ABSTRACT
This is in fact the key reason why rice often contains much higher As than other upland crops (Zhu et al. 2008). We have been investigating the role of biogenic iron oxide in modulating As bioavailability in soil-rice systems. It has been shown that anaerobic nitrate dependent iron oxidizing bacteria in paddy soil can oxide ferrous iron under flooding conditions. As a result, the iron oxides sequestrate As, thus reduce As (and phosphate) bioavailability and uptake by rice plants (Chen et al. 2005). This is a proof of concept that manipulating anaerobic nitrate oxidizing bacteria can be explored to manage As in soil-rice systems, however, it is still at the beginning in capitalizing this option, as little is known about the microbial community responsible for iron oxidation, such as its diversity and population dynamics in relation to environmental conditions.
