9 Oct 2014

Hill country irrigation poses challenges

2:11 pm on 9 October 2014

More hill country farmers are installing irrigation systems as they look for ways to increase their production but it's not without its challenges.

irrigator

Photo: PHOTO NZ

Irrigation New Zealand's project manager Paul Reese is co-author of a new guidebook to help farmers adapt irrigation for steeper slopes.

"It has particular challengers around water movement and the environmenal effects of that. There are two key issues. The first is the depth applied in relation to how much the soil can hold and the second one is the infiltration of getting that water into the soil.

The infiltration in particular is related to the irrigation intensity in terms of how much you're applying at any time. So you have to put the right amount of water on and get it in before it moves, basically. One of the issues is that on any one slope, there might be different soil depths, structure, all that scenario, so it's way more complicated to irrigate to a slope than what it is to flat land," he said.

Paul Reese said if pivot irrigation systems are used they also have to be adjusted for travelling over slopes.

"We've got some quite steep slopes, anything up to 25-degrees, that they are putting pivots on. That's the maximum slope that a pivot will walk across or walk up, but they've got to be designed right and there are all sorts of issues around angles or components within the pivot.

"There are gear box issues in terms of they might wear a bit more, but there are certainly design tools out there for moving dirt around and designing the whole sysem, not just putting it on and hoping for the best. You've actually got to design these things so they meet the specifications that the pivots are able to operate in," said Mr Reese.

AgResearch, Landcare Research and Aqualinc have also contributed to the guide, which has been supported by the Government's Sustainable Farming Fund.

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