Vegetable production requires ongoing revision of farm practice to meet cost pressures and increasingly stringent demands from regulators and markets for enhanced environmental performance and water quality.
With support from the MPI Sustainable Farming Fund, industry and regional councils, we partnered with growers and our funders to develop and test new production techniques. The project drew on and supplemented recent and current research to develop new generation good management practices.
We had four main areas of focus:
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- precise nutrient prescription (how much is required)
Nitrate Quick Test test strip being compared to colour swatches on the container 
Soil samples ready for testing - precise application (is it going where it is needed when it is needed)
Ensuring the prescribed rate of fertiliser is applied - maximising retention (ensuring leaching is minimised)
Bucket testing irrigation to avoid over or under watering
- recapturing nitrates that move beyond the root zone (constructed wetlands and wood-chip bioreactors)
Installing a woodchip bioreactor to absorb nitrate from drainage water
In the end, we didn’t do work on wetlands or bioreactors through this project. We couldn’t find surface water that had sufficient nitrate to support a reactor despite widespread sampling in drains. There is certainly evidence of high nitrate levels in drainage water entering Lake Horowhenua, but it was not present where drains exited the cropping areas. There is now a major government funded regional project to put drainage water through a very large wetland, sited between the catchment including the vegetable growing areas and the lake.
We included previous LandWISE work such as On-Farm Fertiliser Calibration, Arawhata Sediment and Drainage, and other groups’ projects including current research on quick tests for soil nitrate, fluxmeter monitoring of leaching and the use of wood-chip bioreactors to strip nitrate from drainage water.
The research side was supported with considerable extension and training. We were aware that numerous computer based decision support tools have been developed, but we identified that many growers needed considerable support and upskilling to have the knowledge, capability and experience to effectively use them.
This project was funded by the Ministry of Primary Industries Sustainable Farming Fund, Horizons Regional Council, Gisborne District Council, Ballance AgriNutrients, PotatoesNZ, Vegetable Growers and LandWISE.
