Effects of humic acid and its biodegradable film on continuous cropping soil environment and growth of Malus hupehensis seedlings
Under potted conditions,using the seedlings of Malus hupehensis as experimental materials,five treatments were set up,including continuous cropping soil,sterilized continuous cropping soil,continuous cropping soil with 1.5 g·kg-1 humic acid,continuous cropping soil with humic acid biodegradable film and continuous cropping soil with 1.5 g·kg-1 humic acid and humic acid biodegradable film.The effects of humic acid and its biodegradable film on the continuous cropping soil environment and the growth of Malus hupehensis seedlings were studied by measuring the biomass and root growth status of Malus hupehensis seedlings,the number of soil microorganisms,soil enzyme activity,soil nutrient content and other indicators.The results of the August sampling showed that compared to the control,the combined treatment of humic acid and humic acid biodegradable film significantly increased the height,ground diameter,fresh mass and dry mass of Malus hupehensis seedlings by 72.56%,58.50%,196.20%and 250.81%,respectively,and the root surface area,root volume,and root superoxide dismutase,peroxidase and catalase activities activities were increased by 74.93%,143.75%,63.40%,100.85%and 72.57%,respectively,compared with the continuous cropping soil.Humic acid and its biodegradable film could improve the soil environment,with the application of them,the bacteria in the soil increased significantly,the number of pathogenic fungus decreased significantly,and the bacteria/fungus ratio increased.Compared with the control,the number of bacteria and actinomycetes in continuous cropping soil with 1.5 g·kg-1 humic acid and humic acid biodegradable film increased by 115.79%and 135.14%,respectively,the number of fungus decreased by 87.25%,and the bacteria/fungus ratio improved by 16 times.The contents of soil organic matter and nutrients also improved.Moreover,the trend in September was consistent with that in August.In conclusion,the use of humic acid and its biodegradable film improved the soil environment and promoted the growth of Malus hupehensis seedlings while effectively reducing the continuous crop barrier of Malus hupehensis seedlings.
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