含Cd根茬留田对土壤-水稻累积Cd的影响

Effect of Retaining Cd-containing Root-stubbles in Paddy-field on Cd Accumulation in Soil and Rice

为探讨根茬中Cd留田后的归趋及其对下茬水稻Cd积累的影响,该文通过盆栽试验,设置0(CK)、0.24%(SR1)、0.48%(SR2)、0.72%(SR3)(w/w)的含Cd根茬用量处理,研究含Cd水稻根茬留田对下茬水稻生长、吸收Cd和土壤Cd含量的影响,为Cd污染土壤管控及水稻的安全生产提供依据。结果表明,含Cd根茬对水稻生长有一定的促进作用,同时也提高了水稻的Cd含量,且在SR3处理水稻根Cd含量最高,与CK相比,SR3处理水稻根部Cd含量增加了86.90%。水稻各部位Cd含量的分布为:根>>茎≈叶>籽粒,籽粒中Cd含量均未超过可食用安全限值。与CK相比,含Cd根茬增加了13.27%~25.51%土壤总Cd含量,且在SR3处理达最大值1.23 mg/kg。含Cd根茬提高了土壤pH及养分含量,与CK相比,含Cd根茬处理下土壤pH提高了0.05~0.12个单位,有机质含量增加了8.55%~13.68%,碱解氮含量增加了11.24%~13.48%,速效钾含量增加了5.56%~14.16%。综上,含Cd根茬留田能提高土壤养分含量,促进水稻生长,同时也造成土壤Cd累积,增加了水稻根Cd含量。

This paper deals with the issues of cadmium(Cd)in rice-stubbles that were retained in paddy fields,under⁃lining the study of the pathways of Cd contamination and the effect of Cd-accumulation on the next-planting rice in order to control soil Cd pollution and safe rice production.A pot-experiment was thereby undertaken with Cd-contain⁃ing rice-stubbles set into pot soil in different cases:0.24%(SR1),0.48%(SR2)and 0.72%(SR3)(w/w),as well as control(CK).Results of the pot-experiment showed that stubbles containing Cd retained in soil had,in certain degree,an effect on promoting rice growth,meanwhile increasing Cd content in the rice;compared to CK,the highest Cd con⁃tent of the rice-stubble appeared in Case SR3,up 86.90%;the distribution pattern of Cd-content in different rice parts was in order of deceending magnitude:roots>>stems≈leaves>seeds,with Cd concentration of seeds being within the safe edible limit;and compared to CK,rice-stubbles increased the total Cd content of soils by 13.27%~25.51%,and in Case SR3 soil’s Cd content went up to the maximal value of 1.23 mg/kg.In general,the Cd-containing rice-stubbles led to the upgrading of pH and nutrient level of the soil,comparing to the control values,pH,organic matter,available nitrogen,and available potassium contained in soils increased by 0.05~0.12,8.55%~13.68%,11.24%~13.48%and 5.56%~14.16%,respectively.To sum up,Cd-containing rice-stubbles retention in paddy fields led to increases of soil nutri⁃ents,promoting rice growth,meantime could led to enhanced Cd accumulation of soil,resulting in a increase of Cd content in rice roots.