Effect of Soil Amendments on Arsenic Reduction of Brown Rice in Paddy Fields

There is an increasing concern over arsenic (As) contamination in rice since Codex Committee on Contaminants in Food (CCCF) discuss on maximum levels for As in rice in 2010. This study was conducted to reduce As concentration in rice by soil amendment treatments in paddy field soils contaminated by As. The selected four amendments were poultry manure, agri-lime, steel slag, and gypsum with the addition of 3% or 5% (w/w) on a dry basis. The As reduction effect could not be verified, as a result of the pot test by adding poultry manure to the paddy soil around the mine located in Yesan. Among the agri-lime treated rice cultivated pots, the As concentration increased up to 32.1%. On the other hand, the content of As in the sample pots treated with steel slag and gypsum decreased by 65.4% and 63.4%, respectively. On the basis of the results of these pot experiments, the field test was carried out in the As polluted rice field around the mine located in Yesan, and when the four amendments were treated, the As content in the brown rice reduced in all the amendment treatments compared with the control plot. The As reduction in brown rice of the amendment was confirmed to be higher efficiency by the order of gypsum greater than steel slag greater than poultry manure greater than agri-lime. As a result of pot experiments using paddy soil around the mine located in Seosan, As stabilization efficiency in rice and As reduction effect could not be determined by comparison to the control. From the rice cultivated from agri-lime treated pot, As concentration increased by 15.8% in rice. On the other hand, the As content of the pots treated with steel slag and gypsum decreased by 39.1% and 60.2%, respectively. In conclusion, distinguished As reducing effectiveness could be expected by soil amendment treatments for rice cultivation.