| Gleyed paddy fields are impregnated with water for a long time,resulting in poor permeability,severe soil anoxia,microbial low activity,and massive accumulation of reducing substances,thus poisoning the crop roots.The nutrient and organic matter content of these soils is high,but their effectiveness is low due to the low temperature and reducing environment.Therefore,gleyed paddy fields have great potential to be transformed into high-yielding fields.Based on water management and improvement of soil condition by application of soil improver,we used gleyed rice fields as the target subject for this study in order to investigate the effects of water management,application of soil conditioners as well as the cooperative regulation of the content of soil reducing substances,enzyme activity and microbial community structure in gleyed rice fields,providing a theoretical basis for the improvement of gleyed rice fields.The main results are as follows:(1)Soil redox potential showed an overall downward trend and then upward trend during the fertility period of early and late rice in the field,and was negatively correlated with the content of reducing substances.The effect found to be better.(2)At the maturity stage of late rice in the field,peroxidase activity was significantly increased in soil samples from T5～T8 containing open furrow treatments compared to the control,with the highest peroxidase activity(17.256 U/g)in T5 trenching treatment,followed by T6 trenching with sodium humate treatment.All the treatments enhanced soil acid phosphatase activity except T3 monopoly crop and T4 monopoly crop with sodium humate treatment.(3)At field late rice maturity,T3 increased the relative abundance of Proteobacte ria in soil,which was significantly increased by 6.05% compared with CK.The relati ve abundance of Chloroflexi was in the order of T2(sodium humate)>T4(trenching)>T3(ridge)>T1(control),and the application of sodium humate significantly increased the relative abundance of Chloroflexi by 25.32% compared with CK.T4 increased th e relative abundance of Acidobacteria.The relative abundance of Nitrospirae phylum(T1 >T2 >T4 >T3)was in the order of T1 >T2 >T4 >T3.All treatments reduced the relative abundance of Nitrospirae,with T2,T4 and T3 decreasing by 11.22%,13.27% and 22.45%,compared with CK.Ditching reduced bacterial alpha diversity,and b eta diversity analysis revealed that different engineering measures had more significant effects on microbial community structure.(4)At the tillering stage of potted rice,all treatments reduced the total amount of reducing substances,active reducing substances,and T2 alternating wet and dry treatment,T13 alternating wet as well as dry treatment with calcium peroxide,sodium humate and biochar had the best reduction effect on the attenuation of the substances.From the tillering stage to the maturity stage,T8 with high concentration of biochar started to gradually reduce the reducing substances,and T13 at the maturity stage had the best effect on the reduction of total reducing substances and active reducing substances,followed by T8 and T2.T13 and T1 treatments had the lowest ferrous and manganese contents at the maturity stage.The previous period T3,T4 low and high concentration of calcium peroxide treatment redox potential was high,while it started to decrease at late growth stage.The trend of dissolved oxygen concentration was basically the same as the redox potential,and the highest dissolved oxygen concentration was found in T2 alternating wet and dry treatment.(5)Soil enzyme activity was increased by T2 and T13 containing alternating wet and dry treatments at maturity in potted rice,with significant effects except for catalase.The application of high concentration of biochar increased soil enzyme activity,but the effect of low concentration of biochar was not significant.Compared with the use of soil conditioner,wet and dry alternation was more effective in increasing soil enzyme activity in submerged rice fields,and there was no significant difference between T2 wet and dry alternate and T13 wet and dry alternate with soil Improver.(6)The highest relative abundance of Chloroflexi,Proteobacteria,and Actinobacteria were the dominant bacterial groups in the soil of potted rice at maturity.Application of sodium humate and biochar increased bacterial alpha diversity,while dry and wet alternation suppressed bacterial alpha diversity.Based on the beta diversity and cluster analysis,it could be found that the dry-wet alternation was the most crucial factor affecting the microbial community structure. |
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