Nitrogen surplus from agriculture has been excessive for 20 years

No sign of change up to 2017 in intensive livestock farming regions

Ein Traktor bringt Gülle auf einem Feld ausClick to enlarge
Groundwater is often contaminated with nitrate, one reason being fertilisers containing nitrogen
Source: countrypixel / Fotolia.com

The agriculture sector has a lot of catching up to do when it comes to reducing its nitrogen inputs, say the latest nitrogen soil surface budgets of the German Environment Agency (UBA) which are based on data up to 2017. The average nitrogen surplus of the nitrogen soil surface budget is 77 kg per hectare (kg/ha) and has remained virtually constant for more than 20 years. Increases were registered in Lower Saxony and North Rhine-Westphalia in districts with intensive livestock farming. The high nitrogen input comes from typical fertilisers such as mineral fertiliser and manure. Digestates from biogas production are also adding to the burden, now accounting for some 15 percent of the nitrogen used in the agricultural sector.

UBA 's President Maria Krautzberger said: "Germany 's own inaction is to blame for this situation. By doing too little for so long it should come as no surprise that the European Commission goes to court to demand compliance with regulations." Germany was condemned in 2018 by the European Court of Justice for violating the limits set out in the Nitrates Directive and ordered to take effective mitigation measures. The European Commission also judged Germany's 2017 amendment to fertiliser legislation to be insufficient and must therefore once again be revised. "If Germany fails to take action, substantial fines owed to the EU are impending - and we will still face high impacts on man and the environment," said Ms Krautzberger.

Nitrogen (N) is an elementary component of all living beings. Nitrogen is used as fertiliser in agriculture to increase yields. Excessive spreading of nitrogen has a considerable impact on water, climate, air quality and biodiversity, which is why UBA has been made calculations of nitrogen surpluses in agriculture for more than 20 years. The calculation of the national soil surface budget takes into account the amounts of nitrogen entering fields and pastures through fertilisation, seed and atmospheric deposition and the amount of nitrogen withdrawn with the harvest. The difference is the nitrogen surplus, which is also responsible for water pollution.

The updated soil surface budget at regional level, together with the livestock and biogas budget, are the components of the gross nitrogen budget. The nitrogen surplus from the soil surface budget accounted for an average 73 percent of gross surplus between 1995 and 2017. From 2015 to 2017, the average amount of nitrogen transported to biogas plants and then back to fields as digestates was around 574,000 tonnes, which corresponds to 15 percent of the total amount of nitrogen used in agriculture. This is compared to a 46-percent share for mineral fertiliser in the same time period. The regional impacts of biogas production on nitrogen soil surface budgets in the districts were recorded for the first time.

Mitigation measures can be implemented to reduce nitrogen surpluses effectively. "This would require spreading the nitrogen in manure and the digestates at biogas production plants in a way that prevents its escape as ammonia to the atmosphere and can be better absorbed by crops. The use of synthetic nitrogen fertiliser could then also be reduced. It might be worthwhile to limit animal husbandry and curb nitrogen fertilisation in areas where high nitrate levels are contaminating the groundwater," Ms Krautzberger recommended.

From 2015 to 2017, the average nitrogen supply to agricultural land in Germany comprised a total of 226 kg of nitrogen per hectare (kg N/ha) of utilised agricultural area (UAA), compared to a removal of some 149 kg N/ha UAA (65.8%). The result is 77 kg/ha of surplus nitrogen on land and in the environment, which corresponds to 34.2 percent of total nitrogen input. The surpluses of the nitrogen soil surface budgets of the federal states vary from region to region, ranging from 51 kg N/ha UAA for Brandenburg up to 108 kg N/ha UAA for Lower Saxony.

The nutrient reports for North Rhine-Westphalia, Lower Saxony and Schleswig-Holstein made it possible for the first time to take the transfer of manure between districts/federal states into account in the budget. In key regions with mass animal production, transports of manure led to reductions of nitrogen surpluses in some districts, whereas the receiving districts ended up with higher budgets (crop farming regions in eastern Lower Saxony and southern North Rhine-Westphalia).

Umweltbundesamt Hauptsitz

Wörlitzer Platz 1
06844 Dessau-Roßlau
Germany

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