In recent years, improved paddy crop varieties, advanced tools and technologies have resulted in a huge quantity of crop residues (CRs) production. Hence, appropriate sustainable management of the paddy CRs produced annually is needed. In this study, a field experiment was conducted to evaluate the impact of rice husk biochar (RHB) amendments on soil physico-chemical characteristics, methanotrophs diversity, and functional pmoA genes numbers in paddy soil. ThepmoA gene (27 kDa) encodes the β-subunit of the particulate methane monooxygenase (pMMO), an enzyme responsible for methane oxidation found in most of the methanotrophs. A marked variation in methanotrophs diversity, functional pmoA genes abundance, and physico-chemical parameters in paddy soil have been noted across the given amendments. The RHB significantly improves soil physico-chemical status and enhances methanotrophs community structure and number of pmoA gene numbers in paddy soils. The various soil physico-chemical parameters were improved due to RHB + microbial inoculant treatments. Maximum rice grain yield (5.91 ± 0.07 t ha⁻¹) and methanotrophic functional pmoA gene numbers (57.25 ± 0.88 × 10⁷ g⁻¹ paddy soil) were found in the RHB + microbial inoculant treated plot compared to untreated (control) plot. The predominant methanotrophic bacteria identified by the denaturing gradient gel electrophoresis (DGGE) in RHB treated paddy soils were Methylovulum and Methylobacter members of the Methylococcaceae family. Consequently, the methanotrophs community study based on DGGE analysis shows that RHB could be a beneficial amendment to increase the methanotrophic community composition in paddy soils. Overall, the results suggest that the RHB amendment could markedly enhance soil conditions and methanotrophs abundance via regulating soil physico-chemical properties in nutrient-deprived and degraded paddy agriculture soils.

中文翻译：

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稻谷作物残留物的可持续管理：对甲烷氧化菌多样性的影响和土壤健康恢复的价值

近年来，水稻作物品种的改良、先进的工具和技术导致了大量的作物残留物 (CRs) 生产。因此，需要对每年生产的水稻 CR 进行适当的可持续管理。在本研究中，进行了田间试验以评估稻壳生物炭 (RHB) 改良剂对稻田土壤理化特性、甲烷氧化菌多样性和功能性pmoA基因数量的影响。所述pmoA基因（27 kDa）的编码微粒甲烷单加氧酶（的β亚单位单加氧酶），负责甲烷氧化的酶在大多数的甲烷营养的发现。甲烷氧化菌多样性、功能性pmoA 的显着变化水稻土壤中的基因丰度和物理化学参数已经在给定的修正中得到了记录。RHB显着改善了土壤理化状态，增强了水稻土中甲烷氧化菌群落结构和pmoA基因数量。由于RHB+微生物菌剂处理，各种土壤理化参数得到改善。最大水稻产量 (5.91 ± 0.07 t ha ^-1 ) 和甲烷营养功能pmoA基因数 (57.25 ± 0.88 × 10 ⁷  g ^-1与未处理（对照）地块相比，在 RHB + 微生物接种剂处理的地块中发现了稻田土壤）。通过变性梯度凝胶电泳 (DGGE) 在 RHB 处理的稻田土壤中鉴定的主要甲烷氧化菌是 Methylococaceae 家族的Methylovulum和Methylobacter成员。因此，基于 DGGE 分析的甲烷氧化菌群落研究表明，RHB 可能是增加稻田甲烷氧化菌群落组成的有益改良剂。总体而言，结果表明，RHB 改良剂可以通过调节营养缺乏和退化的水稻农业土壤中的土壤理化性质，显着改善土壤条件和甲烷氧化菌丰度。