Measuring real time nitrate leaching from a Hawkes Bay onion Field

The primary objective of this project was to prove that successful real time ‘in situ’ nitrate measuring was possible using a nitrate sensor and that nitrate losses were relative to both climatic and management events.

The project has achieved this primary objective (measuring real time nitrate leaching losses to drainage water) and has shown examples of grower/crop management ’cause and effect’ using the live sensor data.

There was a strong linear relationship between nitrate sensor readings and laboratory analysis of the grab samples, giving confidence that the sensor can be calibrated to give an accurate measure of nitrate-nitrogen concentrations in real time. This provides growers with a real time indication of N leaching from their fields when drainage volume is also able to be measured.

This research has demonstrated links between farmer management practices, such as fertiliser application and/or irrigation, and nitrate-nitrogen concentration in the drainage water. It has also demonstrated links between uncontrollable climatic events (rainfall) and nitrogen losses to water.