Preparation and Plant-growth Efficiency Assessment of Biochars

• Main Authors: Odette Marie Varela Milla, 歐蒂娣
• Other Authors: Wu-Jang, Huang
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/23229324041750065088

博士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 101 === 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.