Vegetable Research & Innovation

The nitrate quick test mass balance tool

A nitrogen mass balance budget is a method to determine how much nitrogen fertiliser
should be applied to the crop to achieve its potential yield. However, for the budget to be
developed, estimates are required for the crop’s demand for nitrogen and how much of this
will be supplied by the soil.
Currently, there are two tests used to quantify soil nitrogen supply.

  • The mineral N test, which provides a measure of how much nitrogen is immediately available for plant uptake.
  • The anaerobically mineralisable N (AMN) test. This is an estimate of the N supply from the mineralisation of organic N.

For an effective nitrogen mass balance, both sources of nitrogen need to be measured. The
amount of mineral N in the soil can change quickly over a short period of time, especially as
crops take up nitrogen. It is useful to have quick and inexpensive methods for estimating soil
mineral nitrogen levels throughout the season. Previous work in New Zealand has shown
that Nitrate Quick Test strips are efficient and inexpensive.
This Guide provides guidance to growers on how to measure the soil nitrogen supply with
Nitrate Quick Test strips and make an informed fertiliser decision for the crop.