| waste pyrolysis charring and biochar technology has become a very hot research frontier,has been in the environment,chemistry,agricultural resources and environment,materials science and other disciplines in research and application.First,this study has expounded that the degree of "hot" in the survey report about biochar technology in our country,setting the academic research direction in our country as the breakthrough point,the use of CNKI China journal full-text database and related statistics,combining keywords Citespace software visualization analysis method,systematically shows the general research situation of biochar technology in our country,the number of years,from the published literature,scientific research institutions,fund about biochar,and the elaboration to the biochar keywords of graduation thesis,subject distribution,meeting,newspaper reports,patents,the production application.Secondly,dealing with a variety of biomass waste by pyrolysis charring technology produced different biochar production,classifying raw material,choose the same charring equipment,1 h charring time in the middle of 450℃,different biochar received by the homologous raw material will determine physical and chemical properties,such as nutrient analysis,and planting Chinese cabbage pot adding mulitple biochar experiment,determination of the characteristics of Chinese cabbage,yield,quality,etc.,comparing the comprehensive screening.The research results are as follows:(1)according to the survey report,since 2011,the number of relevant published literatures has increased rapidly,but at present,the research on biochar in China is in the stage of rapid development;The research institution with the most publications is nanjing agricultural university,and the scholar with the most publications is professor Genxing Pan of nanjing agricultural university.China’s biochar research is mainly funded by national funds;The most published journal is journal of agricultural environmental science.The quantity of related degree thesis is mainly for master students.The subject with the largest amount of literature is environment science.At present,the research hotspot of biochar in China mainly focuses on soil aggregates,fertilizers based biochar,soil nutrients,tobacco planting soil,adsorption,preparation of modified biochar,soil remediation and other aspects.In general,the current research on biochar science and technology in China is mainly based on the agricultural field,but there is a trend of obvious expansion to the environmental field,and the pace is very fast.The restoration of soil pollution environment,improvement of soil quality and sustainable development of soil will also be an important trend in the future research on biochar in China.(2)The yield of 28 kinds of biochars obtained through pyrolysis charring was compared and analyzed:the average yield was 47.98%,the primary waste(52.22%),>secondary waste(50.73%)and>food processing waste(39.62%).Ash percentage of three types of biochar:secondary waste biochars 43.9%),>primary waste biochars(36.55%),>food processing waste biochars(23.71%).The pH of the 29 kinds of biochars were generally alkaline,in which the furfural residue and xylose residue were 3.83 and 5.98 in special cases,and the average pH of the 29 kinds of biochars were 8.91.The average of the three types of biochar EC is secondary waste biochars(3.22ms/cm),>food processing waste biochars(2.21ms/cm),>primary waste biochars(1.45ms/cm).In terms of cationic exchange capacity,a comprehensive comparison of 29 kinds of biochar was made,and the mean CEC of all kinds of biochar was expressed as follows:primary waste biochars(51.75cmol/kg),>secondary waste biochars(48.83cmol/kg),>food processing waste biochars(42.6cmol/kg).Three kinds of biochar in the organic carbon content indicators:food processing waste biochar(390.97 g/kg)>primary waste biochar(369.39 g/kg)>secondary waste biochar(206.58 g/kg),in addition to the feather powder and the biochar content of N elements were 13.06%and 9.74%respectively,raw materials and biochar is mainly composed of C,H,O,the three combined all more than 96%above;28 species biomass waste after 450℃ of pyrolysis charring,total nitrogen content change is the increase of the three largest coffee grounds,rice husk powder,slag,xylose,rose 71%,83%and 215%,respectively;The biggest increase of total phosphorus content was bone powder,mushroom residue and rabbit manure.In terms of total phosphorus content,except for the raw materials of silkworm sand and coconut residue,the content of other 26 kinds of waste materials increased significantly after being pyrolyzed.In terms of total nutrient content,except straw mushroom residue,coconut residue,furfural residue,cow dung,worm dung,feather powder residue and silkworm sand,all showed an increasing trend,and most of them showed an obvious increase.28 kinds of waste material after 450℃ pyrolysis charring 1 h,nitrogen recovery of different waste raw material range is wide,and there is no as before by three kinds of biomass have significant differences,28 kinds of raw material after thermal pyrolysis charring average nitrogen recovery rate is 45.98%;In terms of nutrient recovery rate of phosphorus element,total phosphorus element;In terms of the recovery rate of potassium,potassium is relatively stable,and the average recovery rate of potassium is higher than that of nitrogen and phosphorus,reaching 68.65%.(3)Chinese cabbage in the pot experiment,adding different biochars on the plant height and biomass of Chinese cabbage root has significant effect,such as comparing CK treatment,on the part of the root system of underground biomass c significantly effect on promoting the gain,compared with the CK average growth of 57%,the secondary waste biochar(83%)>native waste biochar(44%)>food processing waste biochar(43%).In terms of root crown ratio,the overall increase rate was 19%.Compared with CK treatment(0.0161%),the root crown ratio in the first batch of pot experiment was significantly increased(0.025%on average),while that in the second batch was not so.Compared with CK treatment(0.0821%),it showed a downward trend(0.0716%on average).Compared with CK blank control,the first batch of Chinese cabbage potted plants with different biochar increased their yield by an average of 26%.The plants with the highest yield were those treated with animal biochar,followed by those treated with tobacco stalk powder biochar and those treated with straw mushroom residue biochar,with an increase of 88%,78%and 69%,respectively.Compared with CK treatment,the average yield of the second batch of Chinese cabbage pot was increased by 157%,among which the Chinese cabbage with the largest yield increase was 21.66g treated with bone powder biochar,and the yield increased by 311%,followed by Chinese cabbage with silkworm sand biochar and sheep manure biochar.The overall yield increase was 86%,from the perspective of three types of biochar:secondary waste biochar(141%),>food processing waste biochar(59%),>primary waste biochar(58%).The soil properties of biomass biochar were improved,and the slightly acidic soil was generally improved.The EC and CEC of potted soil were generally improved after the planting of Chinese cabbage.Compared with CK,potted soil was improved by 35.59%,42.11,10.86%and 51.71%respectively,which was more conducive to the growth of plants.From the perspective of the three types of biochars,in terms of the percentage of EC increase,the primary waste biochar(35%),>secondary waste biochar(18%),>food processing waste biochar(19%);In terms of SOC,the improvement of SOC by three types of biochar is significant:food processing waste biochar(56%),>secondary waste biochar(48%),and>primary waste biochar(37%).Quality of Chinese cabbage:in terms of nitrate content in two batches of Chinese cabbage potted plants,compared with CK treatment,the average decrease of 29 species treated with biochar was 8.83%.In terms of vitamin C content,compared with CK blank control,the average increase rate reached 60%,and the increase was very obvious.In terms of soluble sugar content of Chinese cabbage,the overall difference was not significant,with a decrease of 0.75%.In terms of soluble protein content,the average increase rate was 24.22%,and the overall increase trend was obvious.Comparative evaluation was made from the perspective of the average percentage increment in quality of the three types of biochar treatment compared with CK blank control:in terms of reducing the nitrate content of Chinese cabbage,secondary waste biochar(15%),>primary waste biochar(9%),>food processing waste biochar(6%);In terms of improving VC content of Chinese cabbage,secondary biological waste biochar(67%),>primary waste biochar(57.8%),>food processing waste biochar(57.2%);In terms of soluble sugar,sub-biological waste biochar(6%),>food processing waste biochar(3%),>primary waste biochar(-12%);In terms of soluble protein content,the primary waste biochar(29%)was>secondary waste biochar(28%)was>food processing waste biochar(14%).Finally,compared with CK blank control,the 29 kinds of biochar treatments were mainly based on the positive two-way synergistic effect of biochar on the quality and yield of Chinese cabbage,and 4 types of biochar were selected according to the characteristics.In the structure of biochar,the increase of output is strongly positively correlated with the total pore volume and SF total micropore volume,and moderately positively correlated with the yield and specific area of biochar,and weakly correlated or not correlated with other properties. |
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