Production And Fertilizer Efficiency Of Organic Fertilizer Made From Vinasse And Effect Of Biochar Made From Vinasse

China is a large producer and consumer of liquor in the world.The annual output of liquor is about 13 million tons and Luzhou flavor liquor（Baijiu）accounts for more than 70%of all liquor in China.The production of 1 ton of Baijiu consumes 2.5-3.0 tons of sorghum.At the same time,3 tons of vinasse and 48 tons of wastewater were produced.There are 93 million vinasse in Baijiu processing and a large amount of sludge in brewery wastewater treatment（hereafter,it simply referred to as sludge）,which are urgent to harmlessly treat and utilize as a resource.Due to low pH（4.0-4.5）and over 70%of rice husks that contain cellulose,cellulose,silica,and a small amount of proteins,vinasse has low nutritional values and poor palatability and can not be used as animal food.There are secondary by-product residues if vinasse is used as raw materials for producing biogass and extracting feed proteins,leading to incomplete harmless treatment.As a result,these methods are difficult to be popularized in practices.Landfill and incineration are the main ways to treat the vinasse and sludge,which pollute the environment and are costly.There are no reports on the integration of the vinasse and sludge harmless treatment.It is worth noting that both vinasse and sludge are rich in organic matter and plant nutrients,which could be potentially used as an organic fertilizer.Also,Luzhou is the main producing areas of Baijiu,where the soils for growing sorghum,a main raw material,are deeply weathered,deficient in organic matter,strongly leached,and have low pH values.It is urgent to improve these soils in sorghum cultivation.In addition,biochar is used to improve acid soil,increasing soil organic carbon is one of the hot spots of current research,and there are few reports on reducing vinasse to prepare biochar for acid soil.The main aims of the present experiments were to（i）develop a technique for the production of organic fertilizer（OF）using vinasse and sludge as the raw materials,（ii）realize the influence of the OF and biochar made from the vinasse,and（iii）understand the changes in microbial communities and the metabolisms of carbon and nitrogen（N）by metagenomes.The results may provide some scientific references for the harmless treatment and resource utilization of solid wastes in Baijiu processing.The following are the main results:（Ⅰ）Temperature changes in the mixture of the vinasse,sludge,and microbial agent were divided into the temperature raising,high temperature,and cooling period stages.During the composting period,the material moisture continually decreased,whereas N,phosphorus（P）,potassium（K）,and humic acid gradually increased.The color of the composting material changed from yellow-brown to brown,black-brown,or black.The OF was successfully produced from the mixture of sludge and vinasses（1:2 in mass）approximately 40 days after the addition of microbial agent.All indexes of OF met the national standard NY/525-2012.（Ⅱ）Compared with only CF,OF plus chemical fertilizer（CF）at the proportion of a1:1 organic:inorganic N ratio increased sorghum yield by 12.55%,grain N by 36.70%,plant P uptake by 22.22%,and plant K absorption by 29.20%.The available N and P,and activities of urease and dehydrogenase were also significantly increased in the soil with OF plus CF.The use of OF in proper combination CF may thus be beneficial to the achievement of high sorghum yield,the improvement of plant nutrition,and the increase in sorghum enzyme activity in the soil.（Ⅲ）The field experiment showed the use of OF in combination with CF at a 1:1organic:inorganic N ratio achieved the highest wheat yield.OF increased the wheat yield by 17.78%compared with commercial organic fertilizer（COF）,which suggested the better efficiency of OF than the COF.The application of OF plus less CF had higher total N,Na OH-hydrolyzed N,NH₄⁺-N,and enzyme activities（including invertase,urease,and catalase）in the soil than only CF and COF.（Ⅳ）The application of organic fertilizer,biochar and their combination can significantly increased the field yield and 1000 grain weight of sorghum;the combination of biochar made from the vinasse and organic fertilizer improved the quality of sorghum（the content of soluble protein and starch increased）,and soil nutrients,microbial biomass and enzyme activity can also be increased.Although the response of single cropping sorghum to single application of organic fertilizer made from the vinasse was slightly better than other treatments,the long-term effect of biochar needs to be further verified by long-term experiments.（Ⅴ）Soil is the main factor determining the microbial community structure,which was also varied with biochar addition to a certain extent.The numbers of microbial DNA sequences and bases in the soil were increased by the addition of biochar made from the vinasse,indicating more microbes present in the soil.The biochar influenced the abundances of microbial genes depending on the microbial species.The proper application of biochar significantly increased the gene abundances of unclassified bacteria,bacteria,archaea,viruses,and eukaryotes in the soil.Similarly,the soils that received adequate biochar had larger numbers of genes encoding the enzymes relevant to C and N metabolisms.More pathways of C and N metabolisms were found in the soil with biochar.