Effects Of Biochar And Reductive Soil Disinfestation On Soil Properties And Greenhouse Gas Emissions In Degraded Vegetable Soil

Over-fertilization and consecutive monoculture in facility vegetable cultivation lead to soil deterioration,which seriously affect the sustainable development of vegetable industry.In this experiment,the soil of pepper for 5 years in Fuqing area of Fujian Province was studied,rice straw and its biochar?BC,rice straw pyrolysed at 450°C?were used as remediation materials to investigate the change of soil some properties,greenhouse gas emissions and soil microbial community structure during remediation of facility vegetable field using reductive soil disinfestation?RSD?technique.1.Compared with untreated soil?CK?,the soil DOC,pH,the electrical conductivity?EC?,total carbon?TC?,total nitrogen?TN?and C/N ratio of BC addition increased significantly at the end of 21 days incubation?P<0.05?,but the contents of soil NH₄⁺and soil NO₃^-did not change significantly.The results also showed that the soil DOC,pH,TC and C/N ratio with RSD treatments was significantly higher than that of CK treatment,but soil NO₃^-and soil EC was significantly lower than that in the CK treatment after 21days incubation?P<0.05?,and soil NO₃^-content was effectively eliminated within 3 days.The application of BC in RSD remediation significantly increased soil pH,EC,TC and C/N ratio?P<0.05?,but it had no significant effect on the content of soil NH₄⁺and NO₃^-.Adding BC and straw significantly changed the basic properties of soil.2.After incubation,Total phospholipids fatty acids?PLFAs?in BC addition was slightly higher than that in CK treatment,but did not reach a significant level,and had no significant effect on soil microbial community composition.Total PLFAs increased by66%-112%after RSD remediation,but BC addition in RSD remediation had no significant effect on PLFAs.After RSD remediation,the change of Gram-negative?GN?was not significant compared with CK treatment,while the abundance of Gram-positive bacteria?GP?was significantly increased.Adding BC in RSD remediation increased the abundance of Gram-positive?GP?bacteria in soil,but did not reach a significant level.After RSD remediation,the abundance of arbuscular mycorrhizal fungi?AMF?,actinomycetes?ACT?and fungi?FUNGI?decreased significantly,but didn't decreaced further when BC was added in RSD treatments.RSD treatments increased the ratio of Gram-positive to negative bacteria?GP/GN?,decreased the ratio of fungi to bacteria?F/B?,and significantly changed the microbial community structure;compared with RSD treatment,there was no significant effect on soil microbial community structure,while adding BC in RSD remediation.Therefore,in this experiment,RSD remediation significantly changed soil microbial community structure,while BC addition had no significant effect on soil microbial community structure.3.Compared with the CK treatment,BC addition increased the emission of N₂O,but had no significant effect on CO₂ emission under aerobic condition.In the process of RSD remediation,a large amount of N₂O and CO₂ were produced,and CO₂ emission increased with the increase of rice straw addition.The addition of BC in RSD significantly inhibited N₂O emission of 16.4%-46.8%,and the effect of inhibition was more significant in higher BC addition treatments.However,excessive BC addition would cause a small amount of CO₂ emission.