Federated Farmers: Chasing hard data on irrigation effects

Based on their on-farm experience and observations, lots of farmers believe irrigation can boost soil carbon and soil water holding capacity.

Former South Canterbury Federated Farmers president Ivon Hurst is chairman of a research project that over the next three years will look to nail those understandings down with hard science and peer-reviewed data.

"Anecdotal evidence is not enough," Ivon says. "It has to be scientifically validated and that's the way forward for all future land management practices."

Project research will be led by Landcare Research's Dr Sam Carrick, and a range of extension activities led by Katherine McCusker, of the AgriBusiness Group. It will support improvements in the management of soils to reduce environmental impacts and enable more accurate estimation of nutrient loss.

Through field measurements and samples involving 48 farms in Canterbury the project will quantify whether, under medium to long-term irrigation, soil water holding capacity increases compared with the same soil, in the same farm system, but under dryland conditions.

Effects of soil type and the number of years soil has been irrigated will also be studied.
Better knowledge around irrigation scheduling and modelling of nutrient leaching is crucial not just for Canterbury but irrigated areas around the rest of New Zealand, Ivon says.

MPI, the guardians of the Sustainable Farming Fund purse strings, agree. Earlier this year they granted the research project just under $300,000, which will be backed by contributions in cash and kind from Federated Farmers, Environment Canterbury, Beef + Lamb, Irrigation NZ, Dairy NZ, Landcare Research, irrigation companies and others.

Ivon says initial conversations about the project stretch back several years, including Ian Mackenzie (former Federated Farmers National Board member), Dr Lionel Hume (Federated Farmers senior policy adviser) and Trevor Webb, a leading scientist with Landcare Research. There appeared to be a knowledge gap on the relationship between soil water holding capacity and length of time under irrigation.

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