Topdressing iron fertilizer coupled with pre-immobilization in acidic paddy fields reduced cadmium uptake by rice (Oryza sativa L.)

• Published in: The Science of the total environment Vol. 636; pp. 1040 - 1047
• Main Authors: Huang, Gaoxiang, Ding, Changfeng, Hu, Zhaoyun, Cui, Caihong, Zhang, Taolin, Wang, Xingxiang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.09.2018
• Subjects: Bioavailability; Cadmium; Hydrated lime; Iron plaque; Rice; Cadmium; Iron plaque; Bioavailability; Hydrated lime; Rice
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.04.369

Soil cadmium (Cd) contamination has become a serious problem in China. This study was conducted to test the effects of basal application of hydrated lime and iron fertilizer alone or together and topdressing of iron fertilizer at the tillering stage alone or coupled with basal application of hydrated lime, on reducing the accumulation of Cd in brown rice grown in an acidic paddy field slightly contaminated with Cd. The results showed that Cd in brown rice (BR-Cd) was dependent on not only the pH increase and CaCl2-extractable Cd reduction in the soil due to lime amendment but also Cd sequestration by the iron plaque on root surfaces. However, lime significantly decreased the amounts of Fe and Cd in the iron plaque on the surface of rice root. Topdressing of ferrous sulfate at the tillering stage resulted in the highest Fe and Cd sequestration in the iron plaque. Compared with the control (0.71 mg kg−1 BR-Cd), the basal application of lime and ferrous sulfate alone or together reduced BR-Cd by 45.8%, 18.3%, and 53.1%, respectively; topdressing of ferrous sulfate alone reduced BR-Cd by 23.6%, and topdressing of ferrous sulfate at the tillering stage coupled with basal application of lime yielded the lowest BR-Cd level with a 74.6% reduction. This result was further confirmed by field experiments at two sites in the following year. [Display omitted] •Lime application decreased the available Cd and dissolved Fe in the soil.•Iron plaque and Cd sequestration on rice roots was decreased by lime.•Tillering application of iron greatly enhanced iron plaque formation.•Basal lime application and iron tillering induced the lowest brown rice Cd level.