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[October 23 AFP] with the nitrate manure used by large-scale farming, The paper which points out a possibility that the sequela of contamination remains for tens of years in soil or groundwater was announced by the U.S. science academy bulletin (Proceedings of the National Academy of Sciences, PNAS) on the 21st.
The superfluous existence of the nitrate within ? environment is related with drinking water contamination until now, and also causes rapid growth of an alga and has a possibility of doing damage to the marine organism of a freshwater ecosystem or the coast.
In order that the joint research team of ? France and Canada may show clearly what quantity of a nitrate remains according to agricultural work at a long period of time, Investigation for the field which uses wheat and a sugar beet as a chief crop was conducted in France, and a follow-up survey of the nitrate concentration in the soil of this field was conducted from 1982 to 2012.
Even if 28 year had passed after ?, as a result use of manure, it turned out that 12?15% of the nitrates originating in manure remain in soil.
On the other hand, it was taken into the plant about 61?65%, and had already leaked to groundwater 8?12%.
According to the ? paper, are “if most nitrates contained in manure are not used for vegetable growth, it tends to be considered to exude promptly from 根域”, but Some nitrates which remain in soil indicate “It is seemed that the situation which it is taken into crops for 50 more years with a nitrate, or will leak to groundwater at least from now on continues by it.”
In the past research done at the Mississippi (Mississippi River) valley which flows through ? U.S.-China southern part, in spite of having reduced injections of a chemical fertilizer, it is clear that the high-concentration nitrate remained in the river.
The authors of this paper say to the measure for returning ?, therefore land and a waterway to the original state, “You have to take the delay time resulting from the sequela of chemical fertilizer use of the past in an agricultural system into consideration.”