Preparation Of Tobacco Stems Biochar And Its Effects On Soil Carbon And Nitrogen Emission

Study on biochar has become a hot issue of current concern. Tobacco as an important economic crop, has a special economic value. Large amounts of tobacco waste(most of them are tobacco stems) will be produced in the tobacco production process, how to carry out effective resource utilization on the tobacco waste become more and more important. This experiment mainly studied the composition, structure and properties of tobacco stems biochar which produced under different pyrolysis temperature and different pre-treatment. And the effect of soil carbon and nitrogen emission with the factors of different amounts of tobacco stems biochar, single application and mix application with fertilizer. And then got the most suitable amount, effects on the fixed carbon and reducing discharge, while the growth of tobacco were also involved. The main results were as follows:1. The self-made pyrolysis device had a stronger operability in the process of preparation and at the range of 300℃~400℃, and the obtained tobacco stems bichar had a good appearance characteristic. As the pyrolysis temperature increased, tobacco stems biochar’s yield decreased, ash content increased, pH and specific surface area increased, aromatic functional groups and aliphatic C-H bond showed a gradual increasing trend, tobacco stems biochar’s pore aperture increased, the proportion of small holes decreased and medium holes increased, the content of organic matter and available phosphorus decreased gradually, available nitrogen’s content decreased after the first increased. Compared with segmented tobacco stems biochar, crushing tobacco stems biochar’s main nutrient content and pore size were lower, specific surface area was larger. tobacco stems biochar’s pore size mainly distributed in 1~40 ?m. Based on the above results, the composition, structure and properties of tobacco stems biochar under the condition of 400℃ and segment had a good performance.2. Adding tobacco stems biochar in soils could promote mineralization of SOC, but with the extension of culture time, the effect was gradually weakened. The most promoting was 1.0% treatment, followed by 0.5% treatment and 2.0% treatment. The 2.0% treatment could significantly reduce the accumulative mineralization rate of SOC compared with other treatments. There was no significant difference between 0.5%, 1.0% treatment and control yet. Adding tobacco stems biochar in soils could increase organic matter content of soil. Compared with control, the organic matter content of 0.5%, 1.0% and 2.0% treatment respectively increased 25.81%, 45.40% and 69.56%. Adding tobacco stems biochar in soils could promote the production and emission of CO2 in the early stage, but there was no significant promoting with the emission of CH4.3. Adding tobacco stems biochar in soils could decrease available nitrogen content in the early stage. And with the increase of biochar, the available nitrogen content showed a decreasing trend. Single applicating tobacco stems biochar was no significant influence with the nitrogen mineralization rate and nitrification rate. Mix applicating with fertilizer, the N2 O emission rate of 1.0% and 2.0% treatment were increased, there was no influence with the total amount of emission yet. Adding tobacco stems biochar in soils could promote the growth of tobacco in mid stage, and the most significant promotion was 1.0% treatment. Adding tobacco stems biochar in soils were beneficial for the accumulation of dry matter in later stage, and the most significant promotion was 1.0% treatment also.4. Adding tobacco stems biochar in soils had significant carbon sink effect. It could be an effective way for the fixed carbon and reducing discharge. The 2.0% treatment had the most significant promotion on carbon sink. But its promotion for the growth of tobacco was lower compared with the 1.0% treatment, and close to the 0.5% treatment. Also, considering the production costs and the labor costs in application of tobacco stems biochar, 1.0% treatment’s comprehensive effect was the best. So the 1.0% treatment could be the most suitable amount.