Lateral move and centre pivot irrigation machines continue to stir interest among irrigators. The technology can stretch water further or extend irrigation into country unsuitable for surface irrigation.

Response by farmers to recent workshops suggests that after closer scrutiny of performance and economic costs, the machines have the capacity to change the irrigation industry.

The change has already occurred in the United States, where centre pivot and lateral move machines irrigate more than 30 per cent of irrigated land.

Responding to frequent requests for information, NSW Department of Primary Industries irrigation officers ran a series of workshops.

To help farmers reach independent, informed decisions, the workshops primed them with questions to ask their suppliers and highlighted key factors to be considered when contemplating purchase.

Eighty people attended the courses and their feedback suggests that investment in these machines will increase in future.

One of the greatest attractions is that well designed machines can considerably increase water-use efficiency by precise and uniform application of water and virtual elimination of any waterlogging.

But the systems do have their problems. Both systems have higher pumping and capital cost than surface systems.

Laterals also have double the maintenance requirement of centre pivots and require additional guidance and control systems which can be costly.

When investigating a machine, both capital cost and running cost should be examined.

Looking for the cheapest way in means many buyers allow the capital cost to sway their decision to buy something which turns out to be very costly to run.

The National Centre for Engineering in Agriculture found that an eight percent increase in capital costs can reduce running costs by up to two thirds over 15 years, while a 6.3pc increase in capital cost can often halve centre pivot running costs.

Negative aspects of these machines are outweighed by positive aspects, if a 2001 survey of lateral move and centre pivot irrigators is any indication.

Ninety pc of centre pivot and lateral move irrigators surveyed intended to install another machine; 65pc own two or more.

Further information: Michael Grabham 02 6960 1333

This story appears in Agriculture Today.