A new project in the Hawke’s Bay is investigating the impacts of tile drains on horticultural land, to provide valuable
information about their effect on freshwater quality.
Horticultural tile drains are used to divert excess moisture from the soil. This can help waterlogged land become more
productive. This project seeks to understand whether this diversion of water contributes additional nutrients to our
waterways that may impact water quality.
The Ministry for Primary Industries (MPI), several key players in the horticulture industry, and Hawke’s Bay Regional
Council have kicked off a project to investigate this further. MPI is contributing $1.34 million towards the project
through its Sustainable Food and Fibre Futures (SFF Futures) fund.
“It’s a big knowledge gap currently and a potential issue that the sector is keen to examine proactively,” says Leander
Archer, Horticulture and Environment Consultant at AgFirst Consultants Ltd, which is leading the research.
“The horticulture sector wants to ensure that its nutrient use is efficient, and understand if the tile drains are in
fact impacting our waterways. If there’s no impact then great, we’ll have the data to prove it, and if there’s an impact
at certain times of year or when we face certain types of weather, we want to know about it so we can change our
management strategies.”
The project will collect data over three years on 16 commercial properties in the Heretaunga Plains in Hawke’s Bay that
are used for growing fruit and vegetables. It will set up two trial sites on each farm, enabling experimentation with
new management strategies in year three on one site, while leaving the other as a control.
“The Heretaunga Plains has been selected because it has extensive tile drainage networks and a range of groundwater
pressures and soil types, and much of the catchment is used for high-value horticulture. Plus, the Karamū catchment
within this area has reported water quality issues,” says Ms Archer.
“Horticulturalists want to grow healthy food that contributes to healthy communities, in a way that cares for the soil
and waterways that sustain us all. This research will help them to do that. If you don’t measure it, you can’t manage
it.”
Steve Penno, MPI’s director of investment programmes, says the outcomes of this research have the potential to provide
deeper insights into how the horticultural industry can become more sustainable.
“We all want clean waterways,” says Mr Penno. “The findings will be useful for other regions across the country as well.
At the very least we’ll gain more information about whether this is a problem we need to address. And at the most we’ll
identify the size of the issue and how to best measure nutrient losses to understand how to mitigate these.”
AgFirst Consultants HB Ltd is currently concluding the site selection process for the trial farms, for monitoring to
begin in Spring. Interested growers are encouraged to follow the project through their industry body or can get in touch
at hawkesbay@agfirst.co.nz.