Effects of humic acid liquid fertilizer partial substitution chemical nitrogen fertilizer on cadmium migration and accumulation in soil-rice system
The aimed to clarify the effect of equal nitrogen amount of humic acid liquid fertilizer replacing part of chemical nitrogen fertilizer on regulating the migration and accumulation of cadmium(Cd)in soil-rice system.A pot experiment was conducted and five treatments set up as:no nitrogen fertilizer(CK),chemical nitrogen(CF)and different replacement ratios of chemical nitrogen(20％,45％,70％marked as HF1,HF2,HF3,respectively).The Cd-polluted paddy soil was used as potted soil and the effects of treatments on the soil available cadmium,cadmium absorption,transport and accumulation in different parts of rice plants were explored.The main results showed that both the nitrogen application and humic acid liquid fertilizer substitution treatments decreased soil pH and increased soil available Cd content in different degrees,and the soil available Cd content increased with the increase of humic acid liquid fertilizer substitution ratio,but the difference was not significant.The nitrogen application and humic acid liquid fertilizer substitution treatments promoted Cd absorption and enrichment in each part of rice plant,and significantly affected Cd transport between organs.Compared with CF treatment,HF2 and HF3 treatments significantly increased the TFleaf/stem of Cd by 90.00％and 190.00％,increased the Cd bioconcentration factor in leaf by 100.00％and 233.33％,reduced the TFbrown ricdrachis of Cd by 35.06％and 41.56％,respectively,and inhibited the Cd migration and distribution to rice.The nitrogen application effectively promoted the dry matter formation,compared with CF treatment,the appropriate substitution ratio(45％-70％)increased the dry matter weight,and HF2 treatment significantly increased the brown rice and aboveground dry matter weight by 26.82％and 23.03％,respectively,it was conducive to the rice yield formation.Under the experimental conditions,the suitable replacement range of humic acid liquid fertilizer(45％-70％)could increase the rice dry matter weight and effectively reduce Cd migration and enrichment to rice.
equal nitrogen replacementhumic acidpaddy soilcadmiummigration and accumulation
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