DENMARK - A new DCA report shows that nitrogen, phosphorus and potassium surpluses in farming have decreased steadily over the last 20 years. The largest reductions took place until the mid-00s, when the reductions started to tail off.
Losses of nutrients such as nitrogen, phosphorus and potassium may have a detrimental impact on the environment, which is why the surplus and utilisation of at least the first two nutrients may be a good indicator of the environmental impact of agriculture.
The DCA – Danish Centre for Food and Agriculture produces an annual report of the nutrient balances in agriculture for the three nutrients over the last 20 years.
The latest edition – covering the years from 1992/93 to 2012/13 – has just been published and the conclusion follows the trend of the previous years’ conclusions: The nutrient surplus from farming has been steadily decreasing in the last 20 years, with the largest reduction until the mid-00s when the development seemed to tail off.
For the whole period the nitrogen surplus has been reduced by 43-46 per cent, while the reduction for phosphorus and potassium is 67 per cent. Compared with the last five years, the nitrogen surplus in 2012/13 was reduced by 0-3 kg N per hectare, the surplus of potassium fell by 1 kg per hectare whereas the phosphorus surplus increased by 0.8 kg per hectare.
Largest reduction before the mid-00s
The nutrient balance is measured at a national level, where the surplus is calculated from the balance between inputs and outputs.
More specifically, the initial calculation – using statistical data – involves summing the inputs of the respective nutrient in inorganic fertiliser, organic waste, air pollution, nitrogen fixation and the import of feedstuffs. From that figure will be deducted the nutrient amounts removed in plant and animal products and in the export of live animals and animals sent for destruction.
The difference between the two figures represents the nutrient surplus. The lower the surplus, the lower the risk of loss and thus potential adverse environmental impact.
In the short term – i.e. the last five years – the development in the nutrient surplus has been influenced by the high yields in the years 2008/09 and 2009/10, which resulted in a larger export of nutrients. At the same time, consumption of particularly phosphorus and potassium in inorganic fertilisers was unusually low in 2008/09, resulting in low surpluses in those years. Crop yields and the use of inorganic fertiliser have been more "normal" in recent years.
The report, prepared as part of the contract for policy support between Aarhus University and the Ministry of Food, Agriculture and Fisheries tracks the development of the surpluses of nitrogen, phosphorus and potassium year on year since 1992-93.
You can view the full report (in Danish) by clicking here.
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