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Code of Practice For Nutrient Management

Appendix 3: Fertiliser Activities And Environmental Concerns

Nitrate leaching to groundwater
Indicator: Increasing nitrate nitrogen in groundwater
Note: Nitrate leaching is not easily measured by users so the emphasis should be on avoiding leaching by following best management practices such as nitrogen fertiliser application, animal grazing and dairy effluent irrigation rather than remedial action after it has occurred.

Possible cause Best practice for remedial action
Nitrogen input exceeding nitrogen uptake
  • Reduce nitrogen input.
    Fact Sheets 6, 9
  • Increase nitrogen uptake in plants by matching nitrogen applications to plant growth.
    Fact Sheet 9
  • Ensure low or excessive pH is not directly or indirectly restricting N uptake.
    Fact Sheet 9
  • Ensure pastoral growth is sufficiently abundant to cope with the uptake. Pasture should be at least 25 mm high (approx. 1000 kg DM per ha) before nitrogen is applied.
    Fact Sheet 9
  • Balance nutrients (fertiliser inputs).
    Fact Sheet 9
  • Avoid winter application of N when the temperature is low and /or it is wet.
    Fact Sheets 6, 9
High nitrogen application rates (e.g. greater than 200 kg N/ha/yr)
  • Reduce nitrogen input.
    Fact Sheets 8, 9
  • Ensure high nitrogen uptake by:
    Fact Sheets 8, 9
    • Timing for growth periods
    • Splitting dressings
    • Ensure appropriate placement
Applying nitrogen in a single application
  • Split the nitrogen applications so that smaller amounts are applied more frequently.
    Fact Sheet 9
Heavy rainfall (i.e. >20mm within a day of applying N) or irrigation within a day of applying fertiliser
  • Check weather forecast and avoid application if heavy rain seems likely.
    Fact Sheet 9
  • Avoid applying fertiliser when soil is above field capacity (i.e. puddles on the ground).
    Fact Sheet 9
  • Select a less mobile nitrogen fertiliser (containing ammonium N rather than nitrate N).
    Fact Sheets 5, 9
  • Apply fertiliser after irrigation (e.g. border-dyke irrigation) especially when ground cover is low (>80%).
    Fact Sheet 9
Permeable soils which can cause nitrogen leaching. (i.e. if puddles disappear quickly after heavy rainfall)
  • Apply smaller amounts of fertiliser more often.
    Fact Sheet 9
  • Reduce the amount of nitrogen applied.
    Fact Sheet 9
  • Select a less mobile nitrogen fertiliser e.g. Ammonium N rather than nitrate.
    Fact Sheets 5, 9
Nitrogen fertiliser not securely stored
  • Ensure nitrogen is contained within the storage area on an impervious floor.
    Fact Sheet 6
  • Protect stored N from rain.
    Fact Sheet 6
High water table present
  • Reduce amount of N applied per application.
    Fact Sheet 9
  • Match application to plant uptake.
    Fact Sheets 6, 9
Contamination from loading sites
  • Ensure no spillage when loading in or out of storage, or into application equipment.
    Fact Sheet 6

 

Contamination of surface water from fertiliser run-off
Indicator: Algal blooms/excessive weed growth – elevated nutrient levels (e.g. nitrogen and phosphate)

Possible cause Best practice for remedial action
Slope too steep for vehicle access or natural drainage lines running down to open water
  • Use slower release fertilisers, or split fertiliser applications. Apply smaller amounts more frequently.
    Fact Sheets 6, 9, 13
  • Develop and maintain riparian strips.
    Fact Sheet 9
  • Avoid applying fertiliser when the ground is saturated.
    Fact Sheet 9
  • Increase buffer distance between application site and the open water.
    Fact Sheet 9
High rainfall or irrigation within a day of fertiliser application
  • Check weather forecast and avoid application if heavy rain seems likely. Avoid irrigation in excess of field capacity.
    Fact Sheet 9
  • Use slower release fertilisers, or reduce the fertiliser application rates in wetter conditions.
    Fact Sheets 9, 13
  • Split the application rates. Apply smaller amounts more frequently.
    Fact Sheet 9
  • Apply fertiliser after irrigation (in the case of, border-dyke irrigation) especially when the ground cover is low (>80%).
    Fact Sheet 9
  • Check irrigation technique is appropriate for the crop.
    Fact Sheet 9
Less than 80% ground cover (e.g. pasture less than 25 mm high or approx. 1000 kg DM/ha)
  • Increase ground cover before applying fertiliser.
    Fact Sheet 9
  • Maintain resilient and productive ground cover that is capable of efficiently using the fertiliser.
    Fact Sheet 9
  • Plant row crops on contour.
  • Ensure pasture is not over-grazed (reduce stocking rate or grazing time).
    Fact Sheet 9
  • Avoid pugging damage.
    Fact Sheet 9
  • Install and maintain riparian strips.
    Fact Sheet 9
  • Surface incorporate, drill or directly apply fertiliser to the root zone.
    Fact Sheet 9
Saturated soils (puddles forming)
  • Delay fertiliser application until soil conditions improve.
    Fact Sheet 9
  • Use a less soluble or slow release fertiliser.
    Fact Sheets 9, 13
Excessive rates of application
  • Set realistic crop yield goals and apply fertiliser at times of maximum plant uptake.
    Fact Sheets 8, 9
  • Account for all sources of nutrients and apply nutrients in correct proportions.
    Fact Sheets 8, 9
Uneven application
  • Use equipment suitable for the conditions.
    Fact Sheets 3, 4
  • Use calibrated equipment and experienced operators.
    Fact Sheets 3, 4
Soil permeability low, soil cracking (macropores)
  • Improve soil draining characteristics (subsoiling).
  • Reduce soil compaction.
    Fact Sheet 2
  • Reduce stocking rate.
  • Split fertiliser application rates. Apply less fertiliser more often.
    Fact Sheet 9
Storage site too close (less than 50 metres) to open water
  • Improve the storage facility so that all fertiliser is effectively contained (under a roof).
    Fact Sheet 6
Loading site too close (less than 50 metres) to open water
  • Minimise spillage of fertiliser when loading into or out of storage.
    Fact Sheet 9
  • Move loading site away from open waterway.
    Fact Sheet 9
Outflow from tile drainage system
  • Apply fertiliser when tile drains are not running.
    Fact Sheet 9
  • Avoid application when soil is saturated.
    Fact Sheet 9
Drought (excessively dry soils allowing high surface run-off because of slow infiltration rate)
  • Delay applying fertiliser until sufficient regrowth has occurred after rain.
    Fact Sheet 8

 

Contamination of open water from direct application of fertiliser
Indicator: Algal blooms/excessive weed growth – evidence of elevated nutrient levels (e.g. nitrogen and phosphate)

Possible cause Best practice for remedial action
Aerial application
  • Use fertiliser with larger particle sizes (less wind effect).
    Fact Sheets 3, 4
  • Choose alternative aerial techniques to allow more precise placement e.g. use of GPS and GIS.
    Fact Sheets 3, 4
  • Use methods other than aerial application.
    Fact Sheets 3, 4
  • Use selective application techniques (cover part of the area).
    Fact Sheets 3, 4
Ground application close to open water (e.g. less than 10m away)
  • Allow a larger margin between fertilised area and open water.
    Fact Sheets 4, 9
  • Use application techniques that direct or specifically place the fertiliser.
    Fact Sheets 4, 9
  • Use fertiliser with larger particle size.
    Fact Sheets 4, 9
  • Erect a physical barrier/riparian strip around the water.
Wind speed greater than 5km/hr towards open water
  • Apply fertiliser when wind direction is away from open water.
    Fact Sheet 4
  • Use fertiliser products and application techniques that confine fertiliser to the target zone.
    Fact Sheet 3
  • Change application techniques e.g. drill fertiliser at planting rather than broadcast.
    Fact Sheet 4
Fertiliser particle sizes with poor ballistic properties (e.g. less than 1 mm in diameter for dry material)
  • Use fertiliser with larger particle sizes.
    Fact Sheet 4
  • Use application techniques that direct or specifically place the fertiliser.
    Fact Sheets 3, 4
Storage site within 50 metres of open water
  • Move storage site away from open water.
    Fact Sheet 9
  • Ensure the storage facility effectively contains the stored fertiliser (under a roof).
    Fact Sheet 6
Fertiliser loading/handling operations less than 50 metres from open water
  • Relocate the loading site away from open water.
    Fact Sheet 9
  • Use wind shelters around the loading site to contain fertiliser.
    Fact Sheet 9

 

Social/ third party effects
Indicator: Complaints from affected parties

Possible cause Best practice for remedial action Fact sheet
Use of dusty fertiliser
  • Use fertiliser with a larger particle size (dry material).
    Fact Sheets 4, 6
  • Use other forms of fertiliser (e.g. slurry/liquid/suspensions).
    Fact Sheet 4
  • Ensure the wind is blowing away from sensitive areas.
    Fact Sheet 4
  • Apply fertiliser only at agreed times.
Noise during fertiliser application
  • Change to quieter application equipment.
    Fact Sheet 4
  • Change time of day when fertiliser is applied.
    Fact Sheet 4
  • Change operational technique to reduce effects of noise on affected parties.
  • Apply fertiliser only at agreed times.
    Fact Sheet 4
Off-target contamination (solids and liquids)
  • Use fertiliser with larger particle size.
    Fact Sheets 4, 6
  • Use precise application techniques.
    Fact Sheets 3, 4
  • Apply fertiliser only when the wind direction is away from affected parties.
  • Apply fertiliser only at agreed times.
    Fact Sheet 4

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