Effects of Biogas Slurry Irrigation on Heavy Metal Contents in Soils

[Objective] This study aimed to investigate the effects of biogas slurry irri- gation on heavy metal contents in soils. [Method] A pot experiment was carried out to investigate the effects of biogas slurry irrigation on the accumulation of heavy metals in soils by measuring the contents of Cu, Zn, Pb, Cr and Cd in different soil layers. [Result] The results showed that original and 30-fold biogas slurry increased the contents of Cu, Zn, Pb, Cd and Cr in soils; Cr might partially reach an exces- sive level in a short term. Biogas slurry irrigation increased the downward migration velocity of Cu and reduced the downward migration velocity of Zn in soils. [Conclu- sion] Biogas slurry irrigation influences the contents of heavy metals, and long-term application of biogas slurry will lead to the accumulation of heavy metals in soils.