• Posted on: 30/10/2021
  • 2 minutes to read

That’s the surprising question PSA delegate and AgResearch scientist Grant Rennie is working to answer.

He’s involved in a trial through the Our Land and Water National Science Challenge to see whether a crop of bananas on a Northland farm can mop up excess dairy nutrients.

“There’s a good possibility this could change our nutrient cycle on farm, the fact that these bananas are able to suck up so much potassium and nitrogen out of our effluent really could be a game changer,” Grant says.


The banana crop was planted two years ago. It’s also being assessed as a potential nutritious supplementary summer feed for cows in an area where droughts are expected to become more severe.

“In terms of feeding it to the cattle it could be a really good summer feed. We just need to look at what it complements once we’ve got a good handle on the nutritional value.”

While it’s still early days, and the banana plants are yet to be fed in the large quantities required, Grant says he and the farmer are excited by the initial findings.

“Things are looking promising so far. The banana plants are full of water, so in a dry summer cows would see it as a bit of a treat.”


Grant says the goal is to create a more environmentally sustainable farming system where nothing goes to waste.

He sees himself as a jack-of-all-trades researcher who looks at the impacts of farming practices on productivity, the environment and communities.

He says AgResearch is providing quality science to support the farming industry to achieve the goals  set out in legislation such as the Essential Freshwater package and our commitment to reduce agricultural greenhouse gas emissions.


While the industry is sometimes criticised for its environmental impacts, Grant has observed a different attitude from farmers.

“The farmers I have seen, they have such a connection to their land, they want to protect it more than anybody else.”

“It’s important that the industry is empowered to meet those goals. We need farmer-led solutions.”

The Hamilton-based researcher says there is amazing work going on at AgResearch and other Crown Research Institutes.

“Every scientist within the CRIs is passionate about the work they do and about making a difference for New Zealand. ”