Focus on innovations in irrigation
Case study – Irrigated field vegetables/potatoes
Name / Anthony Hopkins – Wroot Water Ltd /Region / Yorkshire
Grows / Field vegetables and potatoes
Farm size / 10 ha
Anthony Hopkins runs an agricultural irrigation consultancy service but he also grows field vegetables and potatoes on 8 haat Thatch Carr Farm in Wrooton the border between North Lincolnshire and South Yorkshire.He uses a direct summer abstraction licence to take water from the River Torn for spray irrigation. But he also uses trickle irrigation for which a licence is not needed under current legislation. However this will change over the next few years.
Because of the high costs of delivering water to his crops and concerns about over-abstraction on the River Torn,Anthony is taking steps to ensure that he uses water as efficiently as possible. For this reason he has opted to use small rotary impact sprinklers – once the mainstay of irrigation in the UK some 50 years ago. Although some see this as ‘old’ technology, it has been given a new lease of life because of the changing circumstances and advances in technology. The pipes and sprinklers are no longer moved around the field on a daily basis. Rather the system is solid-set with all the pipes and sprinklers laid out at the time of crop planting which means that labour for irrigation is no longer needed during the growing season. The system is fully automated which means that lateral valves can be turned on and off simply by sending radio signals from the office to the lateral valve clusters in the field. Two particularly important features of this system are the high level of water application uniformity that can be achieved and the ability to apply water little and often. His normal irrigation regime is to apply 5-6 mm of water every 3-4 days. This is particularly advantageous for scab control on potatoes and for producing a uniform quality crop for marketing purposes. Anthony also uses the system to apply fertilizer by injecting it into the irrigation water. At 3 bar operating pressure his energy requirements are kept low.
All-in-all this is an old technology brought up to date that can compete with the latest trickle irrigation systems for precise application of both water and nutrients.
Anthony also uses trickle irrigation based on his own design following a study he made of irrigation techniques supported by the Nuffield Foundation in 1999. As well as manufacturing and supplying his trickle tape to farmers, he also uses the system to grow potatoes on the black peaty soils at Thatch Carr Farm. He uses 1.83 metre (72 inch) wide bed cultivation with two rows of potatoes per bed and a trickle tape along each row applying approximately 1.5-2 mm per hour. This ensures a good lateral spread of water from the emitters and avoids runoff. The system enables him to apply water precisely but it can also reduce nutrient leaching and risk from blight because the foliage is not wetted during irrigation. It can also make it easier to lift the crop at harvest. Anthony uses disposable trickle tape but he justifies the cost of this system, which is not the cheapest, by the additional income he gets through improved crop quality. Though this year’s harvest (2009) was excellent with no skin problems, the market price was low due to excess potatoes grown in 2008 coming onto the market from storage.
Anthony’s main concern is water availability in the River Torn which is already over-abstracted. At present he does not need a licence to abstract water for trickle irrigation but he suspects that getting a licence when trickle irrigation eventually becomes part of the Environment Agency’s licencing regime may prove difficult. To strengthen his case Anthony collects data so that he can demonstrate ‘reasonable need’ and ‘efficiency of water use’, two important conditions for securing an irrigation abstraction licence.
Precision water application equipment is only as good as the farmer’s ability to manage it well. This means accurately determining when to irrigate and how much water to apply. Anthony collects meteorological data via the internet from a weather station located on the farm. From this he calculates crop water requirements – how much to apply. He then monitors soil moisture to determine irrigation timing – when to apply the water. He also regularly walks the crop with a spade to examine the soil profile to make sure that his instruments are providing the right information – a simple but vital part of successful irrigation scheduling practice.
Anthonyalso benefits from sharing knowledge with other farmers and researchers. He is currently working with Becker Underwood and Branston Potatoes to study nematodes applied with the irrigation water for slug control. He is also involved in irrigation trials with Cranfield University to examine ways of monitoring soil moisture and scheduling irrigation only to those areas of a field that require irrigation.
Focus on innovations in irrigation
Case study – Protected soft fruit
Name / Steve Fauchon – Littlebrook Nursery01489 574072 /
Region / Hampshire
Grows / Soft fruit (strawberries)
Farm size / 2 ha
Littlebrooks Nursery, owned by Richard and Vernon Emery, and managed by Steve Fouchon is a specialist soft fruit grower located in Hampshire in the heart of one of England’s main strawberry growing areas. They produce over 1,000 tons of Class 1 strawberries annually between September and November and February and June in heated glasshouses and poly-tunnels on several sites covering some 2ha.
Littlebrooks know that irrigation is an essential part of achieving good high quality strawberry yields. But water resources in this region are under severe pressure with water demand expected to grow by a further 20 % by 2020. Some growers, like Littlebrook Nursery, use domestic mains water when abstraction licences are no longer available although the cost of mains water is considerably higher than direct abstraction. Whatever the water source, growers are under pressure to demonstrate they are using water wisely and efficiently.
Littlebrooks use traditional grow bag technologies on most of their sites but some five years ago they invested in a new strawberry growing system called ‘Pot-in-Pipe’ – a system well established in Dutch glasshouses but not widely used in the UK. This was one of the first systems to be installed in the UK. It comprises 250 mm diameter PVC pipes, supported at chest height for easy fruit picking, which carries 1.5 litre compost-filled plant pots, up to six per metre, located in holes cut into the top of the pipe. Littlebrooks use the system to grow 27,000 plants, two per pot, on a 0.5ha site. Each pot is watered directly from an overhead trickle irrigation system. As the system is designed for Dutch glasshouses some modifications were needed to accommodate UK structures but overall the installation cost was about £50,000 which is equivalent to £1.30 per metre.
Irrigation is controlled automatically based on set points from light monitors. Although the amount of water used varies depending on the climatic conditions in the glasshouse, on average the system applies the equivalent of 0.15 litres per plant per day. Nutrients are applied with the irrigation water. Water pH and electrical conductivity (EC) are all automatically adjusted. Compost samples are sent away for analysis every two weeks to ensure that the crop is receiving the correct balance of nutrients.
Manager Steve Fauchon says it is not enough just to match the water supply with crop water demand. He aims to ‘over-irrigate’ and produce 15-20 % runoff (30 % on a hot summer day). This, he says, is essential for healthy crop growth as it leaches any harmful salts through the compost. A benefit of the Pot-in-Pipe system is that the pipe holding the pots serves as a drainage channel and so excess water drains to a collection point for disposal or reuse. This is in contrast to many other growing systems where there is no provision for drainage leachate which spills onto the ground where it can cause weed growth and seep into and pollute local water courses and shallow groundwater. Steve sprays his drainage water onto a grassed area which acts as a buffer between the drainage water and nearby water course. A local nature reserve just downstream regularly monitors water quality and so far there are no signs of deterioration in water quality as a result of this approach to drainage disposal.
Steve regularly monitors runoff at key points in each glasshouse as this helps him to identify problems such as leakage and over-watering – the compost mix he uses is prone to water-logging and this can directly impact on yield.
Steve says the Pot-in-Pipe system is not the cheapest on the market but it does provide excellent value for growers as it is possible to grow up to four strawberry crops a year, although his system is currently only geared to producing two crops a year. It also offers excellent control over water use and drainage disposal, which helps to minimise any environmental impact.
Focus on innovations in irrigation
Case study – Irrigated field vegetables
Name / Alex Duncan – Langmead Farms /Region / West Sussex
Grows / Salad crops and vegetables
Farm size / 3,000 ha
Langmead Farms is located in the Chichester area and grows some 1,500 ha of vegetables and salad crops – baby leaf salad, lettuces, celery, spring onions, and organic vegetables – on high grade clays, silts, and sand. They also grow baby leaf in Spain and contract with Spanish and Dutch growers to produce out of season vegetables for the UK market.
Irrigation is key to their business. It is the only way that they can meet the exacting high standards for crop quality and timeliness required by their supermarket customers. Langmeads currently abstract about 1.3 million cubic metres (286 million gallons) annually from a mix of sources – rivers, rifes (man-made drainage ditches), and groundwater under licence from the Environment Agency. But water is in short supply in the south east and Langmeads are most concerned about coping in a dry summer when crop production and hence water demand is at its most intense. For this reason, they store up to 840,000 cubic metres (185 million gallons) of winter water in 16 reservoirs strategically located across their farm sites to augment their summer abstraction licences. An extensive pipe network links the individual farms so water can be moved to where it is most needed.
Langmeads do not like to waste water and so on one farm, which is remote from the rest, they store and recycle wash line water from a sister company – Nature’s Way Foods. The company uses mains water and water harvested from farm buildings to wash and process vegetables. This water is filtered, treated with ultra-violet light, and aerated to reduce BOD before storing it in a lined reservoir. This reservoir provides buffer storage so that irrigation demand in the field can be balanced with the effluent discharges from the factory. A recent butyl lined 45,500 cubic metre reservoir cost approximately £450,000.
The constraints on water availability together with the high costs of pumping and storing water mean that it can cost as much as £0.80 per cubic metre. So Langmeads take every opportunity to make sure that every drop counts. Traditional raingun irrigation machines cannot meet the tight irrigation specification for crop quality and so they rely on 55 computer controlled boom irrigation machines to achieve the required high levels of application uniformity. Each machine is capable of applying 25 mm of water to a strip of land 450m long and 54m wide over a period of 14 hours – similar in capacity to a traditional raingun. Low pressure (3 bar) sprinklers, located along the boom, reduce wind drift and reduce energy consumption. The typical costs for a hosereel fitted with a boom are about £28,500.
Langmeads Chichester Farm Manager, Alex Duncan, plants 60 ha of celery with disposable trickle tape. He believes that trickle irrigation will play an increasing role for vegetable production in the future. When properly managed the system offers potential for reducing water wastage and maximising crop productivity to water – more ‘crop per drop.’ Trickle irrigation can be automated and is designed to apply water little and often – sometimes on a daily basis. The system operates at low pressure (0.5 bar). It significantly reduces labour input and fertilizer is injected into the irrigation water so that it reaches the plant roots directly. Trickle tape is buried just below the soil surface at the same time as the pre-germinated celery is planted. The crop is grown in beds with one trickle tape watering two rows of celery. At harvest the tape is then taken up and re-cycled.
At present an abstraction licence is not needed for trickle irrigation. But this is set to change in the next few years as the Water Act 2003 is implemented. So Alex makes sure the water he abstracts for trickle is fully monitored so that he has evidence on which to base his claim for a licence to continue abstracting in the future.
Making sure the right equipment is used on the farm is one thing. Managing the systems is another – deciding when to irrigate and how much water to apply to each crop. Scheduling irrigation on a day to day basis is a balance between how much water the crops need and the availability of irrigation equipment and pumps to apply it when it is needed. To achieve this balance, Alex, his fellow managers, and irrigation contractors walk the crops three times a week in order to plan how the irrigation equipment will be allocated across the various sites. He also relies on weather stations located on each farm to automatically provide data for calculating crop water requirements using a soil-water balance model. This is supported by regular soil moisture measurements using tensiometers and capacitance probes which both inform and confirm the crop water requirement calculations.
It is good irrigation practice to use more than one method of scheduling. Walking the crops, gathering meteorological data, and checking soil moisture means that Langmeads can have confidence in their irrigation systems and management practices – a ‘belt and braces approach’. After all, there is too much at stake to get this wrong!
Focus on innovations in irrigation
Case study – Hardy nursery stock
Name / Jan Lansen – Lansen Nursery /Region / Spalding, Lincolnshire
Grows / Salad crops and vegetables
Farm size / 6ha of open site and 0.5ha under glass
Lansen Nurseries produces some 2 million pot grown plants annually – bedding plants, perennials, and hardy ornamentals – for landscaping and for the supermarkets on their 6 ha site, 0.5ha of which is under glass, in Spalding, Lincolnshire. Irrigation is essential for pot plants and in the past the nursery relied on domestic mains water costing over £80,000 a year. So in 2000, Jan Lansen decided to look again at this important aspect of his business to see if there were alternatives to mains water, sprinklers and hand-watering application methods. He came to the conclusion that the best method for his business was the innovative Dutch ‘ebb and flow’ irrigation system which eventually reduced his annual water bill to about £2,000.
The ‘ebb and flow’ system is known in Holland for its simplicity, reliability, and low initial investment costs. Pot plants are grown in large level basins lined with an impermeable membrane. When it rains the basins collect the rainfall and any excess water is pumped from the basins and stored in tanks – the ebb. When the plants need watering the flow is released from the storage tanks back into the basins – the flow.
Over the past decade Lansen have gradually constructed 107 lined beds across their 6 ha site both outside and under glass – each 250 or 350 m2 in size. The beds were created by turning up the subsoil, mixing it with top soil, and compacting it to a hard surface. This was then covered with an impermeable membrane to stop seepage. Basins were precision graded to provide a 2% slope towards an inlet/outlet pipe located at the centre so that each basin could be quickly and completely drained with no low-lying spots where water could collect and waterlog the pots.
Rainwater is pumped from the basins via the central outlet into water storage tanks. The pot plants are irrigated by reversing the flow from the storage tanks into the basins. Gutters or small channels across each basin encourage fast flow towards the centre during drainage and rapid flooding during irrigation. Once the basins are flooded, capillary action ensures the pots are well watered. Plants are grown in relatively free draining compost with 20-25% bark. Fertiliser is added to the irrigation water and so plant types requiring similar water and fertiliser regimes are grouped together in basins in order to simplify irrigation management practices. Typically, basins are flooded to a depth of about 60 mm for 6 minutes and then drained. Over-irrigation is not a problem as any excess irrigation water is drained and returned to the storage tanks. Irrigation water EC is automatically checked four times before water is released for irrigation and valves are regularly cleaned to ensure accurate measurement. Fine screens are used to make sure water is clean and free of the smallest weed seeds. Recycling chemical fertilisers and regular water quality monitoring help to reduce the risk of polluting the local water environment.