Fresh focus on efficient watering

The latest irrigation kit has been designed with energy and cost savings in mind.

From Greencrop: Irrimec ST7 hosereel and water gun. Credit: Greencrop Irrigation
From Greencrop: Irrimec ST7 hosereel and water gun. Credit: Greencrop Irrigation

The need to keep down fuel and water costs has always been a crucial factor for growers when selecting an irrigation system, but in recent years the issues associated with climate change have given the irrigation industry new challenges for the future.

According to a Defra report: "The predicted impact of climate change on UK weather patterns will increase the reliance on irrigation and is focusing attention on irrigation techniques that allow more efficient use of water.

"Increasingly, higher-value horticultural crops are grown in the UK under protected cropping. This increases yield quality but also provides opportunities both to save water and nutrient resources and to use modified supplies of these variables as regulators of growth and development."

Director John Rupp of Norfolk-based Greencrop Irrigation says: "It's a strange fact that rain is the most inefficient way to irrigate crops in this country.

"We either have too much at the wrong time or not enough at the right time - with irrigation you can control exactly when water is applied and ensure the right quantity."

New developments in irrigation techniques are giving growers more power over water use and more targeted irrigation for optimum crop yield.

Ian Flowerday, consultant to Field GB Irrigation, advocates using variable-speed pumps. "They give considerable savings," he says. "By being able to vary the speed of a pump, the amount of water going to different blocks of units can be controlled and the reduction in fuel costs can be up to 30 per cent."

He adds: "Every irrigation situation is different, but growers are discovering which techniques suit them best - and which are the most cost effective."

Flowerday says that higher temperatures in the future will not mean faster growth of crops."Basic requirements for crops are between 25mm and 30mm of water every week," he says. "Even with correct amounts of water higher temperatures can result in plant wilt and growth will be held back until the temperature drops.

"In very hot countries, spraying plants to keep the temperature down during hot periods is necessary. That may be something we have to think about in the future in the UK."

His records for Hampshire last year showed rainfall of only 2mm in April, 35mm in May and June and a record 136mm in July, dropping back to 34mm in August.

"These fluctuations mean we cannot predict what will happen during the course of a year, so irrigation control is vital," says Flowerday.

Water guns are often used in vegetable crops, but these are not the most efficient or economic way to use water, says Flowerday. "Dripper lines use 75 per cent less pressure and can provide up to 100 per cent efficiency in water reaching the plants," he says.

"Energy and water costs are major issues, but so is continuity of quality products for supermarkets. Dripper lines and solid-set systems give growers more control over irrigation."

Rupp believes that, in the long term, the east of England will experience serious water shortages and that growers will have to concentrate on installing more lagoons to store winter water for irrigation.

"Some growers are able to extract from rivers but in the future it may be harder to get extraction licences," says Rupp, who also thinks that remote-controlled systems, sensors and GPS technology are becoming standard equipment for growers needing to accurately place water.

He believes that around 15 per cent of all irrigation units are now fitted with remote-control units.

Greencrop supplies Irrimec hosereel irrigation systems with booms or guns and Otech linear systems, together with all pipes and fittings. It also designs systems and advises on irrigation requirements. "Different crops require different systems," says Rupp. "Water guns may be fine for potatoes and root crops but booms and sprinklers are better for lettuces and salad crops because you avoid splashing the plants with soil.

"Water guns are more efficient than they used to be and can be programmed to only get to the areas where water is needed. But it is booms that place water more accurately in vegetable crops and these days we have the linear systems that can cover the entire width of a field and be programmed to travel the length of the field at precise times.

"The ideal situation for growers is to have complete control with all the technology that is now available."

Latest launches

"The main developments in horticultural equipment this year focus on money and saving energy - plus being environmentally aware," says Flowerday.

New developments from Field GB Irrigation include a new Plastro Ultima twin-nozzled sprinkler system for solid-set field irrigation, designed to apply the exact amount of water for plant establishment - particularly where delicate growth is taking place.

White driplines and PR tubes from Plastro have been introduced after intensive trials in glasshouses and in the field. The tubes are multi-layered, with an inner black layer preventing light penetration and an outer layer for reflecting light.

They absorb less heat, lowering water temperature and causing less expansion and contraction along the length of the line, reducing the problem of dripper movement. As well as being UV resistant and highly durable, they reflect more light back to the crop - especially important is glasshouses. Because they are more visible, less damage is caused during cultivation and harvest.

Also recently introduced is the Ultima sprinkler for solid field irrigation, with two nozzles to ensure no back pressure (which occurs when using single-nozzle sprinklers) and the sprinkler and the stand are far more stable to give superior distribution of water.

The Ultima gives constant rotation speed at variable flow rates, with a good water distribution pattern. Variable trajectory covers high and low angles, depending on crop requirements.

Another new development from Field GB is the Supertif ND superior-flow regulated on-line drip system. The company claims it is ideal for pulse irrigation with a high resistance to clogging.

The Supertif ND offers a no-drain sealing diaphram which seals at 0.4 bar, invaluable for preventing sloping lines from draining. It is ideal for pulse irrigation with a high resistance to clogging.

Meanwhile, new systems have been developed by Revaho UK for growers to be able to install, remove and re-use their sprinkler and drip irrigation systems quickly and efficiently.

"Solid-set irrigation systems are being seen as a solution to the uncertain labour situation because they can be installed at relatively quiet times in the cropping cycle and operated with a minimal labour requirement," says Peter Robinson, technical support at Revaho. "Raingun-type systems require constant inputs to move them throughout the growing cycle."

Fast-retrieval systems cut down on time taken in the field. "These days the key phrase is 'effectiveness of operation'," says Robinson. "It's all about reducing input of water, labour and energy. Everything in horticulture is now geared to low-input systems, from cultivation and seed sowing to harvesting. Irrigation has gone the same way.

"We have to look at so many factors - applying water effectively and avoiding run-off," he adds. "Dripper lines are the most accurate way of getting water to the plants."

Dripper lines for crop irrigation come in two types - a thin tape for single-season use or a thicker-wall pressure-compensated re-usable dripper line that is designed to last from three to five seasons. Robinson says: "We have developed a hydraulically powered one-pass machine. It is designed for the recovery of re-usable dripper lines either pre- or post-harvest. These can then be re-installed into other crops or stored until required.

"The one-pass unit recovers the dripper line from the crop, cleans it and rewinds it onto drums. We've found that by using it to recover single-season dripper lines we can dispatch them to recycling in approximately one-third of the volume of existing recovery systems."

A Nelson machine to lay and rewind sprinkler laterals has also been developed. The sprinkler pipe is supplied on 2.2m-diameter drums, which are mounted in the machine. Pipe inserts spaced at the required sprinkler spacing enable quick connection of the sprinklers.

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