Increasing the selenium content of agricultural crops : decisions and monitoring

In Finland selenium has been added to fertilisers for 20 years. This has been founded on comprehensive, long-term research and monitoring as well as measures undertaken because of the results. The addition of selenium to fertilisers in Finland may be considered an excellent example of good collaboration between companies, research and authorities which has improved the quality of Finnish food and raised the selenium intake from food to a sufficient level in view of human and animal health. In Finland the shortage of selenium in the nutrition of domestic animals was detected as early as the 1950s and 1960s. The issue became topical again in the 1970s, when the low selenium content in Finnish food had been proven in extensive scientific studies. The selenium intake of the Finnish population was below all recommendations. In December 1983 the Ministry of Agriculture and Forestry set up a Selenium Working Group to draft a proposal concerning the addition of selenium to the general fertilisers. Another task of the Working Group was to draw up a research and monitoring plan for observing the impacts of the added selenium on the soil, plants, feedingstuffs and foodstuffs of plant and animal origin. The selenium intake of humans and animals was also to be studied and monitored. The work group assessed the impacts of the added selenium and, where necessary, gave proposals for revising the selenium quantities to be added. In accordance with the proposal of the Selenium Working Group, selenium has been added to multinutrient fertilisers used in agriculture and horticulture. At first the quantity added was 16 mg of selenium per kilo of fertiliser for cereals and 6 mg/kg for grasses. In spring 1990 the Ministry of Agriculture and Forestry decided, based on a proposal of the Selenium Working Group, to lower the quantity of selenium to be added to solid multinutrient fertilisers to 6 mg per kilo of fertiliser, and the addition of selenium to other fertilisers was prohibited. This was done because the increase in the selenium content in cereals and selenium intake was higher than expected. There was also some uncertainty as to the possible environmental impacts of the added selenium in fertilisers. The reduction led to a considerable decrease in the selenium content of feedingstuffs, fodder cereals and domestic foodstuffs. The Finnish Fertiliser Act was amended in 1993, and the Decision of the Ministry of Agriculture and Forestry issued under the Fertiliser Act in 1994 also adjusted the maximum allowable quantity of selenium in fertilisers. Now 6 mg of selenium as selenite could be added to multinutrient and inorganic compound fertilisers intended for agriculture and horticulture. However, the decision did not concern EC fertilisers. In 1998 the Ministry of Agriculture and Forestry decided to commission the Agricultural Research Centre of Finland (later MTT Agrifood Research Finland) to carry out the selenium monitoring. The legislation on fertilisers was last amended on the basis of a proposal of the Selenium Working Group in 1998, when the quantity of selenium to be added to inorganic compound fertilisers for agriculture and horticulture was raised by a Decision of the Ministry of Agriculture and Forestry from 6 mg to 10 mg of selenite per kilo of fertiliser. Again this decision did not concern EC fertilisers. The decision was based on observations which showed that the selenium intake of domestic animals and humans had decreased, first as a result of the reduction in the selenium quantity in 1990, and then due to the decrease in the use of multinutrient fertilisers. The conditions for environmental support and restrictions on the use of phosphorus had already clearly reduced the use of multinutrient fertilisers so that the selenium quantity per hectare of arable land has been decreasing. The monitoring of selenium continues in Finland, but so far the Selenium Working Group has given no indications to the Ministry of Agriculture and Forestry of any need to adjust the selenium quantities in inorganic fertilisers in the upcoming Fertiliser Product Act.

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