Effect of chicken manure with roxarsone on growth andarsenic accumulation in vegetables

A pot experiment was carried out under greenhouse conditions to study biomass and arsenic contents of four vegetable crops (flowering Chinese cabbage, turnip, lettuce and crown daisy) at difference harvest stages. The aim of the study was to validate the effect of roxarsone in chicken manure on growth and arsenic accumulation of vegetables. Treatments with roxarsone-free chicken manure were used as control experiment. The results showed that biomass and arsenic contents of vegetable shoots and gross arsenic uptake in the four vegetable crops were enhanced with increasing growth period. However, arsenic contents of vegetable roots or tubers reduced with increasing growth period. At the same harvest stage, chicken manure with roxarsone reduced flowering Chinese cabbage, lettuce and crown daisy biomass but increased turnip biomass. Total arsenic content and gross arsenic uptake of the four vegetable crops treated with chicken manure with roxarsone were (significantly) higher at harvest stage than in the corresponding control treatment. Compared with the control, shoot arsenic contents of the four vegetable crops at final harvest stage treated by chicken manure with roxarsone increased by 10.53%, 5.56%, 11.11% and 11.11% and those of the roots increased by 52.94%, 46.67%, 39.22% and 28.00%, respectively. Also the gross arsenic taken up by the four vegetable crops under treatment of chicken manure with roxarsone increased by 7.07%, 30.88%, 15.25% and 5.57%, respectively. The results suggested that chicken manure with roxarsone somehow influenced the growth of vegetable crops. Although chicken manure with roxarsone increased vegetable arsenic uptake and accumulation, its effects on different vegetables were different. Arsenic intakes into edible parts of the vegetable crops treated by chicken manure with roxarsone were respectively 10.53%, 46.67%, 11.11% and 11.11% higher than that of the control if the same weights of the same vegetables were consumed in daily life. The result of this study provided important support data for vegetable growth in terms of the effect of adding roxarsone to livestock manure. It also laid the scientific basis for food safety of crops cultivated on livestock manure containing roxarsone.