Effective irrigation is key to achieving top yields
Crumbly, friable soils with a loose surface texture are essential if plants are to gain full benefit from irrigation, however timely irrigation with the right volume of water applied in the best way is equally important if yields and quality are to the maximised, according to specialists.
During seminars at Briggs Irrigation’s December open days in Corby, Northants, Soil Moisture Sense’s Peter White asked farmers whether irrigating all their crops badly, or doing some very well and some not at all – would make them most profit?
Mr White suggested that many growers would increase profitability by irrigating fewer crops, but doing them better.
“In 2018, yields of many crops varied significantly, depending on local rainfall and irrigation. Onion yields, for example, fell by 40 per cent on average but the range was huge, with between 7–100t/ha recorded. Effective irrigation had a major part to play in achieving yields at the upper end of the scale,” he pointed out.
As yield is proportional to water use, for many growers this meant applying 30mm of water twice a week. But if plants are to use this water effectively, application and infiltration rates must match. This means ensuring water can penetrate the soil and is available to the plant in its active root zone at a rate it can consume.
In practice, smooth surfaced ridges and beds, often seen on good quality silt soils, shed water which may then run off the land along compacted wheelings or down the furrow. Capped soils present a similar problem. Water logging following heavy applications of water, or when rain follows, also results in stress, causing a temporary slowdown in growth and subsequent reduction in yield and quality.
In a worst case scenario the ridge can be dry, again leading to drought stress, restricted growth and minimal scab control while the furrow is saturated, potentially leading to leaching of nutrients. As the canopy of plants such as potatoes grows it can disperse the droplets and reduce the problem but by then much of the benefit of irrigation can be lost.
One way of avoiding these problems is to ‘pre-water’ with a light application before the main irrigation pass, Mr White suggested. For example, in a very dry potato ridge the infiltration rate may be too slow to take a 30mm boom application in one go. Paired applications may therefore be more effective. Wetting agents could also be useful, he added.
In all situations, monitoring soil moisture is essential, he said. Modern probes can help record the impact of irrigation at different depths. With the aid of accurate data it is possible to balance application rates with infiltration speed. Cultivation techniques can also be compared, along with the impact of changes to irrigation techniques such as trying different nozzles or wetting agents.
Methods of getting water onto the soil without damaging crops or the soil itself, and without waste, were examined in greater detail by independent mechanisation specialist Bill Basford.
Booms are capable of applying larger volumes more quickly than rainguns, peaking at around 30mm/hr compared with 20mm/hr for rainguns, he pointed out. When both are operating at optimum pressure a boom also delivers much smaller droplets; 90 per cent of which are likely to be below 2mm in diameter compared with 90 per cent above this size for the raingun. As doubling the droplet size increases its weight eightfold, the impact on the soil and plant can be significant. Water from a raingun also has greater velocity, in part because it leaves the gun at around 75mph, he said.
Mr Basford also highlighted the importance of soil structure, pointing to the huge differences in the rate of water infiltration caused by soil compaction from multiple tractor passes. Slopes must also be taken into account, he suggested, with a slope of just 5 per cent probably reducing infiltration by 50 per cent.
Practical means of reducing run off are already available, he noted. These include the Briggs tied ridger which creates small dams between beds. These should be removed before harvest, perhaps with a front mounted tine. A spiked roller such as the Aqueel indents the surface of the bed, making it more receptive to water. There are also simple machines to break up the furrow, such as Bye Engineering’s Wonderwheel.
Back to basics
It is also important to remember basic principles of irrigation, stressed Mr Basford. “Optimum operation of all irrigation equipment depends on maintaining sufficient pressure throughout the system. Rainguns require the highest pressure and if this falls, droplet size increases, which may cause damage or capping, uniformity is lost as there are fewer fine drops to ‘fill in’, while on exposed sites it is harder to combat wind drift. Our trials have shown that areas of the crop will therefore receive insufficient water.”
Ensuring there is adequate pressure is dependent on good design for the whole system, he stated. For example, in a ‘typical’ system, increasing the diameter of the pipes from the ring main to the spurs in the field by 25per cent could save around 3.5bar in pressure loss, improving uniformity and optimising droplet size.
Energy losses through the turbine should also be taken into account.
“In modern hosereels the pressure loss is 0.4–0.8bar, depending on the speed at which the hose is being retracted, whereas for older designs the loss is 1.5–3.0bar. Updating equipment can therefore be cost effective.”
The pros and cons of using boom irrigators are well established, he suggested. Advantages include the ability to manage droplet size for different crops and various stages of growth. Crop and soil damage can be minimised and uniformity is excellent. Booms also require less energy than rainguns as they can usually operate at just 2–4bar.
Conversely booms may require a little more labour to set up, although they are still relatively easy to handle. They also cost more and growers need to be aware of the effect of placing high volumes of water on their land over a short period of time. However, based on a typical system being operated on 20ha over 5 years, including depreciation, repairs and labour, a boom irrigation system will have an approximate cost of £162/ha.
Automation may also be worth considering, purely on the basis of time saved, continued Mr Basford. For example, saving one hour a day, plus mileage can easily equal £18/day overall. If 120 days are spent irrigating, the saving is £2,160. A one-off cost of £1,330 for an interactive telephone control system is therefore quickly recouped.
The ability to monitor, control and record using systems such as Brigg’s Raindancer adds further benefits and enables improved management across the farm.
Solutions for flood and water management
As part of a four year contract Fen Group is maintaining more than 40km of counter drain which runs adjacent to the Old Bedford River.
The group has been tasked with carrying out a variety of operations for flood protection and habitat management including dredging, weed cutting and weed raking.
The material which is dredged from the counter drain is then left to dry until the following season, when it is levelled and integrated into the adjacent habitat by re-seeding. Due to the species rich body of water it is important to use bio oils in the machinery and due to Fen Group’s experience working for nature reserves it has several specialist pieces of machinery which run on bio-oil including a 15.5m reach 220 JCB excavator.
Maintaining water courses, from ditching to dredging, to embankment protection are just a few of the services offered by the Fen Group to help its customer achieve flood and water management.
Upgrades for drain-jetters
Various new upgrades to its range of drain-jetters have been revealed by Mitchell Rowlands.
The Professional has been improved with a new 700m capacity drum complete with heavy duty frame to accept the additional weight which has been developed over the past two years and is now offered with ease of attachment to the tractor.
Twin hydraulic anti-slip motors are standard on the drive system with four special 200mm wheels to grip the hose, which the company says is a must when you consider the power required to push and pull lengths up to 700m.
The second new feature is hydraulic braking on the drum motor to stop over-run when rewinding. The company now offers the guide arm on either left or right hand side of the Drainjetter to special order. It also has a hydraulic rotating guide arm end as an option too. “This makes it very easy to do the drain outfall either side of the ditch from one tractor position without getting into the ditch,” says the manufacturer. It also has a remote control function.
Meanwhile a new model – the MD 80 – has also been announced. This machine derived from the successful MD 50 is water powered with up to 300m of hose. It gives high pressure 80 bar jetting with 140-litres/min water at the head. The drum has hydraulic retrieval as standard; this can be operated with wireless remote control as can the water on and off function.
Septic tank legislation changes
By the 1st January 2020 all septic tanks that discharge into a watercourse or a ditch will need to be replaced with a sewage treatment system. It is estimated that 60 per cent of sites will fail the new legislation.
This is the final date by which systems must be upgaraded, and properties sold before this will have to comply.
If a septic tank system discharges into a watercourse, such as a stream, river or a ditch, the system must be changed to discharge into a drainage field.
If the course of discharge cannot be changed, the system must be replaced by a treatment plant. The treatment plant must have a full BS EN 12566-3 certification. If a property is deemed as environmentally sensitive there is extra protection in place to cover this. Where this is the case a permit will need to be applied for.
Owners of a septic tank or small sewage treatment plant, by law must comply with the general binding rules and ensure that the system is maintained properly and does not cause pollution.
John Davison Pipes can assist with the switch over and has a dedicated technical support team to answer any questions or concerns as the deadline approaches.
Pump sets for drip irrigation
A new range of budget irrigation pump sets has been launched by Greencrop.
The range includes economy diesel engines and irrigation pumps that will drive a single hose reel irrigator fitted with either a rain gun or boom. They enable increased use of drip or tape irrigation, where existing pump sets on the market are over capacity for these applications.
The two new models, the GCEP051W and GCEP075W, both have bunded tanks and control panels as standard. The GCEP051W unit is powered by a water cooled Perkins 404D22 (TIER 111) 51hp 4 cylinder with a Rovatti F43K80-90/3E pump, which is ideal for running drip or tape irrigation but still able to run one irrigator.
Standard specifications include 66m3/hr – 89m at 2,200 rpm, 66m3/hr – 69m at 2,000 rpm and 66m3/hr – 48m at 1,750 rpm.
Other features include flow switch, manual priming pump, delivery butterfly valve, a roof to protect the engine from rain and a special bunded chassis with internal capacity of 800 litres. There is also a lockable fuel cap.
Optional extras for both pump sets include suction and delivery fittings, electric primer, acoustic lockable engine cabinet and GSM control.
Optimal drainage for soil health
Subsurface land drainage can increase crop yields by as much as 35 per cent, although root ingress and sedimentation can greatly reduce the effectiveness and profitability of these systems. Maintaining a clear and unobstructed path for subsurface water to flow is crucial for soil health.
The Mastenbroek P-15 drain jetter can help maintain optimal drainage performance, says manufacturer Mastenbroek. Featuring a high-quality 85 bar pump fixed to a heavy-duty chassis which delivers 15-20 bar at the nozzle at 120-litres/min, the P-15 is fitted with a pressure pulsation system which enables penetration into most hard, compacted blockages. The PTO driven pump features three large diameter, long stroke cylinders which provide positive suction and tolerance to dirty water drawn from drainage ditches.
A 300m length of flexible hard-wearing sewer hose as well as a variety of torpedo nozzles facilitate highly efficient jetting in long, variously diametered pipes. Each nozzle features four reverse facing water jets which function to propel itself along the pipe unassisted.
The P-15 features a hydraulically assisted hose guide arm with pivot and telescopic extension to align the nozzle into drainage outlets on either side of the ditch. The hose drum rewind is also hydraulic, to assist recovery of the hose. The simple, reliable design of the P-15 allows for maximum ease of operation and maintenance.
Political and climatic factors fuel drainage demand
With uncertainty surrounding the future of the Basic Payment Scheme along with ongoing price volatility in the global market place, many farmers have been examining their cost base carefully.
One area which features high on the priority list for many is addressing a ‘back to basics’ approach to soil management. Soil health, black grass control and a general need to farm soils in the best way possible is an absolute necessity in 2019, says drainage contractor William Morfoot.
The installation of new land drains as a tool to improve soils and enhance yield prospects is an obvious starting place for many growers. The current political uncertainty has led to many growers looking to install new drainage schemes to provide the additional yield they strive for, says Morfoot.
“The combined effects of Brexit, rainfall extremities, declining effectiveness of existing outdated drainage systems coupled with an obvious requirement to promote soil health in order to maximise yields means that drainage investment has been an easy choice to make for many of our clients,” says the company’s James Frary. “As a result, investment in drainage has been considerable in recent years.” With yield monitoring now being used as a tool to record yield information each year, the return on investment in new drainage schemes is easier than ever to gauge.”
Many customers are so impressed by the yield increases and improvement in soil structure brought about by installing drains that they decide to invest further, he adds.
William Morfoot can provide a complete design and installation service and operates across the UK. It runs the latest in GPS guided trenching machinery and associated ancillary equipment.
Mole draining helps maximise crop yields
The extremely dry conditions of 2018 did not provide an ideal moling year so, if conditions are right in 2019, it will be a very important ‘catch up’ year, according to Hankins Engineering.
Mole draining is a fine art and, when done properly, it can bring long lasting benefits to soil health by allowing crop roots to grow more deeply to search for nutrients.
Well-drained soils can help maximise crop growth and yields and make the operation easier and cheaper, says the company.
This is because not only is less time needed to do a job when soil conditions are good, but also fuel costs can be lower.
Moreover, it points out, a badly drained field will be more susceptible to disease and weed problems, resulting in a below-average crop that has cost more to grow.
To achieve well drained land you need the correct tool for the job and the right conditions, emphasises Hankins Engineering.
Since the design of the first tractor mounted Maidwell Moler over 35 years ago, Ron Hankins of Hankins Engineering has gone on to develop a wide range of machines from single-leg mounted and trailed molers, to twin- and 3-leg machines.
Although there was very little moling done during 2018 Hankins Engineering was very busy draining and moling in water pipes with its single-leg Maidwell Moler.
Ron Hankins is always available to give advice and discuss requirements, adds Hankins Engineering.
Drainage investment yields gains
When last year’s extreme weather conditions highlighted drainage issues on farmer David Blacker’s Yorkshire farm he decided to invest in machinery to drain the areas of his heavy, clay-based land.
He invested in a Shelton CT150 chain trencher, a tractor mounted trencher, with the option of GPS or laser grading technology, plus ancillary machinery to carry out the work.
David said: “I did my research and chose the CT150 as I liked the fact it would dig a deep trench, up to 1.5m and used 3-point linkage.
“When working it sits on a large plate that gives better continuity across the field. Initially, we drained about 2 hectares of a 40 hectare field. We trenched directly into areas of drilled crop which had failed and installed mains and laterals.
We did the work during the dry spell, so the results weren’t immediate, but after the first rain, I couldn’t believe the amount of water which ran out of the exit drain, even during such a dry period. I have done 14 hectares for myself in the first year with some impressive results.” Neighbouring farmers were keen to get similar results so David started contracting work with it and is now earning an income from the machine.
Balance of soil, water and air crucial to crop yield and quality
When irrigating, ensure that crops have the correct amount of available water at each stage of growth, advises irrigation specialist Anthony Hopkins of Wroot Water.
A typical soil will consist of 50 per cent sand, silt and clay, 25 per cent air and 25 per cent water, and when a crop is growing and transpiring, it will draw water from the soil water reserve, which changes the balance of the soil, air and water, he explains. If there is too much water, the plant has insufficient access to air, and when the balance swings the other way and is too dry, it reaches the point where the plant will wilt (see diagram).
This is where a good irrigation system will replenish the balance to keep the crop growing without saturating the soil.
“It is important not to exceed the infiltration rate of the soil when irrigating. This can vary according to soil type, and, additionally, if there is slope infiltration will be reduced,” says Mr Hopkins.
“You must also ensure the water travels through the profile sufficiently to meet the crop needs.
“When the balance of soil, air and water are at their optimum proportions, despite different soils having different available water capacities, you will achieve healthy soil and healthy crops, in addition to reducing soil erosion and chemical and fertiliser leaching.”
Various services and irrigation systems to suit all crops are available from Wroot Water, and the company uses the latest soil moisture monitoring equipment together with the new ‘Wroot Water Canopee Total control’ that enhances the Wroot Water irrigation system.
Irrigation kit added to portfolio
Farm and professional horticultural equipment supplier Burdens Group has added Bauer irrigation products to its portfolio of machinery for specialist growers.
Burdens is now handling the Bauer irrigator range of hose reels, centre pivots, rain guns and sprinkler booms throughout Lincolnshire, east Nottinghamshire and north Cambridgeshire.
Bauer irrigators complement a comprehensive range of specialist equipment for salad, vegetable and other commercial horticulture crops supplied by Burdens Group.
“We are now in a position to supply some of the best irrigation equipment around; it’s heavy-duty, has a very efficient water turbine drive system, and as little or as much electronics technology as you want,” said Burdens’ specialist crop sales manager, Andy Wilson.
“Pretty much everything, including steel pipe and the famous Bauer coupling, and the polyethylene tubing that goes on the reel, is manufactured by Bauer in its Austrian factory for optimum quality control.”
The Bauer Rainstar irrigation reel line-up extends from the compact T Series, which starts with the T32 model handling Bauer PE pipe in 65-85mm diameters from 220-350m in length, through the full-size E Series, which tops out with the E55 XL carrying 125-140mm diameter pipe in 560-740m lengths.
High pulling force – up to 40 per cent greater than with some irrigation reels – is generated by an efficient radial water turbine, working in conjunction with a gearbox, a heavy-duty drive chain and large diameter laser cut reel drive sprocket.
The Bauer turbine’s design and precision assembly ensures it operates with very little water pressure loss, while the unique Vario variable output nozzle exploits what pressure is available.
The variable water nozzle maintains a constant hose retraction speed from the beginning to the end of the strip working in combination with an Ecostar 4300 or Ecostar 6000 controller.
Up to 12 different irrigation programmes that define retraction speed, pre-irrigation, post-irrigation and speed zones can be stored, and operating data is collected for transfer to farm records.
Bauer’s SmartRain cloud-based management system comes with a mobile device app with remote monitoring, alerts and control functions enabling managers and field staff to oversee the deployment of several irrigation reels.
A selection of rainguns and booms with different nozzle sizes, types and installations caters for all crops, bed and field layouts, including Bauer’s Centerstar 9000 pivot irrigator with all options available to Burdens Group customers.
Drain maintenance is key
The link between blackgrass and poor drainage is as clear as black and white in some fields, with the well drained areas free of the weed, while infested areas clearly show the need for, or lack of, drainage.
According to Miles Drainage the problem could simply be a lack of maintenance. “With less full-time farm staff and more acres to farm, drain maintenance can unfortunately become easily overlooked.”
For a drainage scheme to operate to its full potential, the outfalls need to be in good condition and have a suitable freeboard – the difference between the drain invert and the ditch bed, says the company. Drains which are hidden in the undergrowth need to be found, cleared and marked with a suitable marker post, making them easier to locate.
Spring is also a good time to carry out drain jetting and it is never too early to start planning mole draining deciding whether it is to be undertaken through the growing crop, or after harvest, it advises.
Miles Drainage is based in East Anglia but operates nationwide. The company can provide a GPS based land drainage design and installation service to agricultural, equestrian and sports field customers. Miles Drainage manufactures the Single Leg Mole Plough as well as supplying spares and wearing parts.