Thiocyanate increases the nitrous oxide formation process through modifying the soil bacterial community

BACKGROUND Nitrous oxide (N 2 O) is a potent greenhouse gas depleting the stratospheric ozone. Previous studies reported that the thiocyanate (TC) excretion in the urine of cattle fed rapeseed meals containing glucosinolates was positively correlated with the N 2 O-nitrogen (N) emissions. The objectives of the experiment were to verify the effects and the mechanism of TC on the N 2 O-N emissions from the soil applied with artificial urine using static incubation technique. Four levels of TC, that is 0.00, 0.26, 0.78 and 2.33 mmol L −1 were composited in artificial urine as experimental treatments. Soil inorganic N and bacterial community were analyzed to elucidate the effects of TC on the N 2 O-N emissions of artificial urine. RESULTS Adding TC increased the N 2 O-N fluxes, the N 2 O-N to N application ratio, and the estimated N 2 O-N emissions from the soil applied with artificial urine both linearly and quadratically. The estimated N 2 O-N emission ( Y , in μmol) was increased with the TC adding level ( X , in μmol) in a quadratic manner: Y = 52.57 + 4.47 X − 0.123 X 2 ( R 2 = 0.70). Adding TC did not affect the soil bacterial diversity and richness, but increased the relative abundances of Nitrosomonas (both for nitrification and denitrification) and Hyphomicrobium , Lysobacter and Terrimonas (for denitrification), and tended to increase the relative abundances of denitrification and dissimilatory nitrate reduction to ammonium. CONCLUSION TC increased the N 2 O-N emissions of the soil applied with artificial urine possibly through enhancing the denitrification of nitrifiers in the soil. Field experiments are necessary to verify the laboratory results. © 2021 Society of Chemical Industry.