Adrian Hunt is a crop scientist at Plant and Food Research.

He recently completed a PhD at the University of Tasmania, investigating Pre-Harvest and Post-Harvest factor effects on the quality of onion bulbs exported to Europe for counter seasonal supply.  He now works across the vegetable and arable sectors to improve yield, profitability and environmental outcomes.

Together with colleagues Joanna Sharp, Paul Johnstone and Bruce Searle, Adrian has been investigating the value proposition for variable rate fertiliser application.

The technology to deliver variable rate fertiliser in an automated manner has advanced substantially in recent years. This has been aided by new or adapted spreading technologies coupled with location awareness using GPS (Global Positioning System). It is now technically possible to distribute fertilisers in a wide range of spatial patterns within a paddock, however the value proposition of variable rate fertiliser application is not thoroughly understood.

The Plant and Food team looked at the difference in productivity, profitability and potential environmental impact of a range of spatial management scales.

Based on a sampling grid of 105 points in a Hawke’s Bay paddock and used mineral N and a N mineralisation assay to quantify the underlying variability in N processes/cycling within the paddock they “grew” both irrigated and unirrigated maize in the crop simulation model APSIM Next Generation for the 105 sampling locations for 35 growing seasons, using long term weather data.

Adrian will present this work and the results at the LandWISE 2017 Conference in Havelock North.