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Case study

Bruce Searle: What lies beneath?

06 May 2021

“The diet of the locals mostly consisted of potatoes because in the highlands hardly any other crops could grow well. It got me thinking: ‘there must be better ways to grow vegetables as a crop’.”

When Bruce reached university age at 18, his parents encouraged him to return to New Zealand to find his Kiwi roots. He enrolled in the agricultural science programme at Lincoln University and majored in crops, as he believed it was an area of growth and the sector was better for the environment. 

He went on to do a summer studentship at the neighbouring Crop & Food Research institute (the predecessor of Plant & Food Research) in Lincoln, where he was involved in experiments gathering data for modelling of wheat and pea growth. Subsequently he completed a PhD where he studied the interaction of water and nitrogen supply on yield and quality of potatoes. From there he embarked on his path of vegetables research. Two decades later he is now the go-to scientist for different vegetable industries, trusted by both big players and small growers.

Currently, Bruce is leading the research of the Sustainable Vegetable Systems project (SVS), an unprecedented collaboration of all key vegetable industries in New Zealand that is funded by the Ministry for Primary Industries and the sector. 

As part of the project, his team have recently begun an investigation into nitrate leaching of broccoli, working with nine commercial growers across the country. Nitrate leaching is a naturally occurring process when nitrogen in the soil is carried off by rainwater and causes ecological harm to water bodies. 

“We want to know how much nitrogen fertiliser broccoli actually needs, so that we can minimise leaching. Broccoli is harvested only for the head, and a large amount of nitrogen is still stored in the unharvested stalk, leaves and the root system. We also need to understand how that contributes to subsequent crops.”

In New Zealand vegetable growers rotate their crops, this may be driven by market needs or the amount of nutrients in the soil. The SVS team are working to provide robust data to inform management decision enabling growers to match the nitrogen residues left in the soil with the best crop to prevent leaching. 

The research findings will be used to develop tools and improve current models to empower growers to manage this nitrogen usage and therein the estimated discharge below the root zone on their individual vegetable farm, with a wide range of factors being taken into account.

VegetablesOther vegetablesSustainable, resilient food supplyCrop optimisationSoil, water and climate


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