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How to Manage Low Nitrogen Leachers in High Nitrogen Areas

Presentation to the Waimakariri Zone Committee

13 August 2018

The Context

1996 2006

Over the past 20 years at least, we have seen significant land use change; land use

intensification; population growth – and groundwater and surface water quality decline

Source: Google Earth Pro

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What To Do About Low Nitrogen Leachers

What do you want?

♠ Address effects of land use on water

♣ A solution that works

♥ A solution that’s fair

♦ Balance different, sometimes

competing interests

⸙ Social license

What do we want?

Flexible land use within environmental

limits

Source: Environment Canterbury

What To Do About Low Nitrogen Leachers

For a start:

All sectors reduce losses

All sectors to implement GMP

Set reductions on a risk-based framework

Risk level correlates to regulation level (♥ ♦ ⸙)

Look at problem holistically (♠ ♣)

Set meaningful timelines (♣)

Low leachers = Low risk = Less regulation

High leachers = High risk = More regulation

It’s not just about Nitrogen

What Does This Look Like?

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What Does This Look Like?The Framework – From the River Up (♠ ♣ ♦ ♥)

1. What N concentrations can a waterbody’s freshwater systems

‘live’ with – this must enable ecosystem health and drinking

water

2. Use the desired N concentrations to set total N loads for a

waterbody. This must account for attenuation of the land in that

catchment

3. Calculate the total allowable loss from the land (per ha) by

dividing the total N load by the hectares in the catchment of that

waterbody

4. Use that total allowable loss per hectare as a ‘floor’. This floor

represents long term sustainable N losses from land use

Framework needs to look at

land as a sustainable

resource intrinsically

connected to the water.

Attenuation accounts for a

weighting on the land’s

productive potential,

susceptibility to leaching,

proximity to waterways,

ecosystem services

What Does This Look Like?The Framework – Implementation

STAGE ONE (♠ ♣ ♦)

All farms operating under

GMP within two years

STAGE TWO

(♥ ⸙ ♣)

Losses ≤ the N floor• Require a FEP

• No further reductions required

• Can increase up to the floor

• Focus on these low leachers

reducing other contaminants (esp.

through FEP)

Losses > the N floor• Require a nutrient budget

• Require a FEP

• Reduce losses 30% below GMP baseline levels

within 10 years.

• No further losses once farm is ≤ floor

• Then set appropriate goals for further reductions

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What Does This Look Like?Framework: In A Picture

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