Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Nitrogen emissions in dairy pastures peak in the springtime

The nitrogen emissions from boreal dairy pastures vary depending on the time of year and ley rotation. The emissions peak in spring, when the nitrates accumulated in the soil over the previous summer and winter leach with the melting snow.

Research Scientist Kirsi H. Saarijärvi of MTT Agrifood Research Finland charted the nitrogen emissions caused by intensive grazing in her doctoral dissertation. The topic has not been previously investigated to this extent in boreal conditions.

The experiments were conducted in a 0.7-hectare lysimeter field at MTT Agrifood Research in Maaninka, Finland. A total of 12 basins are placed underneath the field surface, and analyses of the leachates in these basins reveal the nutrient cycle in the pasture. A comparable pasture-size lysimeter field is not known to exist anywhere else in Europe.

The research also involved measuring the ammonia evaporated from the dung and urine of cows by using a chamber process.


Saarijärvi found that much more nitrogen is left behind on a pasture than in silage cutting fields, since the nitrogen outputs from the pasture are much lower than from silage cutting fields. Most of the nitrogen leaving the pasture is absorbed in the milk produced by the cows grazing in the pasture.

From an ecological perspective, the nitrogen leaching from the soil is the most significant load from dairy pastures.

“The second largest hazard to the environment arises from the ammonia (NH3) evaporating from cow dung and urine, but its volumes have been previously overestimated. The significance of nitrogen loss in surface runoff is low in the conditions prevailing in Finland,” Saarijärvi says.

Nitrous oxide is also emitted into the air from the entire field area, but its emissions are also lower than previously assumed.


Saarijärvi stresses that measurements must be carried out throughout the four-year ley rotation in order to gain a representative view of the nitrogen emissions. The nitrogen pulse is especially strong in springtime following pasture renewal.

“The nitrogen accumulated in the ploughed layer is released after pasture renewal. Emissions are smaller in the first years of the rotation, as the grassroots and soil microbes actively bind nitrogen,” Saarijärvi explains.

She found that the springtime nitrogen load is increased since the microbial activity in the soil is not entirely shut down for the winter but merely slows down. Therefore, nitrous oxide resulting from microbial processes in winter is emitted in large quantities as the soil thaws during the spring.

The nitrogen load is greatest in the areas where cattle spend most of the time in the pasture. The watering facility area functions as a congregation area, and it suffers treading damage that destroys the vegetation and soil pore structure, adding to local nitrogen losses.


The nitrogen emissions from dairy pastures can be reduced by several fairly simple techniques. Saarijärvi notes that emissions can be cut by reducing fertilisation, for example. A white clover mixture, which binds nitrogen directly from the air, can replace fertilisation in good soil conditions.

“The use of protein supplementation for cows should be reduced and the grazing season can be shortened slightly in the autumn. The hot spots of nitrogen cycling can be relieved by moving the watering facility area before the soil around it becomes damaged,” Saarijärvi suggests.

Where possible, it is best to sow the grass in the spring and to use a catch crop that effectively binds the nutrients.

The dissertation of Kirsi H. Saarijärvi, M.Sc. (Agriculture and Forestry), ‘Nitrogen cycling on intensively managed boreal dairy pastures’, will be publicly reviewed at the University of Kuopio on 19 December 2008. Professor Juha Helenius of the University of Helsinki will serve as the Opponent and Docent Helvi Heinonen-Tanski of the University of Kuopio will serve as the Custos.

For more information, please contact:
Kirsi Saarijärvi, Research Scientist, MTT Agrifood Research Finland, tel. +358 17 2644 822,

Ulla Jauhiainen | alfa
Further information:

More articles from Agricultural and Forestry Science:

nachricht Algorithm could streamline harvesting of hand-picked crops
13.03.2018 | University of Illinois College of Engineering

nachricht A global conflict: agricultural production vs. biodiversity
06.03.2018 | Georg-August-Universität Göttingen

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

A new kind of quantum bits in two dimensions

19.03.2018 | Physics and Astronomy

Scientists have a new way to gauge the growth of nanowires

19.03.2018 | Materials Sciences

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Science & Research
Overview of more VideoLinks >>>