Drag hose for fields, filters for animal housing

How the agricultural sector can master the nitrogen problem

Drag hoses spreading slurry directly onto the field.Click to enlarge
Drag hoses spreading slurry directly onto the field.
Source: Stefan Thiermayer / Fotolia.com

The President of the Federal Environment Agency (UBA), Maria Krautzberger, made a plea for more protection of the environment in agriculture at the German Farmers' Day: "More and more consumers want not only tasty, healthy and affordable products but also products which do not put a strain on the environment. The organic food trend is a clear reflection of this. But conventional farming can make a big difference in this context, too. What concerns me at the moment are the excessively high levels of nitrogen emissions. Unlike other sources, agriculture has hardly reduced its nitrogen emissions for a number of years."

Germany had committed to a reduction of its nitrogen surplus to a maximum of 80 kilos per hectare of land by 2010 under the Federal Government's Sustainability Strategy. The roughtly 114 kilos per hectare recorded in 2011 clearly misses this aim. There is too much nitrogen (N) present as nitrate in virtually all groundwater. It is also responsible for the formation of harmful particulate matter.

Factory farming alone currently accounts for about 15% of the nitrogen emissions in Germany. Neighbouring countries like Denmark and the Netherlands have had good experience with filters required by law. Large fattening holdings in those countries must install exhaust air cleaning systems which reduce the nitrogen compound ammonia (NH3) and harmful bioaerosols. Although there are already over 1,000 such air cleaning systems installed on pig farms around Germany, in particular to reduce odour emissions in areas with high livestock density, it is not universally compulsory. "We need ambitious standards for factory farming throughout Europe which achieve visible reductions of nitrogen emissions. It is standard practice in industry – why not in factory farming? Exhaust air cleaning technology can reduce the ammonia emissions from animal housing by 70 to 90 per cent", said Ms Krautzberger.

The ammonia produced in the livestock industry not only smells unpleasant, it also transforms into harmful particulate matter when it reacts with other gases in the atmosphere.

Nitrogen emissions are not only produced in animal housing but also directly over fields and pastures when slurry, manure or fertilisers are spread. UBA's President Krautzberger advice is: "If lower-emissions techniques are applied in fertilisation, such as the well-known drag hoses which apply the nutrients directly above the field, nitrogen emissions can be cut significantly." It is also best if natural fertilisers like slurry and manure are ploughed under on untilled arable land without delay. The soil is then better able to absorb the nitrogen and less of it is released to the environment.

Too much nitrogen on fields is also a problem for groundwater. Whatever is not needed by soil and crops leaches into groundwater as nitrate. About 15% of the groundwater in Germany does not currently comply with the limit value of 50 milligrammes/litre (mg/l) applicable for drinking water. Nevertheless, the drinking water which is extracted from groundwater is fit for consumption almost everywhere. Only .08 per cent of drinking water samples recently exceeded the limit value of 50 mg/l. However, the water utilities are paying a high price for this. Many are diluting contaminated groundwater with uncontaminated water while others must extract the nitrate from the raw water through technical means because there is not enough uncontaminated groundwater in all regions. All of this is costly – a cost which ultimately is added to the consumer's water bill and is yet another argument for reducing nitrogen on fields.

Maria Krautzberger invited the German Farmers' Association to discuss controversial environmental issues more intensively with the Federal Environment Agency, pointing out that an ongoing dialogue can support an objective discussion of topics that may also be controversial.

Umweltbundesamt Headquarters

Wörlitzer Platz 1
06844 Dessau-Roßlau

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 agriculture  nitrogen emission  particulate matter  factory farming  ammonia emission  drag hose