Seasonal effect on the load in soil and subsequent transfer of arsenic to rice

摘要

The BR 29 rice variety was cultivated in potted soil (Aeric Endoaquept) for four consecutive seasons, using As-contaminated water in the dry (boro) season and fresh water in the monsoon (aman), in order to observe the effect of alternate irrigation on the As loading in the soil and on its transfer to rice. Soil arsenic content increased significantly (p = 0.003 for the first boro season and 0.013 for the second boro season) after each boro season, whereas the soil As was found to have decreased significantly (p < 0.001) at the end of both of the aman seasons. The soil As was found to be significantly reduced (p < 0.001) at the end of the fourth cropping season (boro-aman-boro-aman). At the end of the fourth cycle, the arsenic loading was found to be almost unchanged. Arsenic in rice grains was detected only when As-contaminated water was used during the boro season. Moreover, the As accumulation in rice grains was lower in the second boro season of the four cropping season cycles.