RESUMO
We investigate whether slag and biochar applications have subsequent effects on greenhouse gas emissions from paddy fields by applying biochar (B), slag (S), and a biochar-slag mix (BS) to paddy fields in the Fuzhou Plain, China. Applications of the three treatments along with a control (CK) of no amendment were made in 2015 before early and late rice seedlings were transplanted. Two years later in 2017, the CO2, CH4, and N2O emissions in the different treatments and control were measured in the early and late rice growing seasons. The results showed that, in the rice growing season, the averaged CO2 emission in the control, biochar, slag, and mixed applications were (1723.66±194.56), (1245.52±155.05), (1140.29±79.68), and (1055.83±62.13) mg·(m2·h)-1, respectively. The CO2 emissions from the three treatments were significantly lower than the control group (P<0.05), and the reduction ratios of each treatment to the control were 27.74%, 33.84%, and 38.75%, respectively. The averaged CH4 emissions in the control, biochar, slag, and mixed applications were (0.45±0.03), (0.40±0.05), (0.36±0.10), and (0.25±0.04) mg·(m2·h)-1, respectively, which were lower, but not significantly so (P>0.05), than the control. The ratios of CH4 emissions from each treatment to the control were 11.11%, 20.00%, and 44.44%, respectively. The averaged N2O emissions from the control, biochar, slag, and mixed applications were (62.47±27.00), (115.09±30.94), (79.75±24.98), and (112.68±23.59) µg·(m2·h)-1, respectively. In comparison to the control, the biochar, slag, and mixed treatments increased the N2O emissions by 84.23%, 27.66%, and 80.37%, respectively. The global comprehensive warming potential indicated that the application treatments increased the comprehensive warming potential of the early and late rice paddy ecosystems; after 2 years of applying slag and biochar treatments, their effect on the emission reductions were not obvious.