Abstract:
To clarify the effect of a single application of normal amount of organic fertilizer or lime on the reduction of Cd in early and late rice and its regulating factors, the acid-purple mud farmland with moderate Cd contamination was selected, and the commercial organic fertilizer treatment fermented by chicken manure and the quicklime was set up at a single time in the early rice. The concentration of Cd in different parts of rice, the extracted Cd (DTPA−Cd) of soil diethylenetriamine pentaacetic acid, and soil physicochemical properties were investigated for two consecutive seasons. The effect, duration, and influencing factors of Cd reductionin rice with organic fertilizer or lime were examined. Compared with the control, the Cd concentration of early and late rice brown rice is reduced by 44.4%, 11.8% for organic fertilizer and 72.6%, 34.7% for lime treatment, respectively (
P<0.05). The reduction rate attenuates gradually. A single application of organic fertilizer or lime also increases the soil pH by 0.40 and 0.48 units, but decreases the soil DTPA DTPA−Cd content by 13.6% and 8.26% (
P<0.05), respectively. In addition, a single application of organic fertilizer or lime significantlyreduces the Cd bioconcentration factor of the stem and leaf in early and late rice as well as the Cd bioconcentration factor of brown rice and the Cd translocation factor from rice roots to brown rice in early rice. A single application of organic fertilizer or lime also significantly improves the soil acid-base buffer capacity, alkaline hydrolysis nitrogen, available phosphorus content, and electric conductivity. A single application of lime and organic fertilizer improves soil acidification and soil fertility quality, reduces soil Cd effectiveness and the bioconcentration and translocation of Cd by rice plants. The effect gradually weakens with the extension of the annual growth time of double cropping rice. Practical applications should emphasize continuous and timely supplementary applications of organic fertilizers and lime to achieve sustained Cd immobilization, soil quality improvement, and reduced rice Cd accumulation.