Decreasing arsenic content in Italian rice. Progresses and constraints

The greater arsenic (As) accumulation in rice grain compared with other crops is well known and in the last years a good deal of work has been done aimed to set up effective strategies to limit As uptake by rice. Some proposals are focused on a fine tuning of the redox potential in paddy fields, particularly at selected points of the rice cropping cycle; some others involve the use of amendments to immobilize As on soil solid phases, or to hamper its uptake by rice plants. Several of these strategies have shown promising performances in controlled conditions (from pot trials up to relatively small experimental plots), however a few of them have been applied and tested at farm level. When the scaling up of the experimental strategies is tried, and when the scientists have to handover the methods to the farmers, the number of variables dramatically increases; some of them can be controlled, some others cannot. Moreover, attention must be paid to the pedoclimatic conditions and to the cultivars involved in the experiments, since not always a successful strategy can be directly transferred to different environments. Concerning Italian rice cropping, years of research have allowed to make a relatively clear portrait of the present situation, identifying the main critical points. Strategies with good performances have been set up in controlled conditions and have been tested up to farm level, identifying the main constraints emerging whit the scaling up of the methods and when setting them up in the producing context of the farm.