Why use fertilisers??Why use fertilisers??

Why do farmers apply fertiliser?Why do farmers apply fertiliser?

All living organisms require some All living organisms require some basic chemical elements to function basic chemical elements to function i.e. to build DNA , cells walls etci.e. to build DNA , cells walls etc

The major elements required are;The major elements required are;– nitrogen, phosphorus, potassium, nitrogen, phosphorus, potassium,

sulphur, calcium and magnesiumsulphur, calcium and magnesium

Why do farmers use fertiliser?Why do farmers use fertiliser?

To over come nutrient deficienciesTo over come nutrient deficiencies To replace nutrients transferred:To replace nutrients transferred:

– off farm in production i.e. milk, meat, off farm in production i.e. milk, meat, wool,cropswool,crops

– to unproductive areas of the farm i.e. to unproductive areas of the farm i.e. effluent ponds, trackseffluent ponds, tracks

If any one of these elements is If any one of these elements is deficient deficient – grass will not grow grass will not grow – or will not grow as well as it could or will not grow as well as it could

What are the environmental problems What are the environmental problems associated with fertiliser application?associated with fertiliser application?

Phosphate runoffPhosphate runoff– Approximately 80% of the phosphate in Approximately 80% of the phosphate in

our waterways comes from agricultural our waterways comes from agricultural runoffrunoff

Nitrate leachingNitrate leaching– A study in the late 80’s indicated that up A study in the late 80’s indicated that up

to 20% of ground wells in Taranaki and to 20% of ground wells in Taranaki and Waikato had over 10mg/l nitrateWaikato had over 10mg/l nitrate

– The recommended maximum level is The recommended maximum level is 11.3mg/111.3mg/1

These affect water quality These affect water quality

By causing algal By causing algal blooms and blooms and excessive weed excessive weed growth whichgrowth which– stops us drinking itstops us drinking it– stops recreational stops recreational

activityactivity– stops us eating the stops us eating the

fishfish– and kills aquatic lifeand kills aquatic life

How do excess nutrients get How do excess nutrients get into waterways?into waterways?

Direct applicationDirect application– animals depositing directly in waterwaysanimals depositing directly in waterways– fertiliser spreaders applying too close to fertiliser spreaders applying too close to

waterwayswaterways

ErosionErosion– pugging & compactionpugging & compaction

RunoffRunoff– surface runoffsurface runoff– sub-surface runoffsub-surface runoff

LeachingLeaching

Nitrate LeachingNitrate Leaching

Dairy cattle numbers have gone from Dairy cattle numbers have gone from 2.9 million to 4.1 million in 20012.9 million to 4.1 million in 2001

N fertiliser use has gone from N fertiliser use has gone from 117,000 tonnes of N in 92/93 to 117,000 tonnes of N in 92/93 to 333,000 tonnes in 01/02333,000 tonnes in 01/02

What are the current figures?What are the current figures? A cows urine patch contains the A cows urine patch contains the

equivalent of 500-1000 kg N/haequivalent of 500-1000 kg N/ha

Nitrate Leaching cont..Nitrate Leaching cont..

At normal rates of application At normal rates of application leaching losses from nitrogen leaching losses from nitrogen fertilisers are typically 5-10% of fertilisers are typically 5-10% of nitrogen applied.nitrogen applied.

What can be done to minimise the What can be done to minimise the environmental effectsenvironmental effects

One option - Design a fertiliser plan for One option - Design a fertiliser plan for each farms specific needs.each farms specific needs.– This includes:This includes:

Nutrient budgetingNutrient budgetingGPS Soil & Herbage testingGPS Soil & Herbage testingFarm Environment MapsFarm Environment MapsUsing environmentally fertilisersUsing environmentally fertilisers

Sustain – an example of a more Sustain – an example of a more environmentally friendly fertiliserenvironmentally friendly fertiliser

Sustain is urea that has been coated Sustain is urea that has been coated in Agrotain & Sulphur.in Agrotain & Sulphur.– Sustain reduces leaching losses of Sustain reduces leaching losses of

nitrogen.nitrogen.– And also reduces ammonia volatilisation And also reduces ammonia volatilisation

losses to the atmosphere losses to the atmosphere

SustainSustain

Agrotain slows the breakdown of the Agrotain slows the breakdown of the urea.urea.– Urea breaks down over 0-2 daysUrea breaks down over 0-2 days– Sustain breaks down over 0-10 days Sustain breaks down over 0-10 days

Slowing the breakdown of urea gives Slowing the breakdown of urea gives the plant more opportunity to take the plant more opportunity to take up nitrogen therefore leaving less up nitrogen therefore leaving less nitrogen available to be leached.nitrogen available to be leached.