秸秆还田对水稻镉吸收影响的整合分析

Meta-analysis of Effects of Straw Return on Rice Cd Uptake

【目的】我国农田土壤重金属镉(Cd)污染现状不容乐观,稻米Cd超标风险日益增加,而秸秆还田将秸秆富集的Cd归还至土壤,且还田秸秆腐解也能影响土壤理化性质进而改变Cd的生物有效性。探讨秸秆还田对水稻Cd吸收的影响及其影响因素,对于实现安全的秸秆还田措施具有重要意义。【方法】采用数据整合分析(Meta-analysis)方法,定量分析了不同土壤性质和秸秆特性等因素下秸秆还田对水稻Cd吸收的影响。【结果】秸秆还田能在一定程度上降低稻米、秸秆中Cd的含量,但影响不显著。强酸性土壤(pH<5.5)中秸秆还田能显著降低稻米Cd含量;土壤Cd含量低于0.8 mg/kg时,秸秆还田能够降低稻米Cd含量,土壤Cd含量超过0.8 mg/kg时,秸秆还田能增加稻米对Cd的吸收;土壤有机碳含量小于10 g/kg时,秸秆还田能增加稻米对Cd的吸收。不同类型秸秆还田未对稻米Cd吸收有显著影响,但秸秆还田量增加,秸秆还田对稻米Cd吸收的抑制作用减弱;秸秆自身Cd含量小于0.8 mg/kg时,秸秆还田降低稻米对Cd的吸收,当秸秆自身Cd含量大于0.8 mg/kg时,秸秆还田增加稻米对Cd的吸收;此外,当还田年限大于1年,秸秆还田能促进稻米对Cd的吸收。【结论】因此,实现稻田安全的秸秆还田措施应综合考虑土壤性质和还田秸秆特性。

【Objective】With the increasing pollution of cadmium(Cd)in farmland in China,a large amount of Cd accumulated in straw was returned to soil under straw return practice,and the decomposition process of straw could also affect the Cd bioavailability by means of soil properties,thus increasing the risk of rice Cd exceeding standard.Therefore,it is of great significance to research the effects of straw return on Cd uptake of rice plant and its influencing factors.【Method】The effects of straw return on rice Cd uptake were quantitatively analyzed by meta-analysis in the present study.【Result】The results showed that straw return could reduce the Cd uptake in rice grains and straws to some extent,but the effects were not significant.Straw return could significantly reduce the rice grain Cd concentration in strongly acidic soil(pH<5.5).When the soil Cd content was lower than 0.8 mg/kg,straw return could decrease the Cd content in rice grain,and when the soil Cd content was higher than 0.8 mg/kg,straw return could increase the Cd content in rice grain.Moreover,straw return tended to increase the rice grain Cd accumulation in soils with soil organic carbon content lower than 10 g/kg.In addition,different types of straw returning to field had no significant effect on Cd uptake in rice grains.However,with the increase of the amount of straw returned,the inhibitory effect of straw return on Cd uptake of rice grains was weakened.When the Cd content in straw was lower than 0.8 mg/kg,the uptake of Cd by rice grains was decreased,and when the Cd content in straw was higher than 0.8 mg/kg,the uptake of Cd by rice grains was increased.Besides,when the practice was lasted for more than one year,straw return could promote rice grain Cd uptake.【Conclusion】Therefore,for the purpose of safe straw return practices in paddy fields,the straw characteristics as well as soil properties should take into consideration in practical production.