Transcript GHD Template 2003 - Irrigation New Zealand

Planning Certainty
A challenge for Investment
April 2014
Tom Chesson – CEO Australian national Irrigators Council
Murray Smith – Principal Engineer, Agriculture and Regional Water (GHD)
Planning certainty
• Similarities and differences between New
Zealand and Australia
• Irrigation Corporations
• Water security – balance between water for
consumptive use and the environment
• Vegetation management
• Nutrient management (emerging focus in AUS)
Land Use changes
• Australia’s geological history and climatic condition (low rainfall
and high evaporation) has created a unique very flat continent
accumulated with enormous amounts of salts in the soil –
saline lakes/streams is a natural part of the Australian
landscape and native vegetation has adapted to these
conditions.
• Salinity - 2.5 M ha (potential to increase to 12 M ha); Acidity –
90 M ha (Williams, J & Saunders, D 2003, CSIRO)
• Land use change to agricultural land after European settlement
has resulted in clearing of native vegetation and changes in
landscape hydrology.
• Increase the need for water supply and fertilizer input to
support increased pasture and crop production.
• The system has now become vulnerable to leakage of
sediments, nutrients and water beyond root zone.
Nutrient Loss Risk factors
• Nutrient loss from farms can be costly and
has potential to cause degradation of
waterways, groundwater and add to
greenhouse gases.
• The major nutrients that cause
environmental pollution are:
• Nitrogen
• Phosphorus
Farm Nutrient Loss Index
To assess the risk of nitrogen and phosphorus loss for the
Australian grazing industries
• Industry standard to guide farm advisors on identifying risky
nutrient practices.
• Four nutrient loss pathways
Farm Nutrient Loss Index
• Key factors of FNLI that cause nutrient loss are:
1. source of nutrients
2. factors of nutrient transport
• “where there is a source of nutrient, there is a
potential source for nutrient movement off-farm”
Best Management Practices for
Nitrogen Application
General guidelines for N
management
– Reduced stocking rates and
stocking intensity to minimise
N losses from urinary
deposition.
– Only apply N when pasture is
actively growing and can utilise
the N.
– Avoid applying N fertiliser near
streams/riparian zones and
over drainage lines in a
paddock.
– Light N application is the best
practice - 50 to 60 kg N/ha in
any single application, 21 to 28
days apart.
Nitrate leaching and
denitrification
– Avoid the following practices:
• Over application – Nitrate leaching
• High rates of N on waterlogged
soils – Denitrification
• Application to soil at high
temperature - Volatalisation
– Free draining soils - avoid
application before heavy rainfall
and for at least 2 to 5 days after
heavy rains.
– Avoid pugging by heavy stocking
intensity during high rainfall
periods, as this will result in either
increased drainage or surface runoff loss of N.
Reef Rescue Water Quality R&D Program:
Overview of research projects
• Grazing industry
– Improving grazing management practices to enhance ground cover and
reduce sediment loads
– Runoff Nitrogen generation rates from pasture legumes – an
enhancement to reef catchment modelling
• Sugarcane Industry
– Evaluating and improving A‐Class practices to control nutrient losses from
sugarcane
– Advanced drip and optimised furrow irrigation to minimise sediment,
nutrient and pesticide losses to the environment through deep drainage
and runoff from sugarcane and banana industries
• Horticulture Industry
– Minimising off‐farm movement of nitrogen in the north Queensland
banana industry
• Dairy Industry
– Validating the cost/benefits of improved fertiliser practices and
quantifying nutrient loads and pathways from irrigated dairy pastures