田菁生物炭添加對土壤養分與溫室氣體釋放的影響

現有的研究顯示施加生物炭會影響土壤中碳及氮的礦化過程,因而能改變溫室氣體的釋放;也發現施加生物炭能有效提昇土壤的物理、化學性質,進而提高農業生產的效率。本研究探討 1. 未炭化的綠肥作物和其不同炭化溫度之生物炭結構上的差異;2. 將上述材料加入土壤後,這些差異如何影響土壤二氧化碳、氧化亞氮及甲烷的釋放;3. 上述材料如何影響土壤中碳、氮的礦化,以及磷及其他養分的釋放;以及 4. 檢驗施加上述材料對作物生物量及達有龍施用效果的影響。本研究使用田菁作為材料,以 200°C、300°C、400°C 及 500°C 的溫度將其炭化,分析田菁及其生物炭化學結構的差異,並將上述材料加入土壤進行孵育試驗,過程中收集所釋放之土壤溫室氣體以及淋洗溶液進一步分析; 另外也以上述材料進行作物盆栽試驗及達有龍吸附試驗。實驗發現添加生物炭使土壤二氧化碳及氧化亞氮累積釋放量顯著減少,並使甲烷被土壤吸收;越高溫炭化的生物炭在土壤中碳礦化的速度越慢,氮的礦化量也越少,甚至造成固定化作用;生物炭能釋出磷、鉀、鈣、鎂到土壤中,釋放量與炭化溫度亦成正比;施加生物炭可能降低作物生物量,並降低達有龍的效用。本研究歸納出, 炭化能使生物質內的碳氮轉變為不易分解的形式,因而減少其礦化及釋放;將田菁炭化可以達成減緩溫室氣體釋放的目標,然而當炭化溫度升高,田菁作為綠肥作物的功能隨之減少。

關鍵字

生物炭；化學結構；溫室氣體；碳礦化；氮礦化；土壤養分

並列摘要

Studies have shown that amending biochar to soil is able to change the processes of C and N mineralization, therefore affect the emission of soil greenhouse gases; it can also improve the physical and chemical properties of soil, therefore enhance the agricultural performance. The aims of this study are to understand 1. How do charring temperature affect the chemical structure of biochar, and what are the structural differences between raw material and biochar; 2. How do these structural differences affect the emission of soil carbon dioxide, nitrous oxide and methane after the biochar and raw material are amended into soil; 3. How do these amendments affect the mineralization of C and N, and the release of P and other nutrients; and 4. The effect of these amendments on crop biomass and Diuron performance. First of all, we charred Sesbania sesban at 200°C, 300°C, 400°C, and 500°C, then analyzed the chemical structure of these materials. Second, we combined these materials with soil to carry out incubation experiments, and collected emitted greenhouse gases and leached solution during incubation. Last, we combined these materials and soil to carry out crop pot experiment and experiment of Diuron sorption. The results show that the emission of carbon dioxide and nitrous oxide are significantly lower in the biochar amended treatment, while methane is uptaked by soil. The mineralization of C and N are slower when biochar charred at higher temperature were added to soil, and the addition even led to soil N immobilization. Biochar may release P, K, Ca and Mg into the soil, and the released amount is proportional to the charring temperature. Biochar amendment may decrease the crop biomass and the performance of Diuron. We conclude that charring changes the structure of C and N in raw material into a more stable state and slows down their mineralization processes; charring Sesbania sesban into biochar leads to reduced emission of soil greenhouse gases, but as the charring temperature rises, Sesbania sesban gradually loses its function as green manure.

並列關鍵字

biochar ； chemical structure ； greenhouse gas ； carbon mineralization ； nitrogen mineralization ； soil nutrients

參考文獻

Aguilar-Chavez, A., Diaz-Rojas, M., Cardenas-Aquino, M.d.R., Dendooven, L., Luna-Guido, M., 2012. Greenhouse gas emissions from a wastewater sludge- amended soil cultivated with wheat (Triticum spp. L.) as affected by different application rates of charcoal. Soil Biology and Biochemistry 52, 90-95.

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Bruun, E.W., Ambus, P., Egsgaard, H., Hauggaard-Nielsen, H., 2012. Effects of slow and fast pyrolysis biochar on soil C and N turnover dynamics. Soil Biology and Biochemistry 46, 73-79.

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Chan, K.Y., Van Zwieten, L., Meszaros, I., Downie, a., Joseph, S., 2007. Agronomic values of greenwaste biochar as a soil amendment. Australian Journal of Soil Research 45, 629-629.

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田菁生物炭添加對土壤養分與溫室氣體釋放的影響

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