生物炭對土壤微生物群落結構與氧化亞氮代謝相關基因量之影響

Abstract

生物炭 (biochar) 為進行生質能源的過程中，生物質經過高溫裂解後產生富含碳的物質，因難以被微生物降解，掩埋於土壤可長期的增加碳蓄存 (carbon sequestration)。將生物炭施用於土壤中，有許多不同的影響，其中生物炭降低溫室氣體釋放機制尚不明確，由於土壤氣體的釋放與微生物有密切相關，因此，本研究利用土壤分層箱進行離地試驗，探討生物炭的添加對土壤微生物群落結構及與氧化亞氮生成合相關基因之影響。本試驗使用茶樹枝條生物炭配合有機質肥料設定控制土壤組 (control soil, C)、有機質肥料土壤組 (fertilization soil, F)、控制土壤生物炭組 (control soil with biochar, CB) 及有機質肥料土壤生物炭組 (fertilization soil with biochar, FB) 四種處理。土壤分層箱置於室溫孵育60天，第0、30及60天收取土壤樣品。土壤微生物分析包含菌落數、土壤酵素活性、變性梯度膠體電泳及磷脂質脂肪酸。氧化亞氮生合成相關基因選擇nosZ、norB以及nirS，利用PCR及電泳測定基因表現量。結果顯示，添加生物炭可有效提升土壤菌落數及去氫酶活性，說明生物炭能有效促進土壤微生物的生長。由於生物炭可提升土壤之酸鹼值，因此，CB及FB處理的酸性磷酸脂酶活性顯著較低。由變性梯度膠體電泳結果顯示，生物炭的施用會改變細菌結構，而真菌結構的改變受有機質肥料影響較大。而氧化亞氮基因表現結果中，nosZ的基因量在添加生物炭的處理組中有增加的趨勢，而norB的基因量則下降，此兩基因量的變化可能為生物炭的添加具有降低氧化亞氮釋放的潛在因素之一。利用土壤分層箱進行的離地試驗結果為，添加生物炭可促進土壤微生物生長、改變細菌群落結構、提升nosZ基因量及降低norB基因量。

Biochar is a carbon (C) rich material produced by the thermo-chemical pyrolysis of biomass, a final product of bioenergy production. It is being considered as a potentially significant means of C sequestration for long periods to mitigate greenhouse gases. Biochar has been described as a soil conditioner and also decreased N2O and CH4 emission. Microbial activities play an important role in soil gas synthase, thus the mechanism of soil greenhouse gases reduction by addition of biochar, which remained unknown. The purpose of this study was to investigate the effects of biochar amendment on soil microbial growth, activity and community structure, as well as in the abundance of nosZ and norB genes. Four treatments have been designed, including control soil (C), control soil with biochar (CB), fertilization soil (F) and fertilization soil with biochar (FB). Soil microbial growth and activity were measured by plate counting and soil enzyme activities, while microbial community structure were analyzed by phospholipid fatty acids and denaturing gradient gel electrophoresis. Used PCR and electrophoresis to hemi-quantify the selected genes. The results showed that biochar application not only significant enhanced the growth and activity of microbes but also changed bacterial community structure after 60 days incubation. Analysis of N2O-related genes revealed that biocahr could increase nosZ gene abundant and decrease norB gene amount.