Overseen by AgFirst consultant Leander Archer, the project has been jointly funded by the pipfruit, cropping and kiwifruit sectors, with support from Hawke’s Bay Regional Council and the Ministry for Primary Industries (MPI).
Archer says while tile drains have long been part of land drainage solutions in some regions of New Zealand, little is understood about their impact, both positive and negative, on freshwater quality.
The project will collect data across 16 properties – eight pipfruit, four kiwifruit and four cropping – for the next three seasons, commencing this spring.
Site selection relied on having two trial sites on each orchard or farm, enabling researchers to trial new management methods in year three, once they have collected sufficient data to better understand runoff patterns.
The Heretaunga Plains lent themselves well to the project, with extensive tile drainage systems in place, and a varied and dense land-use across all the trial sites.
The trial includes the Karamu catchment, identified as one of six environmental hot spots by the Hawke’s Bay Regional Council, where water runoff has shown high levels of contaminants and sedimentation.
The plains also have a varied cross section of soil types and experience a range of groundwater movement.
“We hope that what we learn from the trials will provide information that can be applied across the country,” Archer said.
“Tile drains are common throughout NZ, with Gisborne being another horticultural area with a lot in place.”
Depending upon the level of data and information gathered over the first two seasons, the project managers hope to develop some management methods that can be trialled in the third season.
At this stage they are still calculating the total area the drains are effective over, but estimates are that figure is likely to be in the hundreds of hectares.
“Site selection took time because we needed to have a clear understanding of where the drains were on each site. However, there was a lot of interest and goodwill from growers, keen to learn more about the drains and their impact,” she said.
MPI director of investment programmes Steve Penno says the outcomes of the work have potential to provide deeper insights into how the industry can become more sustainable.
“At the very least we will gain more information about whether this is a problem we need to address. And at the most, we will identify the size of the issue and how to best measure nutrient losses to understand how to mitigate these,” Penno said.
