Effects Of Fungus Residue Organic Fertilizer On Soil Fertility, Heavy Metal Accumulation Characteristics And Microbial Communit

In recent years,due to the rapid development of edible mushroom industry in Guizhou province,the production of edible mushroom residue as a by-product of this industry has increased year by year,and resource utilization of mushroom residue has received more and more attention.In this study,we used mushroom residue and other auxiliary materials to prepare mushroom residue organic fertilizer through composting and maturation.However,there is a lack of knowledge about the effects of mushroom residue organic fertilizer on soil physicochemical properties and biological environment,which restricts the promotion of edible mushroom industry.Meanwhile,the high background value of soil heavy metals in Guizhou,coupled with serious heavy metal pollution in farmland,the effect of organic fertilizer application on soil and crop heavy metals is also of concern.Therefore,in this paper,we selected spinach,which is easy to enrich heavy metals,and heavy metal contaminated soil,and set five application ratios(0,0.25%,0.5%,1%,1.5%)to carry out pot experiments on the application of mushroom residue organic fertilizer,and studied the characteristics of soil physicochemical properties,enzyme activity,microbial community,and changes of heavy metal content patterns of soil and spinach during its application,so as to provide the practical application of mushroom residue organic fertilizer.The main results of the study are as follows.(1)The mushroom residue organic fertilizer can effectively improve soil fertility and promote spinach growth.After the application of mushroom residue organic fertilizer,the average EC of the soil increased by 11.7%-98.7% compared with the control group,and improved the acidic soil to neutral,the average contents of AN,AP,AK and SOM increased by 8.55-78.69 mg/kg,2.43-22.78 mg/kg,7.18-22.44 mg/kg and 0.2%-1.9%;the average activities of soil UE and CAT increased by36.2%-116.4% and 17.8%-55.9%,but had no significant increase on ACP activity.The application of mushroom residue organic fertilizer promoted spinach growth,reduced spinach leaf yellowing,and increased spinach agronomic indexes by6.4%-84%.The effect of mushroom residue organic fertilizer on soil fertility and spinach growth promotion increased with the increase of application rate.(2)The mushroom residue organic fertilizer has passivation effect on soil Cd and Pb.The mushroom residue organic fertilizer can increase the EI of soil Cd and Pb,promote the transformation of Cd and Pb from the acid extractable and reducible states with high biological effectiveness to the oxidizable and residual states with low biological activity,and improve the stability of Cd and Pb in soil.The mushroom residue organic fertilizer can reduce the content of Cd and Pb in spinach,reduce the ability of spinach to enrich Cd and Pb,and have the effect of preventing the migration of Cd in spinach to edible part of spinach.(3)16S r DNA high-throughput sequencing technology revealed that the application of mushroom residue organic fertilizer significantly changed the structure of soil bacterial and fungal communities,and fungi were more affected by mushroom residue organic fertilizer.The results of β-diversity analysis showed that the variability of soil bacterial community increased with the dose of mushroom residue organic fertilizer application,while the variability of fungal community was not significantly related to the application dose.The application of mushroom residue organic fertilizer increased the relative abundance of soil eutrophic bacteria(Proteobacteria and Bacteroidetes),and decreased the relative abundance of soil nutrient-poor bacteria(Acidobacteria),optimizing the soil bacterial community.The relative abundance of Aspergillus increased,and the application of mushroom residue organic fertilizer at 1% or more decreased the abundance of soil Ascomycota and Basidiomycota.The mushroom residue organic fertilizer had no significant effect on soil bacterial functions,but the relative abundance of soil saprophytic nutrient fungi decreased and the relative abundance of pathogenic nutrient fungi increased with increasing application dose.Excessive application of mushroom residue organic fertilizer can increase the risk of soil disease.