Effects Of Different Fertilizer Application Measures On Soil Characteristics And Tobacco Growth And Development

At present,the soil quality of tobacco-growing soils is degraded due to unreasonable application of chemical fertilizers and long-term continuous cropping.The application of decomposed straw,sesame cake fertilizer and biochar can not only reduce the waste of agricultural wastes,but also become an important strategy for the development of green ecological agriculture.It can also fix carbon and fertilize soil,improve crop yield and quality?and promote the sustainable production capacity of soil.Therefore,the pot experiment of Zhongyan 100 was carried out in 2017 and 2018 for two consecutive years.Six fertilization treatments were set up:no fertilization,single application of nitrogen fertilizer,combined application of nitrogen,phosphorus and potassium fertilizer,application of decomposed straw,sesame cake fertilizer and biochar respectively to explore the effects of different fertilization measures on soil characteristics and growth and development of tobacco plants.The results are as follows:1.The application of chemical fertilizer decreased soil pH and increased application of decomposed straw had a tendency to further reduce soil pH.Heavy application of chemical fertilizers or organic materials can increase the content of available nitrogen,available phosphorus and available potassium in soil.Biochar(T6)combined with chemical fertilizers can improve the content of total phosphorus and total potassium in soil best.Compared with nitrogen,phosphorus and potassium combined application,the content of total phosphorus in soil with biochar(T6)increased by 12.15%90 days after transplanting in 2018.2.Input of organic materials significantly increased the activities of invertase,urease,catalase and the number of bacteria,fungi and actinomycetes in soil,among which the effect of biochar treatment on catalase was the most significant.The number of fungi and actinomycetes in soil treated with decomposed straw was higher than that of other treatments.Compared with the soil before transplanting,the diversity of soil bacteria and fungi increased significantly during tobacco harvest.There was no significant difference in microbial diversity among different fertilization treatments.Proteobacteria,Bacteroidetes and Firmicutes were the dominant phylum in all treatments.At generic level,fertilization significantly reduced the relative abundance of Aeromonas,but increased the relative abundance of Georgfuchsia,Sphingobium and Nitrospira.The relative abundance of Sphingobium in the treatment of N,P and K combined with biochar was higher than that in other treatments.At the gate level,the relative abundance of Ascomycota increased while that of Basidiomycota decreased at harvest compared with that before transplanting.The relative abundance of Basidiomycota treated with N,P and K combined with decomposed straw was higher than that of other treatments.At generic level,the relative abundance of Cortinarius,Paratritirachium and Calulina decreased at tobacco harvest.Adding biochar increased the relative abundance of Chaetomium.3.Compared with no fertilizer and chemical fertilizer,the content of soil organic carbon components and soil respiration rate increased with the addition of organic materials.Among the three treatments with organic materials,the TOC content of soil treated with biochar was higher than that of other treatments 60 days after transplantation in 2017 and 2018,but the cumulative emission of CO2 was the lowest,and the TOC content of straw treatment was only lower than that of biochar treatment as a whole.Reasonably,the cumulative emission of CO2 is the highest.Except 60 days after transplanting in 2017,the DOC content of nitrogen fertilizer treatment was higher than that of non-fertilizer treatment,and the DOC content of nitrogen,phosphorus and potassium fertilizer treatment was lower than that of non-fertilizer treatment in 2017.In 2017(45 and 60 days after transplanting)and 2018,the ROC content of fertilizer treatment alone was higher than that of non-fertilizer treatment.Two-year experimental results showed that there was a close relationship between TOC,DOC and MBC,and there was a significant positive correlation between TOC and soil respiration rate.4.In 2017,SO42-,HCO3-,Na+and Ca2+were the main components of soluble salt in all treatments.In 2018,SO42-,HCO3-,K+and Ca2+were the main components of soluble salt in all treatments.Fertilizer application increased the total salt content as a whole,and the combined application of N,P and K fertilizers mainly increased the contents of SO42-,HCO3-,and K+.Adding organic material treatment reduced the total salt content.Organic materials also reduced the content of Ca2+in soil as a whole,and the effect on Na+content varied with time.The treatment of decomposed straw increased the content of Cl-but decreased SO42-,and the treatment of biochar increased the content of K+.5.Compared with no fertilization,fertilization significantly increased plant height,stem circumference and maximum leaf area.Compared with the combined application of N,P and K fertilizers,the plant height and maximum leaf area of tobacco treated with sesame cake fertilizer increased by 12%and 36%respectively 90 days after transplantation in 2018.The application of organic materials increased the yield and output value of Flue-cured tobacco,as well as the contents of total sugar,reducing sugar and nicotine in tobacco leaves.Biochar treatment increased K+content in flue-cured tobacco leaves.The net photosynthetic rate and mineral element absorption of tobacco were also significantly increased by applying organic fertilizer.