Does the long-term application of calcium superphosphate lead to an increase of the soil rare earth element contents?
In order to test whether the long-term application of calcium superphosphate leads to an increase of the soil rare earth element contents, superphosphate fertilized soils were sampled and compared with superphosphate-free soils. Spectrophlame inductively coupled argon plasma atomic emission spectrophotometer (ICP-AES) was applied to quantify the rare earth elements (REEs). The total rare earth element contents in calcium superphosphate from Zhijin County, west part of Guizhou Province, China (produced by the sulphuric acid treatment of the apatites) are about 2.54 mg/g. Between 38 and 189 gREEs/hm2 per year (available for plants, estimated by 2% citric acid) will be introduced into the soil solution when applying 320 kg superphosphate/hm2 per year. The long-term application of the latter will increase the REE content by about 18% in the soil surface layer in these areas. A statistically significant increase of the content of the rare earths in some cultivated soils should not be neglected.
Zhang
Yun
Y
South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China. zhangyun@scbg.ac.cn
Deng
Li-Bin
LB
Ye
Wan-Hui
WH
D002130:Calcium Phosphates / Q000737:chemistry*; D005308:Fertilizers; D008674:Metals, Rare Earth / Q000032:analysis*; D012987:Soil / Q000032:analysis*
D002130:Calcium Phosphates; D005308:Fertilizers; D008674:Metals, Rare Earth; D012987:Soil; C494370:calcium phosphate, monobasic