Effects of biogas fertiliser application on the growth,heavy metal uptake and translocation characteristics of Amaranthus mangostanus L.

ZHANG Xu; ZHANG Tiejian; LIU Junliang; WU Hao

doi:10.16861/j.cnki.zggc.2025.0339

Abstract：To investigate the effects and ecological implications of applying biogas fertiliser on the cultivation of Amaran-thus mangostanus L.,this expreiment used,no fertilization as the control(CK)and established five biogas fertiliser appli-cation levels:0.10,0.15,0.20,0.25,0.30 L·kg-1,resulting in a total of six treatment groups.The study examined the ef-fects of different application rates on the growth,nutrient absorption,soil properties,and heavy metal content of Amaran-thus mangostanus L..The results showed that compared to CK,the biogas fertiliser application rate of 0.25 L·kg-1(BF-T4 group)significantly promoted the growth of Amaranthus mangostanus L..The total nitrogen,total phosphorus,and total potassium content in the plants increased by 13.7％,14.0％and 19.8％,respectively,all of which were the highest among the treatment groups.After applying biogas fertilizer,the proportions of soil-available Cr,As and Hg increased,while those of availble Cd and Pb decreased,none of which exceeded the soil safety limits.Biogas fertilizer enhanced the ability of Amaranthus mangostanus L.to accumulate heavy metals,with its bioconcentration factor(BCF)showing a positive cor-relation with the application rate of biogas fertilizer.This led to the total Hg content in the plant exceeding safety stan-dards,posing a safety risk.The results of logistic fitting indicated a significant positive correlation between the biogas fer-tiliser rate and TF-Cr,TF-Cd,TF-Pb,TF-As.The half cumulative effect coefficient EC50 showed that the order of influ-ence of biogas fertiliser on heavy metal absorption in the stems and leaves of Amaranthus mangostanus L.was Pb＞Cd＞Cr＞As ≥ Hg.In conclusion,the biogas fertilizer application rate of 0.25 L·kg-1 can significantly increase the biomass and nutrient content of Amaranthus mangostanus L.,contributing to the resource utilization of biogas fertilizer.However,it al-so indirectly enchances the accumulation of heavy metals in the aboveground part of the plants,making it unsuitable to cultivate Amaranthus mangostanus L.in the areas contaiminated with heavy metals of Cd and Hg.