| In this paper,in view of the serious degradation of black soil quality in northeastern meadows and the unbalance of soil microflora,organic fertilizer and biochar were applied respectively in two methods of deep tillage and shallow tillage for a two-year location test,with the purpose of determining the effects of organic manure and biochar on soil enzyme activity and bacterial biodiversity under different tillage methods;Redundancy analysis was used to confirm the influence of fertility factors on the accumulation of dominant bacteria in bacterial diversity;All these furnish rational exploitation and protection of arable land with theoretical basis and technical guidance.Based on the full amount of straw returning to the field,this experiment was treated with two main treatments,i.e.the deep tillage?D:tillage depth of 30cm?and the shallow tillage?S:tillage depth of 15cm?,under which organic fertilizer?M?and biochar?B?were set as secondary treatments.Formula fertilizer?N-P2O5-K2O 13-16-10?of 600 kg/ha was applied to each treatment.Soil samples of different depths?0-20cm,20-40cm,40-60cm?were taken to study the effects of fertilization on soil enzyme and bacterial biodiversity in different depth soil layers under different tillage conditions.The main results are as follows:Compared with the deep tillage control treatment?DCK?,the shallow tillage control treatment?SCK?could significantly improve the activities of cellulase,fibrinolytic enzyme and FDA hydrolase in surface soil?0-20cm?,where,however,the activities of soil dehydrogenase and polyphenol oxidaseis were principally affected by DCK treatment and remarkably higher than that of SCK treatment.In deep soil?20-60 cm?,DCK treatment could increase the activity of each enzyme that is notably higher than SCK treatment.However,the activity of fibrinase was slightly different in the 20-40 cm soil layer,and its enzyme activity was DCK<SCK treatment.The significant difference of the effects of biochar and organic fertilizer on the enzyme activities in different soil layers was observed under different tillage conditions,but for different fertilization treatments,the activity of each enzyme had a consistent tendency in all soil layers.Application of organic fertilizer under different tillage conditions could increase the activity of every enzyme in the topsoil and is significantly higher than that of biochar treatment.On the contrary,the effect of fertilization treatment on each enzyme activity in deep soil?20-60 cm?showed that it was biochar treatment>organic fertilizer application.According to the Venn graph analysis,the bacterial biodiversity in soil of DCK was prominently higher than that of SCK.The significant analysis?confidence interval was 95%?showed that when the tillage and fertilization were used as single factor analysis,the effect on bacterial diversity in soil was not notable,but the fertilization treatment under different tillage modes had a contrary effect bacterial diversity,especially the changes of bacterial diversity in soil treated with organic fertilizer.Proteobacteria and Actinobacteria accounted respectively for26.15%,29.87%and 25.4%,21.28%of the relative abundance of DM and SM treatment soils.The species diversity analysis illuminated that DB treatment could significantly increase the bacterial biodiversity in the soil with a higher distribution similarity of Proteobacteria and Actinobacteria.Through RDA?redundancy analysis?,it was found DCK was obviously influenced by fertility factors,in which soil bacterial diversity was positively correlated with available nitrogen in soil,and negatively correlated with fertility factor available phosphorus,available potassium and pH.In terms of the correlation between the relative abundance and enzyme activity of five dominant bacteria in soil,the relative abundance of Proteobacteria in soil had a positively correlation with soil dehydrogenase and cellulase activity?P?0.05?;The relative abundance of Bacteroidetes was significantly positively correlated with cellulase activity. |
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