NEW IRRIGATION SYSTEM IN USE NEXT SEASON

Press, Volume CXV, Issue 33874, 20 June 1975, Page 17

NEW IRRIGATION SYSTEM IN USE NEXT SEASON

Big centre pivot irrigation units will be operating in Canterbury next irrigation season.

These units, with a moving sprayline up to hundreds of feet long, supported by towers, irrigate ’arge areas, of up to hundreds of acres at a time, with a minimum labour requirement which helps to offset their high initial cost.

Speaking to tjae Lincoln College farmers’ conference this year Mr C. B. Judd, a consulting agricultural engineer (soil and water) at the college, spoke of units irrigating up to 100 hectares or about 250 acres, being conjmon, and of some units that irrigated up to 200 hectares or about 450 acres. Mr R. S. Jarvie, sales manager for pumping and irrigation equipment for Andrews and Beaven, Ltd, said this week that 10,000 centre pivot units would be sold in North America this year. On some irrigation schemes, he said that there were as many as 700 of these machines operating. And Mr M. C. George, sales supervisor for A. M. Bisley and Company, said that in the United' States more land was irrigated by this method now than by any other means.

Mr Judd said that they were also popular in the Middle East. In Libya they .were being used on pure sand w’here lucerne was -being grown.

Two of the famous Valley units have arrived in a 40ft container for Bisleys and these are expected to be in operation in the province next season. With spray! ines about 1500 ft long, they are able to irrigate 180 acres at a time and cost about $40,000.

- “We hope to get more •than these/’ Mr George .said, “as there is more -interest than just for those already sold.” The interest, ' he. said, was not just confined to the South Island either.

The suppliers of this equipment, Valmont Industries, Ltd, are the largest manufacturers of centre pivot irrigation units in the world.

Quite a sizable local element will go into the units, including all of the pipe.

Andrews and Beaven will be importing hiGßOmatic pivotal irrigation systems — a big unit with a 1100 ft long sprayline which will irrigate about 80 to 85 acres at a time, and also a smaller portable unit that is particularly suited to small areas and paddocks of uneven shape, which can irrigate about six to 14 acres at a time.

The bigger unit is going to a farmer in MidCanterbury, who is going to shift it three times to

irrigate some 240 to 250 acres. The other unit is under offer to a Rangiora man who may eventually want four of them.

For a unit with a sprayline of about 1300 ft and watering about 130 acres at a time, Mr Jarvie said that the 'cost would be about $35,000. The smaller unit costs about $lO,OOO.

Andrews and Beaven intend to go into the manufacture of the equipment in New Zealand under licence using the imported units as a guide. Only 20 to 25 per cent of the components may need to be imported. But Mr Jarvie believes that for the bigger units the demand is likely to be limited. Still another firm. Wrightson NMA Ltd, are also interested in centre pivot equipment. Mr R. L. Winterburn, a technical representative of the firm, said this week that they were at present negotiating with overseas interests for supply of centre ’ pivot equipment.

A centre pivot sprinkler system consists of a single sprinkler lateral or spray line that has one end anchored to a fixed pivot structure while the other end is continuously moving in a circle around the pivot, Messrs D. G. Aldridge and D. H. Ryde, of the Winchmore irrigation research station, say in a recent issue of the “Journal of Agriculture.” Water is supplied to the lateral through the pivot from a well, irrigation canal or stream. Laterals vary in length, depending on the size of the circle to be irrigated. The lateral is supported by towers located between 25 and 75 metres along its length. The towers move on two wheels, either steei or rubber tyred, skids or tracks. Rubber tyres or tracks provide better flotation and traction than the steel wheels or skids, and are preferable in heavy soils where traction may be a problem. The Valley units being handled by Bisleys will have steel wheels while the Andrews and Beaven centra! pivot units will be mounted on rubber tyres. The mechanism for mov-i ing the lateral around the I circle is mounted on each' tower. There are four methods of powering the laterals — hydraulic water drive, hydraulic oil drive, air drive and electric drive. The main advantage of the latter three systems is that the lateral can be moved quickly to any part of the circle without the sprinklers working. The systems being imported by Bisleys and Andrews and Beaven will be

water powered. Mr George said that compared with the electric-powered units, which are widely used in the United States, the water-powered units were much easier to maintain — this could be done by a person with a Crescent adjustment spanner. Messrs Aldridge and Ryde said that the lateral or sprayline was kept in alignment by a system that speeded up a trailing tower or slowed down one that got ahead. The sprinklers along the sprayline are so organised that a uniform water application _is obtained along the whole line.

While overseas many of these units operate on only one site, they can be moved from site to site. One of the big advantages claimed for the system is its mimimal labour requirement and where they are not moved this is particularly low.

Messrs Aldridge and Ryde say that the time taken to shift a unit depending on its size and make, may be up to eight man hours, but Mr George spoke of the Valley taking about three hours to move. The Winchmore men say that the capital cost of these systems range from SUS2O,OOO to $U536,000, without a pump and motor, to irrigate a standard 48 hectare circle. And up to $lO,OOO would be required for a pump and motor. However on the basis of a unit costing $40,000 in operation in New Zealand, electrically driven and irrigating 144 hectares or about 360 acres on three sites, the Winchmore scientists concluded that the annual cost of owning and operating the unit — $43.08 a hectare, or 1.15 c per cubic metre of water applied, was highly competitive with other forms of sprinkler irrigation available in the country.

Mr Jarvie said that whereas a centre pivot unit might take eight hours to shift once every 10 days, the amount of’ pipe that would have to be shifted with a hand shift sprinkler system to irrigate the same amount of country would be some 12,000 ft or some 480 25ft lengths of pipe.

And Mr George said that while the centre pivot might involve a three-hour move once in 10 days, with other sprinkler systems and hour or two could he

taken up with moving pipes twice every day. Of importance these days, too. was the conservation of water achieved with the centre pivot systems, which applied it "efficiently.

Mr Judd noted that a problem' with the system was that it watered a circle so that unwatered gaps were left. To help overcome this problem Mr Jarvie said that their systems would have “big guns” on the ends of the spraylines, which in the case of the larger units would add about an extra 10 acres or more to the area watered. Mr Judd said that in addition to the low labour input and the elimination of pipe shifting, the advantages of centre pivot included its ability to make frequent applications of water where this was necessary and also its ability to operate over tall crops and to apply nutrients with the water. The units can also operate over undulating country. Seven local men There will be seven Canterbury men in the national ploughing cnampionships which will be decided tomorrow near Edendale—about halfway between Gore and Invercargill. Among the 22 finalists are two former national champions—A. J. Wallace, of Te Awamutu, who has the distinction of being runner-up in a world match in England a few years ago. and also- K. J. Taylor, of Clinton. The finalists are C. Agnew (Otane), G. Baird (Gore). R. Bennett (Reporoa), D. Brown (Temuka), G. Carter (Greenpark), P. Dixon (Rangiora), R. Dugdale (Waimate), R. Gifford (Blenheim), W. R. Hargreaves (Blenheim), R. Jessop (Feilding), A. R. Johnston (Rakaia). R. Lukies (Carterton). R. McKenzie (Balclutha), I. W. Miller (Gore), J. G. Pascoe (Aylesbury), N. Rowe (Palmerston North), N. Sheat (Palmerston), K. J. Taylor (Clinton), J. Thornton (Momona), R. Walker (Edendale). A. J. W'allace (Te Awamutu), and W. Winter (Rangiora).