Effect of dolomite and biochar addition on N(2)O and CO(2) emissions from acidic tea field soil

A laboratory study was conducted to study the effects of liming and different biochar amendments on N(2)O and CO(2) emissions from acidic tea field soil. The first experiment was done with three different rates of N treatment; N 300 (300 kg N ha(-1)), N 600 (600 kg N ha(-1)) and N 900 (900 kg N ha(-1)) and four different rates of bamboo biochar amendment; 0%, 0.5%, 1% and 2% biochar. The second experiment was done with three different biochars at a rate of 2% (rice husk, sawdust, and bamboo) and a control and lime treatment (dolomite) and control at two moisture levels (50% and 90% water filled pore space (WFPS)). The results showed that dolomite and biochar amendment significantly increased soil pH. However, only biochar amendment showed a significant increase in total carbon (C), C/N (the ratio of total carbon and total nitrogen), and C/IN ratio (the ratio of total carbon and inorganic nitrogen) at the end of incubation. Reduction in soil NO(3)(-)-N concentration was observed under different biochar amendments. Bamboo biochar with the rates of 0.5, 1 and 2% reduced cumulative N(2)O emission by 38%, 48% and 61%, respectively, compare to the control soil in experiment 1. Dolomite and biochar, either alone or combined significantly reduced cumulative N(2)O emission by 4.6% to 32.7% in experiment 2. Reduction in N(2)O production under biochar amendment was due to increases in soil pH and decreases in the magnitude of mineral-N in soil. Although, both dolomite and biochar increased cumulative CO(2) emission, only biochar amendment had a significant effect. The present study suggests that application of dolomite and biochar to acidic tea field soil can mitigate N(2)O emissions.