生物有机肥对土壤—水稻系统中Cd形态及迁移特征的影响

Effects of Applying Bioorganic Fertilizer on Chemical Form and Transport Characteristics of Cd in Soil-Rice System

[目的]探究稻田土壤中Cd形态转化与生物有机肥施用量之间的关系,及水稻植株体内各器官Cd的累积分配特征,以期为研究区提供经济安全的水稻生产指导方案.[方法]在湖南省长沙市红壤稻田进行了2a的田间定位试验,期间设置了0,10,20,30与40 t/hm2共5个生物有机肥施用量处理,在水稻成熟期采集土壤和水稻样品,分析了生物有机肥对Cd在土壤中形态变化、水稻器官中的分配以及持续效应的影响.[结果]①生物有机肥施用后可将土壤中酸溶态Cd钝化为可还原态Cd,降低了水稻体内Cd的累积、土壤根系间富集系数和茎秆籽粒间转运系数.②高施用量生物有机肥处理下2017和2018年土壤酸溶态Cd较CK均显著降低,最大减少幅度分别为22.42%和7.05%,Cd在水稻不同器官含量的分布为:根系>茎秆>叶片>籽粒.③水稻籽粒Cd含量受土壤酸溶态Cd的直接影响,且酸溶态Cd受pH值、土壤有机质和阳离子交换量的调控.[结论]施用生物有机肥可以提高Cd污染稻田土壤肥力和稻谷产量,降低土壤酸溶态Cd的生物有效性.综合总体表现,当施用量为30 t/hm2时,有机质含量为255.32mg/kg的秸秆生物有机肥可以发挥出较好的修复作用.

[Objective]The relationship between Cd morphologic transformation and bioorganic fertilizer application in paddy soil and the accumulation and distribution characteristics of Cd in rice plant were analyzed in order to provide an economical,safe,and a scientific basis for rice production in polluted areas.[Methods]A two-year field experiment for the red paddy soil was conducted in Changsha City,which was situated in the Hu’nan Province.The soil and rice samples were collected from five disposals(0,10,20,30 and 40 t/hm 2)in their maturation period.The morphologic change,distribution of Cd in rice,and continuous influence of bioorganic fertilizer were analyzed.[Results]①The application of bioorganic fertilizer can change the acid-soluble Cd into its reducible form in the soil,thus reducing the accumulation of Cd in rice and transferring the coefficients of the soil-root and stem-grain.②On employing a high concentration of a bioorganic fertilizer,the concentration of acid-soluble Cd was significantly reduced in 2017 and 2018;the maximum range of decrease was observed by 22.42%and 7.05%,respectively.The amount of Cd in different parts of the rice was observed to vary in the following order:roots>stems>leaves>grains.③The bioorganic fertilizer had an impact on the Cd content in the rice grains by regulating the factors(pH value,soil organic matter,and cation exchange capacity)that affect the acid-soluble Cd.[Conclusion]The application of bio-organic fertilizer can facilitate an improvement in the soil fertility and rice yields by reducing the biological availability of acid-soluble Cd in Cd-polluted paddy fields.In conclusion,when the applied amount was 30 t/hm 2,the straw bioorganic fertilizer with an organic matter of 255.32 mg/kg could play a better repairing role.