listed in the box above. Save water and money irrigate efficiently 05

6 How well do you think you are irrigating? As a first step towards improving your irrigation efficiency, try this 5-minute Irrigation Performance Assessment. It is subjective but it will help you to assess how well you are irrigating and identify opportunities for improvement. For each question, circle the answer that best fits your situation. Then add up your score and refer to the box below to rate how well you are performing. Q1. Do you have enough water in a season to meet your total crop irrigation demand? 2 Inadequate volume 3 Adequate in an average year 4 Adequate in all years Q2. Can you abstract enough water to meet your crop water requirements in a peak month? 2 Inadequate volume 3 Adequate in average year 4 Adequate in all years Q3. Do you have a strategy for managing periods of limited water availability/restriction? 1 No plan 2 Limited consideration 3 Some consideration 4 Detailed strategy Q4. How efficient is your on-farm storage and distribution system? 2 OK 3 Good 4 Excellent Q5. Does your irrigation system (e.g. gun, boom) operate at its design pressure in each field? 2 No 3 Yes, in most fields 4 Yes, in all fields Q6. How uniformly does your system apply irrigation water within the field? 2 Large variations 3 Some variation 4 Only minor variations Q7. Do you know the rate of water applied (e.g. m 3 / hr) by your system? 2 Based on manufacturer s information only 3 Measured some time ago 4 Measured routinely Q8. What is the current physical condition of your pumping, distribution and application system? 2 Major repairs required 3 Minor repairs required 4 No repairs required Q9. Do you compare your crop returns (yield) against the volume of water applied? 1 Not measured 2 At farm level only 3 Sometimes at field level 4 Routinely at field level Q10. Do you use a scientific tool (e.g. neutron probe, computer model etc) to schedule your irrigation applications? 1 No, visual inspection only 2 Scientific tool on some crops 3 Scientific tool on all crops Q11. Do you modify your irrigation applications in response to forecast weather conditions? 1 No 2 Sometimes 3 Usually 4 Always Q12. What is the quality of the water you use for irrigation? 2 Marginal 3 Satisfactory 4 Good Q13. Do you think you would save water by becoming more efficient? 1 Yes, definitely 2 Maybe 3 Don t know 4 No Now add up your score to assess your opportunity to improve irrigation efficiency: Score: 0 17 Major Moderate Minor If your score is low then revisit the questions to see where you can best make improvements to your irrigation system and management practices. 06 Save water and money irrigate efficiently

7 Is trickle more efficient than sprinklers? Potentially yes but in practice it all depends on how well it is managed. A good manager can operate sprinklers and rainguns just as efficiently as trickle. In practice it is best to choose the system that is most appropriate to your farming system and crop needs. Case study Farmers assess their irrigation efficiency Over 100 farmers in East Anglia took part in the 5-minute Irrigation Performance Assessment whilst attending irrigation training workshops. The questions were carefully chosen to help farmers think more about their irrigation systems and to help them identify opportunities for improving operation and management. 50 Score 40 Minor opportunities 30 Moderate opportunities Major opportunities Farmers Initially only one farmer thought that he had major problems while two thirds felt there were only minor opportunities to improve their irrigation efficiency. On completing the training some felt that this result was more a reflection of their lack of appreciation of what irrigation efficiency meant rather than fact. Save water and money irrigate efficiently 07

8 Doing your own irrigation water audit A water audit may soon be required by some farmers irrigating in catchments where the aquatic environment and water resources are considered to be under threat due to an unsustainable abstraction regime. An irrigation water audit can pay real dividends not only by helping you to demonstrate responsible and efficient water management at licence renewal, but also in terms of improved farm management and profitability. It can help you to: Recognise the real costs and benefits of irrigation ( per m 3 of water) and the value of water to your business. This is invaluable when you are planning to further invest in irrigation, or considering a change in technology, or improving your irrigation efficiency. Identify any operational and management issues that can improve your water productivity. Better understand the important links between climate variability, irrigation abstractions, crop water use and equipment performance. Collecting and using information The Environment Agency has yet to define the kind of water audit needed for licence renewal. But it makes good sense not to wait and to start collecting basic information now on how well your irrigation system is working and on your soil and water management practices. Just how much information you collect will depend on your local circumstances and the extent of your system. For a small farm, information relating to the farm as a whole should be sufficient. For larger agribusinesses information from individual fields may be more useful. In areas where farms are close to protected habitats (e.g. SSSIs) then information relevant to the sustainability of such sites will be essential. Information to collect: Background Historical irrigation abstractions on a weekly or monthly basis Crop type, irrigated area (ha), and total depth of irrigation water applied (mm) for each field in each year Other agronomic factors that influence irrigation practices e.g. misting, cooling, transplanting, irrigation to assist in crop lifting, and seedbed preparation Irrigation training for farm managers and operators. Irrigation network and equipment Pressure at the pump, head of each field, and at the raingun or sprinkler (weekly) Metered irrigation water use volume pumped and the volume supplied to each field (each irrigation) Infield water distribution uniformity (annually). Soil and water management Soil type and soil conditions in the field (annually) Crop being grown, planting date, crop cover, harvesting date (seasonally) Weather data (daily rainfall and ET) preferably close to the field (daily). Use the information to: Compare scheduled and metered water use Estimate costs, benefits and value of irrigation ( per m 3 of water) Correlate irrigation water use against climate. 08 Save water and money irrigate efficiently

9 An irrigation water audit is a short-term, operational activity, designed to monitor existing patterns of water allocation and use. It is intended to show that water is being put to good use, is not being wasted, and any measures being taken to improve irrigation efficiency. How often do you need an audit? The Environment Agency has moved towards a risk-based approach in much of its decision-making. So it is likely that the frequency of audits needed to support abstraction licence renewal will reflect the environmental consequences of inefficiency based on water availability in the catchment and the size of an abstraction. In high risk areas audits may be required on an annual basis whereas in low risk areas an audit every 2-3 years may suffice. This has yet to be decided by the Agency. Financially, there can be benefits from continuous monitoring of irrigation systems and practices in much the same way as farmers and growers monitor their crops throughout the growing season. 3 Small Abstraction (m per day) Large Likely frequency of water audit Once every 10 years Every year Low Risk to catchment water resource availability High How well are you irrigating? Farmers in Australia use benchmarking to make objective comparisons between their own irrigation performance and that of best practice elsewhere. Confidential web-based systems enable farmers to input their irrigation data and to see how they compare with others who are irrigating under similar circumstances. Key performance indicators used include irrigation abstraction and application, crop production, business processes, and environmental impact. In the future, benchmarking might provide UK farmers with a means of comparing, in confidence, how well they are performing relative to other growers and help to answer key questions such as Where am I now?, Where do I want to be?, and How do I get there? Gross return per megalitre ($ per Ml) Low value variety Premium variety 1 Premium variety 2 Farms Source: Save water and money irrigate efficiently 09

10 Further information Contacts Copies of this publication are available from Cranfield University and the UK Irrigation Association. Please contact: Jerry Knox Centre for Water Science Cranfield University Bedfordshire MK43 0AL T: ext 2756 E: W: Melvyn Kay UK Irrigation Association c /o The Old Vicarage Main Street, Torksey Lincoln LN1 2EE T: E: m.kay@ukia.org W: This publication is also available for downloading in pdf format from the UK Irrigation Association website. 10 Save water and money irrigate efficiently

11 Centre for Water Science Cranfield University Cranfield Bedfordshire MK43 0AL T: Environment Agency Kingfisher House Goldhay Way, Orton Goldhay Peterborough PE2 5ZR T: National Farmers Union Agriculture House Willie Snaith Road Newmarket Cambs CB8 7SN T: East of England Development Agency The Business Centre Station Road, Histon Cambs CB4 9LQ T: UK Irrigation Association The Old Vicarage Main Street Torksey Lincoln LN1 2EE T: Natural England Eastbrook Shaftesbury Road Cambs CB2 2DR T: This publication is produced as part of a Natural England Regional Farm Advice Programme to help farmers and agribusinesses in Eastern England make practical and cost-effective improvements to their irrigation and water resource management practices. It is based on material developed for a series of irrigation efficiency workshops organised by Cranfield University in association with the National Farmers Union and RTCS Ltd, and supported by the East of England Development Agency, the Environment Agency, and the UK Irrigation Association. The workshops, which were organised between 2005 and 2007, were initially funded by Defra RDS and latterly by Natural England. The authors of this publication Jerry Knox (Cranfield University) and Melvyn Kay (RTCS Ltd) wish to make it clear that the views expressed and content of this publication are those of the authors and do not necessarily represent the views or policies of the organisations listed above. Designed & produced by Visualidentity.co.uk Printed by Taylor Bloxham Leicester who have achieved the environmental standard ISO Printed on 9 Lives 80 Silk, Totally Chlorine-free, 80% recycled, 60% post consumer waste.