With funding from MPI’s Sustainable Food and Fibre Futures fund, McCain Foods, Kraft-Heinz Watties and Hawke’s Bay Regional Council, we are testing nitrogen application rates on some of the most important process crops.
The purpose of this project is to retain the right to successfully grow process crops in Hawke’s Bay. This is under threat if new and anticipated regulations restrict nutrient use and make production unaffordable. Processors McCain Foods and Heinz-Watties represent about $1.8B of value and form the largest single employment sector in Hawke’s Bay. These low margin businesses compete on a global stage will not continue if on-farm production is restricted or costs increase.
Our goal is to have accepted best nutrient management guidelines for beetroot, sweetcorn, tomato and bean crops that optimise production and nitrogen fertiliser use efficiency, whilst minimising nitrogen leaching and CO2-equivalent emissions. Trial results will be published and able to inform regional and national best practice.
A comprehensive research plan has been developed covering the four key process crops. In the main comparison trials, each crop will be represented in four paddocks, with two paddocks included each year.
Paddock selection will be based on processor agronomist and grower knowledge of sites, seeking those where variability is expected to be low. The project team is considering which soil types to include.
Measurements will be replicated and for each crop, the overall set of paddocks combined for analysis as one trial. At these sites, the 2019 Best Practice Guidelines will be compared with either current practice or soil test driven nitrogen recommendations.
To ensure fertiliser application rates are known, farm application equipment will be calibrated, with the added benefit of knowledge transfer to the grower and staff.
Nitrogen pools including soil mineral N, mineralisable N, crop yield N and crop residue N will be measured, budgets prepared, and losses estimated. Pre-plant the soil will be sampled to the standard 150 mm depth and samples sent to commercial laboratories for testing.
Mineral N tests using the Nitrate Quick Test will be conducted at a series of profile depths (0-15, 15-30, 30-60 depending on site) before planting, and before any side-dressing and after the crop is harvested. Available nitrate levels will be calculated using the FAR Nitrate Mass Balance calculator.
Standard yield quantity and quality assessments will test for crop yield differences.
Plant tissues will be harvested, oven dried, and dry mass determined. Samples will be sent to commercial laboratories for nutrient testing.
Key metrics will be analysed statistically using ANOVA, unless data show an alternative to be more robust.
Unfortunately, 2022-2023 was a disaster season, and almost all the trial sites we established were destroyed by Cyclone Hale, the next massive rain event, or Cyclone Gabrielle. Of 11 trials set up this season, only one was successfully harvested and analysed.