生物炭之製備及其植生應用效益之評估

Preparation and Plant-growth Efficiency Assessment of Biochars

歐蒂娣(Odette Marie Varela Milla)

指導教授 ： 黃武章

國立屏東科技大學/國際學院/熱帶農業暨國際合作系/博士(2013年)

https://doi.org/10.6346/NPUST.2013.00093

摘要

生物碳是由有機物質(如農業廢棄物或是植體等生質物)所製備的碳材料，其可用來增加土壤的固碳能力並改善其養分含量與水分的滯留能力。生物碳亦可使保持土壤中的營養成分與增加陽離子交換能力、降低土壤酸度、改善土壤結構，減少非二氧化碳溫室氣體的釋放。因此生物碳的生產與應用有著良好的成果且在固碳效應改善土壤健康事具有相當大的潛力，但目前生物碳的分類研究較少有系統性的歸納。因此本研究之目的在於利用有機廢棄物製備生物碳、分析其概念與起源，並調查其在農業種植中的關鍵性。同時研究生物碳的生產與作物生長之效應評估，或是與其他工業固體廢棄物(如底渣)混合之潛在用途分析。本研究主要的發現如下：
以底渣混合乾燥之玉米生質物進行多酚的萃取的研究中發現未添加肥料時，其所多酚含量為5~25mg/L；當添加化學肥料時會造成多酚含量增加到44~55 mg/L，且呈現抑制作物的生長。此外由研究結果可知生物碳有助於底渣中所含多酚的降解。以竹材與稻殼混合所製備之生物碳與垃圾焚化底渣混合後進行作物之生長評估上發現，其混合物對玉米的生長初期具有一定的影響力。且結果顯示，以400oC製備之稻殼生物碳與底渣混合並分別添加與未添加肥料時具有最佳之作物發芽率與植體重，其作物發芽率可達100 %，且在過程中無中金屬鉛與銅的溶出。

以稻殼生物碳進行空心菜之生長測試結果顯示，當生物碳添加入土壤中所栽培之空心菜的根部、葉寬與植株重均較未添加生物碳之試驗組作物明顯增加。且空心菜的莖部尺寸與(保水力/坋粒含量)比值成正比；根部尺寸與(土壤有機物含量/有機碳)比值成正比。且發現以稻殼製備生物碳的過程中具有較高含量的矽元素，且具有溶解性。其在土壤改質的應用上可扮演由土壤傳輸至植體水分與微量元素的螯合作用並提升作物之生長速率。但其含量具有一臨界值，當稻殼生物炭中的矽含量超過20 ％時則會造成作物發芽率的抑制作用。
以竹材製備生物碳為較佳的選擇，其有助於相關產業的轉型與獲利且對任何的生態系統具有較低的危害性。此部分的研究主要是以240oC、300oC、600oC與700oC進行竹材製備生物碳之潛力與作物之生長評估。其結果發以240oC與300oC竹生物碳有助於小麥種子的發芽率提升50 %；而600oC與700oC則會造成種子發芽率的抑制(均施以100 %之生物碳環境下)。

關鍵字

農業廢棄物 ； 生物碳 ； 熱裂解 ； 生質物 ； 碳封存

並列摘要

Biochar is charcoal made from organic matters such as plant biomass and agricultural wastes that can be used to increase soil ability to sequester carbon and simultaneously improve its nutrient contents and water retention. Biochar can aid in nutrient retention and cation exchange capacity, decreasing soil acidity, decreased uptake of soil toxins, improving soil structure, nutrient use efficiency, water-holding capacity, and decreased release of non-CO2 greenhouse gases. There is great potential for biochar production and application to have positive outcomes through carbon sequestration, and improved soil health. Few researches in biochar classifications have been done.
The aims of this study is to generate biochars from organic wastes, to analyze their concept and origins, to investigate their key roles on agriculture planting, to study the effect of production process, on the plant germination rate and their potential uses with other industrial solid wastes, such as bottom ash. The major founds in this thesis are as follow:

Extraction of polyphenols from a municipal solid waste incineration (MSWI) bottom ash mixed matrix and Zea mays L. dry biomass. Polyphenol content was shown to increase when fertilizer was applied, presenting inhibition to plant growth, root yield and plant biomass dry weight. After fertilizer application, the polyphenol content increased between 45-55 mg/L. Without the fertilizer, the polyphenol content was 5-25 mg/L. In addition, the used bottom ash (BA) enhanced biochar degradation; this process could be achieved through our results.
Results from studies made on the mixture of bamboo biochar and rice husk biochar with municipal solid waste incineration bottom ash let us conclude that the mixture of these components has a positive effect on the development and early growth of corn (Zea mays L.). The treatment that showed the best results in this test without a concern about the leaching of heavy metals lead (Pb) and cooper (Cu) was rice husk. This treatment was pyrolized at 400ºC and combined with Pingtung MSWI bottom ash, with and without additions of fertilizer; the treatments showed the best results in germination (100%) and plant weight.
With regards of the results, detailing the growth of water spinach, they showed that the application of rice husk biochar improves biomass production. The wood biochar added to soil increased the plant weight of water spinach by increasing the root size and leaf width, whereas rice husk biochar added to soil increased plant weight by increasing the stem size and leaf length of the water spinach. In addition, the stem size of water spinach was proportional to the ratio of water-holding capacity to silt content in soil; whereas the root size of water spinach was proportional to the organic matter/organic carbon ratio of soil.
Moreover, rice husk biochar process produces high silicon content, and its application in soil induces dissolvable silicon in soil that plays a chelator role in transporting water and trace elements from the soil matrix to the plant. Rice husk biochar application affects significantly the corn seeds germination and improves the plants growth rate due to the high silicon (Si) content found. In addition, the silicon was found to have a critical threshold when its content in the rice husk biochar is higher than 20%, which is a sufficient level to be harmful for corn seed germination.
The use of bamboo is a smart option for those industries that want to transform biochar into a profit without harming any ecosystem. The main objectives of this study are to investigate the potential capability of bamboo biochar to affect germination and growth of edible crops. In conclusion, the four temperatures (240ºC, 300ºC, 600ºC and 700ºC) of bamboo biochars used in this study generally increased wheat seed germination at rates of application of 50% for 240ºC and 300ºC biochars; while 600ºC and 700ºC biochars tended to inhibit germination at the highest rate of application (100%) under the bioassay conditions.
This study demonstrated the potential of biochar as an amendment of clayey soils. Our findings suggest that an application rate of 10 t ha-1 should not be exceeded when applying biochar on these soils.

並列關鍵字

agriculture waste ； biochar ； pyrolysis ； biomass ； carbon sequestration

參考文獻

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