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Land Land use
Nitrogen from fertilisers and manure
The intensification of pastoral land use has led to a noticeable increase in the use of fertilisers and irrigation in high-producing exotic pastures, both of which have increased the environmental pressures on our waterways and groundwater.
The amount of nitrogen fertiliser used in New Zealand has increased by about 10 times since 1985 and doubled since the mid-1990s. This is in line with the findings of a 2004 report on agriculture in New Zealand. The report found that the use of synthetic fertilisers based on fossil fuels on dairy farms had increased in recent decades. This contributed to the doubling of energy inputs into the average New Zealand dairy farm over the past 20 years.
Nitrogen from livestock manure, which contributes around five times the amount of nitrogen to the land as nitrogenous fertilisers, has also steadily increased. This increase is consistent with the recent trend towards more intensive forms of farming in New Zealand, particularly dairy farming. The high density of grazing stock on dairy farms delivers more nutrients to the land than other forms of farming.
Sources of nitrogen and phosphorus in agricultural catchments, 1985–2004
Notes: N = nitrogen; P = phosphorus.
Data source: Ministry of Agriculture and Forestry.
Text description:
The above graph shows the changes in nitrogen and phosphorus inputs to agricultural catchments, measured in thousands of tonnes, between 1985 and 2004. Inputs include nitrogen and phosphorus from fertilisers and livestock manure respectively.
This information has come from the latest national state of the environment report Environment New Zealand 2007.
Last updated: December 2007
