Effects of Phosphorus Fertilization on the Bioavailability of Arsenic in Soils

Effects of two kinds of phosphorus fertilizer including superphosphate(SP)and calcium magnesium phosphate(CMP)application on the growth of bok choy(Brassica chinensis)and bioavailability of arsenic in soils were studied through a pot experiment.The results in-dicated that application of SP and CMP could significantly promote the growth of bok choy.Compared with the control(CK)treatment,the biomass of bok choy increased by 149% and 119%,respectively.The biomass of bok choy for the treatments with high P application rates was more than that for the treatment with low P application rate for these two kinds of phosphorus fertilizers.It was more beneficial to increase the biomass of bok choy with the treatment of CMP than that of SP.Application of phosphate fertilizer could increase the amount of available arsenic in soils,the increased percentage reached 52.2% and 20.9% respectively for the treatments of high and low application rates of CMP,while those for the treatments of high and low application rates of SP were 15.0% and 5.5%.At the same level of phosphate application,the available arsenic content in soils was significantly higher for the CMP treatment compared with that of SP treatment.The arsenic amount ab-sorbed in bok choy significantly increased with application of phosphate application(P0.05),and the CMP treatment showed higher in-creased amount of arsenic absorption in bok choy compared with other treatments.Therefore phosphate application could increase the arsenic bioavailability in soils to certain degree,and it was more obvious for the CMP treatment.