| 摘要: | 生物炭(biochar)是生物有機質材(農業廢棄物)在無氧或低氧環境中熱裂解後的固體產物，具有改善土壤理化性質與微生物活性、提高土壤有機碳儲存、延緩肥料養分釋放與減輕土壤污染等優點，研發利用生物炭降低化學肥料中氮素淋失有助於提高氮肥利用率和降低化肥施用量。本研究在缺氧狀態下，以熱裂解程序(350、500與800℃)製備蔗渣與稻殼生物炭，以蔗渣製成之生物炭可保留較高比例之碳質，分析生物炭物化特性，顯示裂解溫度為決定生物炭物化性質之重要關鍵，根據FT-IR圖譜顯示，800℃裂解之生物炭表面胺基減少，羧基增加，且具有較佳之微孔發展與比表面積，故對吸附酚之能力較佳；然對硝酸鹽吸附量較低，以低溫(350 ℃)裂解的生物炭有較佳之硝酸鹽吸附量，蔗渣生物炭的吸附量明顯較稻殼生物炭高。 以土壤管柱測定生物炭添加對土壤硝酸鹽淋失之影響，比較不同生物炭添加比例(10, 30 and 60 kg/ha)至陳厝寮系(Cce)及秀佑系(Si)土壤中，結果顯示於測試土壤中添加生物炭可減緩土壤硝酸鹽淋洗，裂解溫度越高及添加比例越多，硝酸鹽洗出量愈低。比較添加全化肥、全化肥與生物炭(2%)、1/2化肥與生物炭(2%)、生物炭(2%)四種處理進行青江菜栽培，栽培期間，量測植物生長狀態及採集土壤並分析土壤pH值、有機質及總凱氏氮，以探討生物炭對氮素保留及作物生長之影響。栽培收成後，分析植體葉片數、株高、乾重及其碳與氮含量。結果顯示，單獨添加800℃裂解之稻殼生物炭明顯提升土壤pH值，添加全化肥與800℃裂解之蔗渣生物炭對陳厝寮系土壤含氮量與青江菜之生長有提升作用，於秀佑系土壤施以1/2化肥與800℃裂解之稻殼生物炭(2%)對青江菜之株高與葉片數有促進效應，單獨施用生物炭使得植物之碳氮比明顯升高，顯示植物養分不均衡對植物生長不利。由上述結果可知，生物炭特性、土壤種類與配合肥料之施用方法等因子，均會影響生物炭對土壤環境改善與作物栽培之應用潛力。
Biochar was a solid byproduct derived from pyrolysis of biomass in low or absence of oxygen, high organic carbon content, highly capability of desorption, multiple-use materials.Biochar will be used to improve the physico-chemical characteristics of soil, activity of microorganism, extend the release rate of fertilizer nutrient, decline the demand of fertilizer and nutrient leaching, and prevent the pollution of soil. Due to the largest consume and low efficiency of chemical nitrogen fertilizer, evaluation the impacts of biochar application on nitrogen retention and availability of nitrogenous fertilizer in soil is a promising topic. In this study, rice husk and bagasse were used the candidate material, the raw materials were converted into biochar through pyrolysis in absence of oxygen at various temperature (350, 500 and 800℃). The results showed that higher carbon storage of biochar from pyrolysis of bagasse, pyrolysis temperature was the important factor to effect the properties of biochar. The FT-IR spectra of all biochars samples were in the range 4000-400 cm-1. It could be seen that increase of pyrolysis temperature would decrease the nitrate adsorption of biochar which was caused by decrease of amine group and increase of carboxyl group of surface functional group on biochars. Higher pyrolysis temperature would increase the micropore development, surface area and phenol adsorption of biochar. However, the most of biochars showed little capacity to absorb nitrate in the laboratory sorption experiments. The biochar made from bagasse and 350℃ could remove more nitrate from aqueous solution.The laboratory experiment was conducted to investigate the effects of biochar addition on dynamic changed of nitrate in soil column tests by adding various ratios (10, 30 and 60 kg/ha) of biochars. The results showed that leaching rate of nitrate was delayed by higher amendment ratio pf biochars and produced from higher pyrolysis temperature in Cce and Si soil. Various materials, pyrolysis condition, amendment ratio in soil were discussed and their effect on plant growth in soil environment were also investigated in this study. Comparison of four treatments (whole amendment of chemical fertilizer, whole amendment of chemical fertilizer and 2% biochar, 1/2 amendment of chemical fertilizer and 2% biochar, only 2% biochar) was taken in pot experiment of Chinese mustard (Brassica chinensis Linn). Soil pH, soil organic carbon content and total Kjeldahl-nitrogen content of soil were also concerned during the period of 35-d pot experiment. After 35-d pot experiment, numbers of leaves, plant height, dry weight, carbon and nitrogen content of plant were determined to imply the impacts of biochar amendment on nitrogen retention in soil and plant growth. Higher pyrolysis temperatures (800 ℃)-biochar amendment increased soil pH and organic carbon in Cce and Si soils significantly. The increase of total nitrogen content of soil and plant growth was observed with the treatment of whole amendment of chemical fertilizer and 2% 800℃ bagasse-biochar into Cce soil. The increase of plant height and numbers of leaves was observed with the treatment of 1/2 amendment of chemical fertilizer and 2% 800℃ rice husk-biochar into Si soil. Higher C/N ratio of plant shown in the treatment of only 2% biochar in both soils. Although limited to a short-term pot experiment, this research showed the application of biochar, soil types and combination of chemical fertilizer application to be promising of agronomic performance for improvement of soil environment and plant growth. |
