This summer we began a new two year project investigating nitrate rates for process crops. Run in conjunction with McCain Foods, Heinz-Watties and Hawke’s Bay Regional Council with support from the Sustainable Food and Fibre Futures fund, this builds on work started under the Future Proofing Vegetable Production project.

Focusing on sweetcorn, tomatoes, beetroot and green beans, we are comparing current farm practice with either the “Nutrient Management for Vegetable Crops in New Zealand” guidelines or some alternative rate. 

The aim of this project is to validate the recommendations in the current best practice guide (“the book”) for one of the region’s largest industries. 

Along with comprehensive lab testing, a key tool we are using is the Nitrate Quick Test developed by the University of California – Davis and testing in New Zealand by Plant & Food Research. There’s helpful information on the FAR website. 

We have four plots of “grower practice” and four of an alternative which we are monitoring. Before any fertiliser is applied we do base measurements of the soil at three depths, covering the full root zone. Prior to side-dressing we repeat the tests to see how much nitrate is present. This takes into account any additions of fertiliser, mineralisation of organic matter and uptake by the crop. We repeat the measurements when the crop is harvested to see how much nitrate is in the crop, and how much is left in the soil. 

Many thanks to McCain Foods, Heinz-Watties and Hawke’s Bay Regional Council for co-funding, the farmers hosting trials, and MPI for financial support.