改良剂连续施用对农田水稻Cd吸收的影响

Effects of continuous application of soil amendments on cadmium availability in paddy soil and uptake by rice

通过连续2a田间试验,研究了在Cd重度污染土壤上施用有机肥、石灰、石灰与有机肥配施1a后,第2a连续施用和不再施用改良剂对稻田土壤有效态Cd含量和水稻Cd吸收的影响.结果表明,有机肥、石灰单施及石灰与有机肥配施均能显著提高稻田土壤pH值,降低土壤中有效态Cd含量和水稻各部位Cd含量,第1a有机肥、石灰、石灰与有机肥配施处理的糙米中Cd含量较对照分别显著降低35.9%、69.2%和65.4%.与对照相比,第2a连续施用有机肥、石灰及石灰与有机肥配施处理下,稻田土壤pH值分别显著升高0.27、0.57和1.05个单位,土壤有效态Cd分别显著降低26.6%、29.7%和59.4%;糙米中Cd含量较对照分别显著降低63.1%、79.5%和83.6%,其中,第2a连续石灰与有机肥配施处理下糙米中Cd含量为0.20mg/kg,达到《食品安全国家标准食品中污染物限量》(GB2762-2017)中糙米限量值.第2a不再施用有机肥、石灰及石灰与有机肥配施处理的糙米中Cd含量较对照分别显著降低49.2%、69.7%和75.4%.双因素方差分析结果表明其值与连续施用改良剂的处理无显著性差异.上述结果表明,石灰与有机肥配施可有效降低污染稻田土壤中有效态Cd含量和水稻Cd含量,施加后一年内可不施或减少改良剂施用量.

A two-year field experiment was conducted to study the effects of organic fertilizer and lime on remediation of Cd-contaminated paddy soil. The application strategies of the soil amendments including continuous application and application only in the first year were compared. The results showed that the individual or combined application of organic fertilizer and lime both increased significantly pH and available Cd contents in the soil as well as Cd contents in different parts of the planted rice. The Cd contents of brown rice in the first year were reduced significantly by 35.9%, 69.2%, and 65.4% compared with the control, respectively. Under the continuous application strategy, the soil pH significantly increased by 0.27, 0.57 and 1.05 units respectively, the contents of available Cd in the soils decreased by 26.6%, 29.7% and 59.4% respectively and the rice Cd concentrations decreased significantly by 63.1%, 79.5% and 83.6%, respectively. Especially under continuous application of both organic fertilizer and lime, the rice Cd contents was 0.20mg/kg which had reached the National Standard of Pollutant in Food of China (GB 2762~2017). Under the strategy of application only in the first year, the Cd contents in the brown rice reduced significantly by 49.2%, 69.7% and 75.4%, respectively. The two-way ANOVA suggested no significant difference between the two strategies of continuous application and application only in the first year. The results indicated that the application of organic fertilizer and lime can effectively reduce the contents of available Cd in soil and Cd in rice, and the remediation effects can lasts two years without significant reduction after the first application.