16 March 2001

How solid set system does the business

in Yorks

By Wendy Owen

North-east correspondent

SWITCHING irrigation systems has allowed one Yorks-based potato grower to achieve higher yields and better quality.

But whats more, cost and labour savings should follow, says JSR agronomist, Neil Pratt.

He had a "solid set" mini-sprinkler irrigation system installed on a crop of processing potatoes at Woodhouse farm, near York last year.

"Unfortunately, the wet harvest meant that some of the potatoes under the new irrigation system could not be lifted. But sample yields were better than the previous year and a more even water supply reduced stress on the crop, improving fry colours."

The whole system took five men about two days to build. But much of that work was a one-off, he says. Some time will be needed to dismantle the system at the end of the year, but during the summer much less labour will be required.

"In other seasons, we have had a man virtually full-time just managing the rain-gun. Now it takes one person about 20 minutes to activate the start pump and irrigate the automated zones. The job can be done during the night, when evaporation levels are lowest."

Added to that, the reel and rain gun had not been effective on the sandy soils. Any water applied moved quickly through the soil profile and out of the rooting zone. A "little and often" approach was needed, says Mr Pratt.

Solid set and trickle systems were compared, based on a 10.5ha (26 acre) field. (see table). Boom irrigation was ruled out as it would not suit the size and shape of the fields or offer significant advantages over conventional irrigation methods.

The solid set system, comprising a sand filter, sprinklers, laterals and overground pipework would initially cost more than trickle. But the trickle method would need 40 rolls of tape/year from year two, costing an extra £4400/year and pushing the cost/ha substantially higher.

"The solid set system had several other advantages compared with the trickle irrigation set up," adds Mr Pratt.

"Undulations in the field mean the trickle system would require pressure compensatory tape, an additional expense also requiring extra labour.

"Solid set irrigation does not need to be installed at planting and therefore would not interfere with potato planting rates. It could be also used on the onion crop and there would be no need to dispose of tape at the end of the season. Neither is it affected by moderate field undulations.

"In the event of a sprinkler blockage or pipe leak, individual components can be easily replaced, whereas that would be more difficult with a trickle system."

Fertigation, the practice of delivering liquid fertiliser through the irrigation system, is another possibility with the solid set arrangement.

"It is an option which we may take up in the future," he says.

Onion opportunity

Mr Pratt plans to extend the solid set systems use to the onion crop, which is extremely water demanding and suffered damage from the large water droplets supplied by the rain gun. "The rain-gun could not keep up with the crops requirements."

COST COMPARISON

Solid set Trickle

Initial cost £16,594 £9,415

Cost/ha/yr £158.04 £462.84

Based on 10.5ha field costed over 10 years. Trickle includes £4400/yr tape cost from year 2.

WHY SOLID SET

* Little and often needed.

* Cheaper than trickle.

* Less labour than rain-gun.

* Quality and yield benefit.

Cost comparison

Solid set Trickle

Initial cost £16,594 £9,415

Cost/ha/yr £158.04 £462.84

Based on 10.5ha field costed over 10 years. Trickle includes £4400/yr tape cost from year 2.

WHY SOLID SET

&#8226 Little and often needed.

&#8226 Cheaper than trickle.

&#8226 Less labour than rain-gun.

&#8226 Quality and yield benefit.

Onion opportunity

Mr Pratt plans to extend the solid set systems use to the onion crop, which is extremely water demanding and suffered damage from the large water droplets supplied by the rain-gun. "The rain-gun could not keep up with the crops requirements."