Thirty-one years already have passed since researchers started using isotope tracers on fields in France, following the fate of nitrates, according to an Oct. 21article by Bettina Boxall in the Los Angeles Times. They found that since their 1982 application, 61 to 65 percent of the nitrates had been taken up by plants. Much of the rest continued to reside in soil matter (12 to 15 percent) or was migrating into groundwater (8 to 12 percent).

Nitrates could affect groundwater “at least another five decades,” researchers concluded in the paper. “Therefore, attempts to reduce agricultural nitrate contamination of aquatic systems must consider the long-term legacy of past applications of synthetic fertilizers in agricultural systems and the nitrogen retention capacity of agricultural soils.”  FG

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—Summarized by FG staff from cited sources