Abstract

ALVARENGA, Paula et al. Compost application and sprinkler irrigation lowers the risk of As and Cd accumulation in rice grain. Rev. de Ciências Agrárias [online]. 2022, vol.45, n.4, pp.191-200.  Epub Dec 01, 2022. ISSN 0871-018X.  https://doi.org/10.19084/rca.28418.

A field experiment was set-up near the Gévora River (“Las Vegas Bajas de Guadiana”, Extremadura, Spain), for 3 years, to evaluate how the application of compost from olive mill waste, influences the accumulation of As and Cd in rice grain under different irrigation systems. The deficit irrigation (sprinkler irrigation) was able to lower the accumulation of As in the grain, when compared to the flooding irrigation systems, achieving As concentrations in the grain more than 5-times lower in the aerobic treatments than in the flooding irrigation conditions. The As concentrations in the aerobic treatments achieved values below the regulated limits established by the European Commision (0.20 mg kg-1 in the rice grain, fresh material), and even below the limit set for white polished rice intended to produce food for infants (0.10 mg kg-1). However, a contrary effect was observed on Cd accumulation in the grain, which increased in the aerobic treataments. Compost application (80 t ha-1 in the first year), was able to counterbalance that negative effect, lowering Cd accumulation in the rice grain, relatively to the non-treated counterparts (e.g., a reduction from 0.080 to <0.010 mg Cd kg-1 in the grain, in direct seeding with sprinkler irrigation), without increasing grain As concentrations. It was possible to conclude that, the aerobic cultivation of rice, with the simultaneous application of a mature and stable organic amendment, can be considered a good solution to, simultaneously, lower the risk of accumulation of As and Cd in the rice grain.

Keywords : rice production; potentially toxic elements accumulation; flooding irrigation; deficit irrigation; soil organic amendment.

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