Feeding the world’s growing population

New Zealand’s reputation as a quality food producer is growing.

Optimising food production

Over the next 50 years farmers around the world will need to produce more food than has been grown over the past 10,000 years.

Best use from a limited resource

Fertiliser helps farmers produce food efficiently by replenishing the soil. But fertiliser needs to be used responsibly.

Responsible and sustainable nutrient management

The Fertiliser Association invests in research and tools to ensure farm profitability while minimising nutrient losses to the environment.

The Fertiliser Association of New Zealand promotes and encourages responsible and scientifically-based nutrient management.

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Step 3: Identify environmental risks and assess their significance

You need to identify the risks of environmental harm that might arise from nutrient management activities (e.g. fertiliser use, dairy effluent irrigation and cropping) and to decide which of these are important enough to need management to avoid, reduce, or mitigate them.

There are several different approaches to assessing environmental risks. Most land managers can use a simple system of assessing risks themselves but some may need more formal risk assessment if their industry organisation or Regional Council requires this.

The approach provided here will help you recognise and understand the inherent environmental risks associated with the main nutrient management activities. In some situations you may need a higher standard of proof that you have assessed risks more scientifically – e.g. regulatory authorities may require a more detailed assessment if nutrient management activities do not fit within the ‘permitted activity’ category and require resource consent.

Identifying ‘inherent risks’

For each land management unit you must assess the inherent environmental risks associated with the main nutrient management activities. Inherent risk means any risk that arises because of the activity and the location. If you have not divided the property into its respective LMUs then assess the inherent environmental risk for the property as a whole. Do not ignore an environmental risk because the land manager already uses good management to reduce it. This does not remove the inherent risk, it only shows that they have recognised it and responded to it.

Typical risks arising from nutrient management activities include:

  • contamination of ground and surface waters
  • undesired changes in soil nutrient status (i.e. increasing or decreasing beyond target levels)
  • fertiliser application to non-target land (i.e. spread beyond the target area, blown off target, etc.)
  • accumulation of non-nutrient impurities in the soil profile. 

Some land managers may need to consider environmental risk in special detail – e.g. when applying for resource consent to apply fertiliser in a way that is not a ‘permitted activity’ in their region. Such detailed risk assessments should usually be prepared by a consultant with specialist knowledge of nutrient management and environmental risks.

Inherent risks are largely governed by site factors and the amount of nutrient applied (i.e. risks increase as the level of nutrient inputs increases). A list of site factors to consider in evaluating inherent risk is provided in Table 1 below:

Table1: Site features that affect inherent environmental risks from nutrient use/application:

Site Features

Factors to consider in evaluating risks

Groundwater

  • depth to groundwater and direction of flow
  • the type and thickness of underlying sediments
  • potential for nutrients to reach and affect groundwater

Surface water bodies (e.g. streams, rivers, wetlands, lakes and dams)

  • distance from areas intended for fertiliser storage, handling and application
  • density of stream and drainage network
  • any places where stock can directly enter
  • susceptibility to frequent flooding
  • susceptibility to run off or leaching of nutrients
  • erosion

Soils

  • current nutrient status
  • soil structure, including susceptibility to compaction
  • current compaction status
  • presence or absence of soil pans
  • drainage characteristics, including artificial sub soil drainage
  • current heavy metal status
  • water holding capacity
  • organic matter content

Altitude

  • altitude range

Aspect

  • direction of slope e.g. north versus south facing

Climate

  • susceptibility to heavy rainfall or drought or other unfavourable weather event

Slope

  • steep, rolling or flat (increasing slope generally increases the potential for nutrient run-off)
  • natural drainage courses

Nutrient sources

  • single or multiple nutrient sources
  • current nutrient load status in waterways (streams, rivers, lakes and groundwater)
  • form of nutrient used

Neighbouring crops and land owners

  • proximity of sensitive crops on neighbouring properties
  • proximity of adjoining landholders
  • prevailing wind direction, strength and frequency

Biodiversity - native fauna and flora

  • proximity of target areas for fertiliser to any areas of native vegetation
  • sensitivity of those areas to the fertiliser being considered

Assessing significance

Having identified the environmental risks on the land, you need to decide on the significance of these risks.

In many cases the significance will be fairly obvious. For example, land managers applying nitrogen fertiliser regularly on highly permeable soils with a high water table are likely to be well aware that there is a significant risk of groundwater contamination. Land managers applying similar rates of nitrogen to impermeable soils with little groundwater do not need to be so concerned with groundwater contamination but may need to be aware of the risk of surface water contamination if heavy rain falls soon after fertiliser application.

For each risk identified on the property, think about the potential adverse effects and the likelihood that they will occur in the short (up to 1 year) to medium (3-5 years) term given the conditions on each of the LMUs. Are the adverse effects highly likely or quite unlikely? You could think about it like this:

Likelihood

  • If there is little chance of the effect happening (i.e. it is possible but not aware of it happening on this property) then the likelihood is low.
  • If there is some chance of the effect happening (i.e. it has happened in the past, but not often), then the likelihood is medium.
  • If there is a strong chance that the effect will happen (i.e. it happens regularly), then the likelihood is high.

Think also about the environmental consequences in the context of Regional Council and/or local community expectations. If the adverse effect happens, will the effects be major or minor? Will they be very localised or widespread? Will neighbours be affected? Will the effects be easy to fix or irreversible? You could think about it like this:

Consequences

  • If the effect is unlikely to cause real environmental damage, has minimal potential to affect other properties and/or would be easy to reverse, then you can call the consequence low.
  • If the effect has some potential to cause damage or harm, is reversible but could cause adverse effects in the surrounding environment (i.e. could affect neighbouring or downstream properties), then the consequence is medium.
  • If the effect has the potential to cause significant environmental damage or harm, both in the immediate area and surrounding environment, is difficult to reverse and likely to concern the community, then you must consider the consequence high.

At this stage, think only of the overall practice of the activities proposed – e.g. nitrogen or phosphate fertiliser use. Do not downplay the likelihood or consequence because the land manager will practice good management. You will allow for good management and risk mitigating measures, such as applying split dressings of nitrogen, at a later stage in the planning process.

Now you can decide whether the overall risks of nutrient management activities are highly significant or less important. Figure 3 below combines likelihood and consequence to decide the overall significance of any environmental risk.

Figure 3: Assessing environmental risk

Likelihood

Environmental Consequence

Low

Medium

High

Low

Low Significance

Low Significance

Medium Significance

Medium

Low Significance

Medium Significance

High Significance

High

Medium Significance

High Significance

High Significance

In other words, if the likelihood, consequences or both are low, then the risk is generally low. As the likelihood of adverse effects and/or the seriousness of these effects increases, the risk becomes more significant.

Any environmental risk with a combination of high or medium likelihood and high or medium consequences must be addressed in the NMP with best management practices chosen to minimise the risk.

Getting advice on activities and their risks

In many cases, you will already be aware of the environmental risks associated with production activities. If you are making major changes to production operations and you are not sure about the inherent risks, seek further advice. Sources of information and advice include:

  • Regional Council staff (or equivalent)
  • industry organisations – these may have their own standards, separate to any set or recommended by Regional Council
  • fertiliser company staff
  • other agribusiness consultants (e.g. agricultural, horticultural or forestry professionals)
  • other land managers – look for experience with similar production systems to the management under consideration

The Fertiliser Association of New Zealand and Dairy NZ funded development of the Nutrient Management Adviser Certification Programme (NMACP). This industry-wide certification aims to ensure that advisers have the learning, experience and capability to give sound nutrient advice.

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