If you are using fertilisers on your land, it’s important to follow industry-agreed practices for managing them. 

These practices are documented in the Code of Practice for Nutrient Management and associated booklets developed by the Fertiliser Association. This includes the 4R fertiliser management approach:

The 4Rs What it means
Right place Keeping nutrients where crops and pasture can use them, away from waterways or other sensitive areas.
Right time    Making nutrients available when crops and pasture can utilise them.
Right rate Matching the amount of fertiliser to crop and pasture needs.
Right product  Matching the fertiliser type to crop and pasture needs.

The Fertiliser Association has useful resources for farmers on its website fertiliser.org.nz.

The two primary nutrients needed for productive plant growth are nitrogen and phosphorus. The table below outlines why they are used, where they come from and how they can harm the environment:


Why is it used?

Where does it come from?

Why can it be an issue?

Nitrogen (N)

N is required in greater amounts than any other soil nutrient. Soils in Otago are naturally low in N.

  • Fertiliser
  • Stock urine
  • Wastewater and industrial discharges
  • Applied effluent
  • N-fixing bacteria in legume root nodules
  • Rainfall

Any N in the form of nitrate that is not taken up by plants can easily be leached through the soil and enter waterways. High N contents in water can promote algal blooms which can be toxic and smother aquatic life. High levels of N in drinking water can also be harmful to humans and animals. 

Phosphorus (P)

P is essential for plant development. Soils in Otago are naturally low in P due to limited rock weathering.

  • Fertiliser
  • Applied effluent
  • Wastewater discharges
  • Weathering of rock
  • Airborne dust

P binds easily to the soil so it can be transported with eroded soil to waterbodies where it can enhance the growth of algal blooms, which can be toxic and smother aquatic life.


More information on phosphorus can be found on the Land Air Water Aotearoa (LAWA) website.