Effect of Different Fertilizers on Ni Uptake and Distribution in Rice

Pot experiments were conducted to study the effects of 8 fertilizers (NH₄Cl, NH₄NO₃, Ca(NO₃)₂, CO(NH₂)₂, Ca(H₂PO₄)₂, KH₂PO₄, K₂SO₄ and KCl) on Ni uptake and distribution by rice. The results indicated that nitrogen and potassium fertilizers had little effect on the biomass and yield of rice, while the phosphate fertilizers significantly increased the biomass and yield of rice. The total amounts of Ni in rice were decreased by 12.3% - 38.8% after fertilizers were applied. Applying NH₄Cl, Ca(H₂PO₄)₂, K₂SO₄ and KCl significantly increased the concentration of Ni in the aerial parts of rice, whereas the rest 4 fertilizers decreased the concentrations of Ni in the aerial parts of rice. The concentration of Ni in the grain under maturity stage were 6.958 - 13.227 mg kg^-1 after fertilizer were applied, which increased by 41.03% - 168.11%, and had significantly exceeded the national food heavy metal limits hygienic standard (0.4 mg kg^-1). This study suggests that fertilizer application significantly increased the uptake of Ni of grain, and the effects of 8 fertilizers in the order: K₂SO₄ > KCl > Ca(NO₃)₂ > NH₄Cl > CO(NH₂)₂ > KH₂PO₄ > NH₄NO₃ > Ca(H₂PO₄)₂.