| In order to reduce the harm of excessive chemical fertilizer to the environment and agricultural production,and achieve the sustainable development of agriculture,the research and application of new fertilizers,such as microbial fertilizer,humic acid fertilizer and water-soluble fertilizer,have become an important research interests for agricultural researchers.Humic acid fertilizer has a significant promotion and improvement effect on plant growth and soil.Woody peat is one of the main mineral raw materials for humic acid extraction and production.Mineral source humic acid usually needs to be activated before it can be used in agriculture to achieve the maximum utilization of humic acid resources.Activation of humic acid by functional microorganisms is a simpler,cleaner and cheaper method compared with physical and chemical activation.Biologically activated humic acid and its fertilizer have outstanding biological activity.In this study,solid fermentation of Bacillus velezensis SQR9was performed by woody peat.Humic acid in woody peat was activated during the multiplication of strain SQR9.Relevant indexes were measured to evaluate the activation effect,and a woody peat humic acid bio fertilizer was prepared by optimizing the fermentation formula.In addition,an active three-acid liquid water-soluble fertilizer was developed by mix the activated woody peat humic acid with amino acids andγ-PGA.At last,the application methods and dosage of the two kinds of fertilizers and their promoting effect on vegetable crops were explored through pot experiment.(1)By optimizing the supplemental amount of rice bran,soybean meal and inoculation amount of strain SQR9,the results showed that when the inoculation amount of strain SQR9was 5%,and the supplemental amount of soybean meal and rice bran were 5%,the content of Bacillus in solid fermentation product increased compared with the initial inoculation amount,and reached about 6×10~7 CFU/g.The humic acid content increased from value of21%to 28%,and it increased by about 33.0%compared with raw materials.After fermentation,the content of DOC increased from 5 mg/L to 67 mg/L.In addition,the Fourier transform infrared spectroscopy results of humic acid showed that the intensity and area of the characteristic absorption peaks of partial functional groups increased with the fermentation process,indicating that the number of functional groups on the structure of humic acid increased through activation.(2)The plant growth promotion effect of woody peat humic acid bio-organic fertilizer was studied through pot experiment of pakchoi and cucumber.The results showed that compared with no fertilization control(CK),the application of chemical fertilizer and woody peat humic acid bio-fertilizer significantly improved the plant height,leaf growth characters and plant biomass of the two vegetable crops,while the application of woody peat raw material had no significant growth-promoting effect.Among them,The aboveground fresh weight of pakchoi treated by reduced 50%chemical fertilizer with woody peat humic acid bio-fertilizer(T1),1%of woody peat humic acid bio-fertilizer(T3)and 2%of woody peat humic acid bio-fertilizer(T4)increased by 716.2%,129.6%and 231%respectively than CK,the underground fresh weight increased by 169%,65.5%and 89.7%,respectively,the plant height were 102.7%,38.9%and 58.9%respectively;Compared with CK,the fresh weight of cucumber(growing to 90 days)treated by T3 and T4 increased by 72.1%and91.5%,the dry weight increased by 70.6%and 103.9%,the plant height increased by 88.7%and 107.5%,respectively.Compared with the woody peat raw material(T2),the aboveground fresh weight of pakchoi treated by T3 and T4 increased by 126.4%and 226.4%,respectively,and the underground fresh weight increased by 45.4%and 66.7%,respectively.The plant growth promotion effect gradually improved by the increase of application amount.There was no significant difference between T1 treatment and CF treatment in promoting the growth of pakchoi,indicating that woody peat humic acid bio-organic fertilizer could replace part of the chemical fertilizer.(3)Results of green house experiment by using active three-acid liquid water-soluble fertilizer showed that water-soluble fertilizer could moderately improve the growth of cucumber leaves and shoots,among which water-soluble fertilizer diluted 100 times by root soil fertigation had the best promoting effect.Compared with the water control,the chlorophyll SPAD value,maximum leaf area,plant height and fresh weight of shoot and root were significantly increased by 13.0%,58.0%,64.0%,57.7%and 35.6%,respectively.In summary,in consideration of the content of SQR9 strain,humic acid content,changes in soluble carbon and the FTIR of humic acid,the solid state fermentation of Bacillus velezensis SQR9 by woody peat achieve to the biological activation of humic acid in woody peat,and the pot experiment showed that woody peat humic acid bio-fertilizer and a liquid soluble fertilizer containing humic acid,amino acid andγ-PGA had great growth promoting effect on vegetable crops.This study aims to provide theoretical guidance and technical support for the efficient utilization of humic acid resources,and the development and application of humic acid new fertilizer. |
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