Arsenic phytoextraction by Pteris vittata improves microbial properties in contaminated soil under various phosphate fertilizations

A greenhouse study was conducted to evaluate the phytoextraction of arsenic (As) by Chinese brake fern (Pteris vittata L.) from a highly contaminated Typic Haplustept soil treated with different phosphatic fertilizers (di-ammonium phosphate (DAP) and single superphosphate (SSP)). The fern was grown in two repeated growing cycles and the resultant changes in soil biological activities were examined in pot culture experiments. The biomass yield of the fern was recorded 8.17-12.33 g pot−1 in the first growing cycle and 5.73-10.90 g pot−1 in the second growing cycle. The fronds of P. vittata accumulated the highest quantity of As ranging from 2884 to 4504 mg kg−1 in the first growing cycle and from 2254 to 3803 mg kg−1 in the second growing cycle. The total As removal form the contaminated soil ranged from 19.4 to 44.5 mg pot−1 and 10.4 to 32.1 mg pot−1 in the first and second growing cycles, respectively. All the studied soil microbiological parameters were improved as a result of As phytoextraction in two successive growing cycles of the fern, for example, microbial biomass carbon, carbon mineralization, dehydrogenase activity, acid phosphatase activity, alkaline phosphatase activity and arylsulfatase activity were increased by 46, 38, 77, 37, 12 and 49%, respectively. The soil biological activities were improved as a result of decrease in the bioavailable pool of As by the action of phytoextraction. The phosphatic fertilizer management practices played a critical role in mobilizing As in the contaminated soil and thus enhanced the process of phytoextraction.