Effect of the application of superphosphate on rare earthsʹ content in the soil

The total rare earth content in superphosphate produced by the sulphuric acid treatment of Kola apatites is ∼ 2.6 mg/g. The amount of rare earths (in forms usable by plants) transferred into the soil solution when 300 kg fertilizer/ha per year is applied has been evaluated to be 30–170 g/ha per year. A long-term use of such a superphosphate leads to a statistically significant increase of the content of the rare earths in the cultivated soils.