WG4チェアの須藤重人氏（農業・食品産業技術総合研究機構・農業環境変動研究センター）および柴田晃氏（立命館大学OIC総合研究機構）のよるプロジェクト研究の成果をまとめた論文「Effect of dolomite and biochar addition on N2O and CO2 emissions from acidic tea field soil」がPLOS ONEに掲載されました。茶畑の酸性土壌に白雲石やバイオ炭を混入することにより、土壌の亜酸化窒素・二酸化炭素排出への影響評価を実施しました。実験の結果、バイオ炭の混入により、酸性土壌のpH値が上がり、無機窒素は減少、そして亜酸化窒素の排出量は低下しました。また、白雲石およびバイオ炭の酸性土壌への混入は、二酸化炭素の排出量を増加させる一方、亜酸化窒素の削減には効果的であることが判明しました。
要旨：A laboratory study was conducted to study the effects of liming and different biochar amendments on N2O and CO2 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 NO3–-N concentration was observed under different biochar amendments. Bamboo biochar with the rates of 0.5, 1 and 2% reduced cumulative N2O 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 N2O emission by 4.6% to 32.7% in experiment 2. Reduction in N2O 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 CO2 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 N2O emissions.
著者：Oo AZ, Sudo S, Akiyama H, Win KT, Shibata A, Yamamoto A, et al.
雑誌名：PLOS One 13(2) 2018年2月