Novel gypsum-based products for farm scale phosphorus trapping (TraP)

The Trap project was a 3-year joint venture (2008–2010) analyzing the effect of gypsum, an industrial by-product, on phosphorus losses from fields to surface waters (Ekholm et al. 2011, 2012). SYKE was responsible for measuring nutrient loads in a small cultivated catchment, where fields were treated with gypsum in autumn 2008. Automated on-line sensors and traditional water quality sampling were carried out in two sites in the catchment. The results were up-scaled with the aid of the ICECREAM model (Jaakkola et al. 2012). The possible drawback of gypsum amendment, weakening of sediment ability to retain phosphorus by sulphate, was studied in a laboratory using systematic sediment incubations.

The project was lead by Yara Finland. In addition to Yara and SYKE, MTT Agrifood Research Finland, TTS Work Efficiency Institute and Luode Consulting Ltd participate in the project. The project is financed by Yara Finland and Tekes (Finnish Funding Agency for Technology and Innovation). Trap Follow-up project continued monitoring for yet another three years.

Cabbage field in our research area                      On-line sensor

Kaalipelto                   On-line sensor

Figures by Petri Ekholm SYKE

Rechearch area


Gypsum was amended on fields in autumn 2008 in a small (2.4 km2) catchment located in southern Finland.

Fig. Elina Jaakkola


  • Ekholm P, Valkama P, Jaakkola E, Kiirikki M, Lahti K, Pietola L. 2012. Gypsum amendment of soils reduces phosphorus losses in an agricultural catchment. Agricultural and Food Science 21:279–291.
  • Jaakkola E, Tattari S, Ekholm P, Pietola L, Posch M, Bärlund I. 2012. Simulated effects of gypsum amendment on phosphorus losses from agricultural soils. Agricultural and Food Science 21:292–306.
  • Ekholm P, Jaakkola E, Kiirikki M, Lahti K, Lehtoranta J, Mäkelä V, Näykki T, Pietola L, Tattari S, Valkama P, Vesikko L, Väisänen S, 2011. The effect of gypsum on phosphorus losses at a catchment scale. Finnish Environment 33/2011, 47 p.
  • Ekholm P, Valkama P, Jaakkola E, Tattari S, Kiirikki M, Pietola L. 2010. Does gypsum reduce phosphorus losses in an agricultural catchment? In: Turtola E, Ekholm P, Chardon W. 2010 (eds.). Novel methods for reducing agricultural nutrient loading and eutrophication. Meeting of COST869, 14–16 June, Jokioinen, Finland. MTT Science 10. p. 26.

More information

D. Sc. Petri Ekholm, Finnish Environment Institute,

Published 2014-04-09 at 10:28, updated 2014-10-21 at 16:01