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研究生:李弘達
研究生(外文):Li, Hung-Ta
論文名稱:水田及旱田土壤中脫氮作用之影響因子
論文名稱(外文):The affecting factors of denitrification in paddy and upland soils
指導教授:林良平林良平引用關係
指導教授(外文):Lin Liang-Ping
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:農業化學系
學門:農業科學學門
學類:農業化學類
論文種類:學術論文
論文出版年:1997
畢業學年度:85
語文別:中文
論文頁數:85
中文關鍵詞:脫氮作用脫氮菌水田旱田影響因子
外文關鍵詞:denitrificationdenitrifierpaddy soilsupland soilsaffecting factors
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氧化亞氮 ( N2O ) 佔總溫室氣體的 6 %,雖然所佔的比例不大,但
是由於其吸收紅外線輻射能之能力為等量二氧化碳之 250 倍,且能殘留
長達 150 年,加上現今正以每年 0.25 % 的速率增加,因此氧化亞氮在
溫室效應中佔有不容忽視之地位。土壤脫氮作用為氧化亞氮釋出的主要來
源之一,本實驗乃採取台灣大學農業試驗場及桃園農業改良場之水田、輪
作旱田於不同作物生長時期土壤以 MPN 法估算土壤中脫氮微生物的數目
,用來評估土壤中的脫氮族群分布。並取台灣大學農業試驗場之水田及旱
田土壤進行實驗室培育實驗,探討溫度、含水量、有效碳及硝酸鹽對脫氮
作用的影響。以 MPN 法估算脫氮菌數得知:台灣大學農業試驗場水田於
八十五年第一期平均脫氮菌數最高,八十四年第二期次之,八十五年第二
期最低;桃園農業改良場水田於八十四年第二期高於八十五年第一期。台
大農場和桃園農改場皆於蔬菜園之平均菌數高於旱田,可得知土壤中之脫
氮菌數與作物種類有關。有機肥料的施加亦會增加土壤中之脫氮菌數。本
研究中發現台大農場土壤脫氮酵素活性分析最適基質濃度為:葡萄糖用量
以每克乾土 5 *mol ,而硝酸態氮為每克乾土 10 *mol。環境因子的探討
:台大農場水田土壤於 30℃及35℃培養下釋放出高量之氧化亞氮,而旱
田土壤於 30℃培養下氧化亞氮釋放量最高。而水分含量在無氧情況下對
脫氮作用影響並不顯著。脫氮作用進行時,所需之硝酸態氮濃度有一定之
限制,過低時 ( 1mM ) 則因脫氮作用缺乏基質而無法進行;過高時 ( 10
mM ) 則脫氮作用會受抑制。可利用碳在低濃度 ( 1,5 mM ) 硝酸鹽培育
下,對脫氮作用有增進作用。關鍵字:脫氮作用、脫氮菌、水田、輪作旱


Nitrous oxide (N2O) was one of greenhouse gases.The amount
of N2O is occupied six percentage of greenhouse gases in
atmosphere.The absorption in infrared radialization by N2O was
higher than CO2. Therefore, the effect of global warming of N2O
was very important.The production of gaseous nitrogen (N2O and
N2) by microbial reduction of nitrogenous oxides (NO3- and NO2-)
is known as biological denitrification.In this study, we
utilized the most-probable-number (MPN) method for the
enumeration of denitrifying bacteria to assess the
denitrification potential. The soils were taken from two sites
at Agricultural Experimental Station, College of Agriculture,
National Taiwan University (AESNTU) and Taoyuan District
Agricultural Improvement Station (TDAIS). Results from MPN
method from two selected soils indicated that the enumeration of
denitrifying bacteria of paddy soils from AESNTU during the
first crop season of 1996 were the highest, that during the
second crop season of 1996 were the lowest. The enumeration of
denitrifying bacteriaof paddy and dryland soils from TDAIS
during the second crop season of 1995 were more than that during
the first crop season of 1996. Both of the enumeration of
denitrifying bacteria of vegetable field soils from AESNTU and
TDAIS were more than that of upland field soils. In this result,
the number of denitrifiers in soil would be changed by various
crops. Besides,the addition of organic fertilizers would
increase the number of denitrifiers in soils.In this study, we
found the optimum concentration of available carbon and nitrate
to analysis of denitrification enzyme activity in paddy and
upland soils from AESNTU. The optimum concentration of available
carbon was 5*10-6 mol glucose g-1 dry soil, and the optimum
concentration ofnitrate was 1*10-5 mol nitrate g-1 dry soil.
Denitrification in soil was affected by many environmental
factors.The emission of N2O from AESNTU paddy soils was the
highest during 30 and 35℃, and that from AESNTU upland soils
was the highest during 30℃. The effect of water content in the
study of emission of nitrous oxide was not notable. Nitrate and
available carbon were important to denitrification. However,
high nitrate concentrations may affect N2O production. Key words
: denitrification, denitrifier, paddy soils, upland soils

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