| As an important cash crop,excessive application of chemical fertilizers has become one of the imminent problems limiting tobacco development in some areas due to shortage of arable land resources and driven by economic interests.At present,domestic and foreign experiments on organic fertilizers instead of chemical fertilizers are mainly on rice,corn,wheat and other crops,but there is a lack of systematic theoretical and long-term positioning experiments based on tobacco.For this reason,this study selected the main cultivar Cuibi No.1in Sanming area as the test object,and used organic fertilizers such as livestock manure,rice straw and biochar to partially replace chemical fertilizers in a long-term positioning test to explore their effects on soil properties,growth and quality of flue-cured tobacco.The main results were as follows:1.Effects of different organic fertilizers replacing chemical fertilizers on soil p H,total carbon and nutrients of flue-cured tobacco:during the peak season,soil p H increased significantly in each organic fertilizer treatment compared to chemical fertilizer treatment,and pig manure treatment could significantly increase total carbon content in soil.According to the long-term localization analysis,soil p H content was significantly increased in chemical fertilizer,chicken manure,pig manure,cow manure,rice straw,charred pig manure,and charred rice straw treatments compared to the original soil(CK)in 2016,with the cow manure treatment being the most suitable for increasing soil p H.soil total carbon content was significantly higher in each treatment compared to CK,with the pig manure and charred pig manure treatments being the most effective in increasing soil total nitrogen content.During the peak season,the alkaline nitrogen content was significantly higher under chicken manure,pig manure,cow manure,rice straw,charred pig manure and charred rice straw treatments compared to the chemical fertilizer treatments,with the highest soil alkaline nitrogen content after pig manure treatment.Soil effective phosphorus content was significantly increased under organic fertilizer chicken manure,pig manure,rice straw and charred pig manure treatments,with the highest soil effective phosphorus content under pig manure treatment and significantly higher than under chicken manure,rice straw and charred pig manure treatments.Soil fast-acting potassium content was significantly higher in chicken manure and pig manure treatments than in chemical fertilizer treatments.Under long-term positioning test conditions,with the original soil(CK)in 2016 as the control,pig manure could significantly increase the total soil nitrogen,phosphorus and potassium content of fast-acting nitrogen,phosphorus and potassium.2.The effect of different organic fertilizers instead of chemical fertilizers on the inter-root soil enzyme activity of flue-cured tobacco during the peak season: compared with conventional application of chemical fertilizers,pig manure organic fertilizer treatment significantly increased urease activity;charred pig manure treatment significantly increased sucrase activity;polyphenol oxidase activity decreased under all treatments,with the lowest enzyme activity under charred rice straw treatment;the acidic protease activity was significantly increased under the treatment of cow manure and chicken manure,while the acidic protease activity was significantly decreased under the treatment of rice straw and its charred treatment;charred pig manure treatment significantly increased acid phosphatase enzyme activity;pig manure treatment significantly The pig manure treatment significantly increased the cellulase activity in the soil by 23.92% compared with the conventional application of chemical fertilizers.3.Effects of different organic fertilizer treatments on inter-root soil microorganisms during the peak season of flue-cured tobacco: there were3191 bacterial OTUs and 302 fungal OTUs in the soil under different organic fertilizer treatments,and the application of different organic fertilizers,except chicken manure,significantly increased bacterial diversity,which in turn had a certain effect on the quality of flue-cured tobacco.The organic fertilizer treatment did not change the ecological community structure of the original soil microorganisms.The functional prediction of bacteria showed that the application of chemical fertilizer improved the function of bacterial metabolism of carbon,the application of charred rice straw and rice straw promoted the function of bacterial carbon and nitrogen metabolism,and the application of cow manure,charred pig manure and pig manure treatment could increase the reproductive repair function of bacteria.4.Effects of different organic fertilizers instead of chemical fertilizers on yield and quality of flue-cured tobacco: Compared with chemical fertilizer treatments,pig manure treatment could significantly increase the root,stem,leaf and total fresh weight of tobacco plants.Cow manure treatment significantly increased the root,stem and total fresh weight of tobacco plants;while cow manure treatment significantly reduced the fresh weight of tobacco leaves by 13.12%.Compared to chemical fertilizer treatments,cow manure and pig manure treatments significantly increased the dry weight of tobacco plant roots,stems and leaves,with the greatest increase in dry weight of pig manure treatment.While rice straw fertilizer significantly decreased the root dry weight compared to chemical fertilizer treatment.Charred pig manure significantly increased the dry weight of flue-cured tobacco leaves,but charred organic fertilizer application had no significant effect on the total dry weight of the tobacco plants.Compared to chemical fertilizer treatments,organic fertilizer treatments resulted in significant increases in nicotine,total sugar,and total chloride content in flue-cured tobacco,increases in reducing sugar and decreases in total potassium content in flue-cured tobacco treated with chicken manure and pig manure,and decreases in reducing sugar and increases in total potassium content in flue-cured tobacco treated with cow manure and rice straw.Charred organic fertilizer showed a significant decrease in nicotine content and a significant increase in total and reducing sugars content compared to organic fertilizer treatments.Compared with the chemical fertilizer treatment,the straw treatment increased the yield and production value of top grade tobacco but decreased the yield and production value of medium grade tobacco.Taken together,conventional organic fertilizer and charred organic fertilizer treatments had no significant effect on the total value of tobacco.In conclusion,pig manure organic fertilizer treatment could effectively improve soil physicochemical properties and microbial community structure,while promoting excellent flue-cured tobacco agronomic traits.In the field trial,there was no significant difference in the total value of flue-cured tobacco production between the treatments. |
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