Making the most of every drop
The trick to efficient irrigation scheduling for potatoes is to apply water in small doses, frequently and uniformly, according to NIAB CUF senior research associate Dr Mark Stalham.
Difficulties in getting round the fields with irrigation equipment have led to some growers waiting until the soil moisture deficit is high, before applying more water. However, the higher the dose of water applied, the more likely it is to be wasted, with up to 15 per cent of water applied being lost into the furrow, he explains.
Larger amounts of water can also filter too quickly through dry soil, particularly if they are sandy, putting the crop under more stress.
Dr Stalham says: “If you use a soil moisture probe at a depth of 50cm and it shows a spike of water a few hours after irrigating, the water has probably gone beyond the depth of roots and has been lost.”
He recommends at least three probes per field as they only give a snapshot of what is happening in the field in one place at a given time.
“There are variations in soil properties, plant growth and irrigation distribution, and as sensors record very small volumes of soil, they are effectively measuring what is happening between two plants when there might be 300,000 in the field.
“Moreover, there is no single ideal location in the ridge, and the ‘standard’ row centre position is always drier than the average, which can lead to over-irrigation.”
Ridge shape can also affect run-off into the furrow so getting them as broad and flat as possible should be the target.
Uniform applications should be a priority, he emphasises. Trials looking at water in the soil profile have shown that even when the bed system is dry enough to accept 15mm of water without loss, the centre of the bed can be as dry as before irrigation.
When summers are as warm as 2018, many growers are concerned about high water loss through evaporation, leading many of them to stop irrigating during the day. Work done in southern France using 2–4mm diameter nozzle sprinklers showed losses of 15 per cent during the day at 35ºC and only 0.6 per cent at night.
Even during really hot spells, the loss is much lower than most people’s estimates, says Dr Stalham, since most people don’t use sprinklers.
“The highest evaporation rate ever calculated for a rain-gun with 24mm nozzle at 5 bar at 2pm on the hottest day in 1990 was 4 per cent, or 1mm loss per 25mm application.
“Wind can be more of a problem when you use rain-guns, because it makes it difficult to achieve a uniform target application across 72m wide bouts.”
Moving on to discuss the benefits and pitfalls of using drip irrigation, he says: “Drip irrigation can be highly effective at soil wetting, and of course there should be less evaporation and water is not blown off course by the wind, however, it needs to be correctly set up with attention to detail in pipe and emitter spacing.
“You need to match emitter spacing according to planting density, tape or pipe spacing and flow rate, taking soil profile and texture into account or you will find localised wetting leaving some of the plants as dry as before irrigation.
“It is also crucial to monitor your soil moisture carefully with probes or a spade as it can be easy to over-irrigate.”
Research starting in 1992 on irrigation regimes showed differences in both total yields and the proportion of surface area affected by common scab (streptomyces scabiei) and highlighted differences between the various methods of irrigation.
“The best drip irrigation schemes can improve yields, but you will not save water,” emphasises Dr Stalham.
He also reminds growers they should adjust early season irrigation scheduling strategies according to varietal susceptibility to common scab.
“If the variety you are growing is in the red group (see Table 1) you need the belt and braces approach. However, if it is in the green, you may be able to save between one and two irrigation events as populations are smaller, so irrigation frequency can be less.”
Land drainage project
Arable farmer and potato grower John Davies was looking to drain land that had previously been installed with old tile drains during the 1970s.
These had worked well for years, but had recently started to fail and the need for good drainage, especially when growing potatoes is essential. Fen Group carried out an initial survey of the land and presented John with maps of the fields and recommendations for the most efficient drainage. The company then brought in its new Masterbroek 20/15 trencher to implement the plan using 20m laterals and 80mm pipes back-filled with stone.
Fen Group is now carrying out land drainage work on farms across East Anglia and the Midlands. Alongside its sister company it is equipped to deliver the full package from ditch maintenance to full drainage systems installed using the latest satellite mapping.
Irrigation challenges ahead
Many farmers who are dependent on irrigation for key crops face a challenging summer, according to the latest predictions on water availability.
Large parts of eastern England saw a fraction of the usual rainfall over winter and spring. For example, in East Anglia the cumulative rainfall total for April was just 19 per cent of the monthly long-term average. Growers have struggled to fill reservoirs and aquifers are depleted.
Other parts of the UK including the South East initially fared better, and earlier in the year prospects for this region were assessed as ‘good’ in the Environment Agency’s forecast. However even here they had been reduced to ‘moderate’ by mid May.
Advice to farmers from the NFU and UKIA (United Kingdom Irrigation Association) has been to monitor prospects carefully and plan ahead where possible. The Environment Agency has also launched a water rights trading map for East Anglia, Midlands, Northants and Lincs regions. This map pinpoints licence holders and relevant details in each area.
After last year’s dry season farmers are well aware of the challenges and are ensuring they have the most effective equipment for their irrigation needs, according to Briggs Irrigation managing director, Adrian Colwill.
“In the UK sales of our irrigation booms are at the highest level we have ever known, he says. “As much of Europe was affected last year, exports are also strong. Farmers clearly understand that a modern boom is efficient and accurate, giving them the flexibility to target crops as required. Water is already a valuable and scarce resource this year and growers are getting prepared.”
A tool to improve soil structure
Mole draining is an important tool to help rectify poor drainage and improve soil structure, by taking excess water away to the drainage system.
While poor drainage and compaction are less evident after a dry season, heavy clay soils need checking for root formation.
Rotational moling is recommended at a time when the soil is moist enough to form a ball but the shallow subsoil is dry enough to shatter, and to a depth of 500-600mm.
With costly inputs it is important to maximise crop yields as it costs as much to produce a good crop as a poor one if drainage is not in order, warns Hankins Engineering. Mole draining will significantly enhance crop production and the cost of moling will be retrieved many times over through efficient drainage, it says.
The Maidwell Molers are manufactured by Hankins which has more than 35 years’ experience in mole drainer production. Maidwell Molers have a beam construction with high ground clearance and a unique screw-adjusting double-ended leg, incorporating a shear bolt device, acting as a safety release mechanism. The robust single-, twin- and three-legged machines, mounted or trailed, are built to a very high standard to cope with work behind high horsepower tractors and crawlers.
Power on the Land
Irrigation equipment was working as early as April in some areas this year following several months with below average rainfall. Mike Williams provides an update on the latest irrigation equipment available.
Dry conditions in the East of the country during April, following low rainfall last summer, has emphasised the value of irrigation and the fact that for many farms water can become a scarce resource. Equipment suppliers are reporting a high level of interest from farmers wanting to update or extend existing systems, and developments that can increase application efficiency are often high on the priority list.
The slogan for irrigation equipment made by Yorkshire based Jones Engineering is “irrigate smarter, not harder”, and the options for its pump units and hosereels include remote control of stop and start by using a mobile phone to provide increased accuracy and flexibility. Among the advantages the company claims for its boom irrigation systems is greater control over the droplet size, allowing a balance to be chosen between larger drops that help reduce losses due to drift and evaporation, or smaller drops with reduced soil surface impact.
Jones pump units use a JCB engine to power a Caprari pump, with an acoustic canopy to reduce noise nuisance, and the security features include a removable drawbar and the 1,000- or 1,500-litre capacity diesel tank is designed to prevent fuel syphoning. The linkage mounted Lay Flat Recoiler is a recent addition to the Jones range and it has a fully galvanised drum holding up to 1,000m of 100 or 125mm lay flat pipe and is equipped with lights for road travel.
Irrigation and slurry
The Bauer machinery range from Austria offers one of the biggest selections of irrigation equipment plus slurry and dirty water handling systems. The equipment is available through a selected network of UK dealers offering both new and reconditioned used machines. They include the Rainstar range of hosereel applicators available in both two- and four-wheel chassis versions, plus irrigation boom systems. Special features available for the Bauer applicators include electronic monitoring and control equipment to maintain accuracy, with remotely transmitted data allowing constant supervision and adjustment.
As well as the machinery range, Bauer offers a comprehensive choice of ancillary items including pipes, hoses, valves and couplings, and to maintain peak performance there is also a range of repair parts and kits including gearbox spares and irrigation boom components.
Hosereel applicators with a telephone link for remote monitoring and control are also available in the Ocmis range from Briggs Irrigation. The hose reels are available on two or four wheels with pipe lengths ranging from 160–700m depending on the model and pipe diameter, and flow rates range from 15–24 m3/hr for a small capacity model to between 40–120 m3/hr for the company’s largest hosereels. SMS messaging is available to provide constant remote access for monitoring and control.
Mobile irrigation pump units that may be left for long periods working in remote parts of the farm are an obvious security risk and the Briggs range features anti-theft precautions. These include a removable drawbar, the fuel tank contents are protected by a filler cap with a high security padlock, all the opening panels on the acoustic canopy have locking handles and the colour options for the canopy panels include a shade of green that makes the pump less conspicuous.
Briggs mobile pumps are powered by JCB engines with outputs from 74–173hp and the bunded fuel tank holds 1,500 litres.
While irrigation can compensate for a lack of water, drainage is an essential requirement where there is too much water, and Miles Drainage offers a comprehensive range of services for land drainage. The Suffolk based company has a long history, established more than a century ago to provide steam ploughing and cultivation for local farms, but it now offers a country-wide service specialising in drainage and associated activities such as ditch maintenance, mole draining and drain jetting.
Trenchless draining is available where minimum ground disturbance is required, but most of the company’s agricultural drainage work is handled by Mastenbroek trenchers which are now equipped with the latest GPS based guidance equipment. One of the benefits of using GPS instead of the previous laser system is that GPS is not affected by weather conditions, avoiding delays that occurred when poor visibility restricted the performance of the laser. The mole ploughs used by Miles are made in its own workshops, based on many years and thousands of acres of experience, and it also makes the mole ploughs for sale.
Agricultural drainage work is high on the list of activities for the Essex based Hugh Pearl company, but its expertise is also available for draining sports and amenity areas and for drainage work linked to highways and other civil engineering projects. The business was established more than 60 years ago and it is now active throughout the eastern counties from the East Midlands to the south-east, and in addition to drainage work it also offers a number of specialised services such as gas extraction from sites used for landfill plus geothermal heat reclamation systems.
As well as planning and installing field drainage, Hugh Pearl is also available for ditch maintenance and improvement work, and another of the company’s services is reservoir construction and this includes constructing new reservoirs as well as increasing existing capacity for storing water for irrigation.
Hugh Pearl also excavates lakes and other water features for amenity and recreation areas including fishing. It provides storage capacity on livestock farms to contain slurry and dirty water, and another activity is installing or extending water supply systems on farms.
Mobile device app for irrigator management
Remote management of Bauer Rainstar irrigation reels, the Centerstar centre-pivot system and the company’s range of diesel irrigation pumps – including the new ‘silenced’ versions introduced for this year’s growing season – is all possible with Bauer SmartRain.
The online irrigation management system, which comes with a mobile device app, provides immediate access to information on the progress of irrigation sessions so that reel moves can be anticipated and organised in a timely manner.
It also issues alerts on any problems that arise so they can be sorted out promptly to minimise downtime and disruption to irrigation schedules.
“Remote monitoring of our Rainstar irrigators and diesel pumps can save growers and managers a lot of time and brings greater efficiency to the management of these systems,” says Bauer UK & Ireland sales manager, Adrian Tindall.
“It also enables them to focus on other tasks safe in the knowledge that their irrigation systems are being monitored at all times while also recording valuable information through the documentation feature.”
This element of SmartRain automatically saves water use records and details of individual irrigation system operation based on measurements and information about soil conditions, soil moisture, and the size and shape of different fields.
Online data can be accessed via an office computer or the mobile device app to optimise water-use management and minimise operating costs.
SmartRain requires a solar-powered GPS controller, mounted on the chassis of a Rainstar reel irrigator or the Universal PRO-G control unit on the central tower of a centre-pivot system.
Drainage product supplier with roots in farming
JKH Drainage Units Ltd offers specialist pre-cast concrete products for a wide range of industries but its roots are in agriculture.
The company was founded in 1969 by John Kenneth Hoare and is currently run by John’s son-in-law Brian Prince and two of his sons have also joined the firm.
A major motivation for setting up the company was to assist with John’s other business which was in agricultural drainage. The company’s primary purpose was to manufacture concrete headwalls and chambers that were easier to use and therefore much quicker to install. This helped to reduce costs for customers. The benefit that this provided to other contractors allowed sales to increase and allowed the company to expand across the UK.
The drainage contracting business was promoted by the government during the Second World War as part of a concerted effort to encourage farmers to increase their home-grown output. Agricultural drainage grants were seen by the then Ministry of Agriculture, Fisheries and Food as a way to improve the land and increase the quality and quantity of the crops grown. John started the company not only to make a living but also to help farmers to increase their yields in the counties of Essex and Hertfordshire.
In 2019 JKH provides a package that includes the concrete product complete with the necessary steelwork or control mechanisms, which means it is able to solve a large number of problems off-site. As well as tailored solutions, the company also offers stock products.
Irrigation pumping solutions
Italian manufacturer Euromacchine offers irrigation pumping solutions from diesel engine irrigation motor pumps to the multifunctional Lampo unit that can be simultaneously used as a generator and a pump unit with the ability to vary flow rates and pressure through an inverter.
New to the UK is the SR range diesel engine motor pumps. These use a heat exchanger inside the Supertank priming system, allowing the engine to be cooled without a radiator. There are many benefits to this system including less fuel consumption and reduced noise, says Euromacchine. Other features include a bunded fuel tank, automatic priming plus the ability to control and monitor the pump unit remotely from a mobile phone.
Supertank allows self-priming of the single and the multistage Caprari and Rovatti centrifugal pumps. The Supertank system ensures the filling of the suction side simply and quickly, says the manufacturer. The Supertank kit is available in manual or automatic versions on new pumps or to fit existing pumps.
Riverscreen is a rotating water-driven, self-cleaning screen that reliably filters and delivers water from as little as 4in depth. It can be used when abstracting from a reservoir, river or canal where weed is a constant problem. Importantly it gives protection to fish and eels. Capacities range from 20–600m3/hr.
Launch of new irrigator models
The Elite irrigator range from Irrimec is being extended this season with the launch of the 800 series machines.
These have been designed with the professional grower in mind, says Greencrop. They start at 110mm x 600m up to 120mm x 700m.
Each machine is steel shot blasted, painted in epoxy anti-corrosive primer, with a final coat of oven baked polyurethane paint for a long-lasting finish, it says. Trolleys are hot galvanised and the lifting frame is operated by hydraulic rams for lifting and lowering the trolley.
The drum is driven from both sides with a cut gear ring positioned on the outer diameter of the drum. Unlike a chain drive, the hose drum is driven by a low-torque gear drive, which is positive and low wearing.
The new Dosicontrol Pro computer has built in GSM with the ability to record hours worked and water used among other diagnostics.
The chassis is constructed of large steel frames using 5mm thick box section. The 800 series are built around a tandem axle design with large flotation wheels. Hydraulic legs are 50 per cent larger with built-in internal rams for improved weather resistance and are designed to exert a central push against the drum for added stability. It is supplied with a full hydraulic system with the control levers now mounted on an adjustable stand at the front of the machine.
The hose guide has not one but four metal bearing rollers guiding the hose onto the drum. Self-pivoting gun trolleys have been made 50 per cent stronger.
Longer hose versions will be available later, says Greencrop.