Bai Naling, Zhang Hanlin, Li Shuangxi, Zheng Xianqing, Zhang Juanqin, Zhang Haiyun, Zhou Sheng, Sun Huifeng, Lv Weiguang
Eco-environmental Protection Research Institute, Shanghai Academy of Agricultural Science, Shanghai, China.
Agricultural Environment and Farmland Conservation Experiment Station of Ministry Agriculture, Shanghai, China.
PeerJ. 2019 Jan 4;6:e6171. doi: 10.7717/peerj.6171. eCollection 2019.
Soil aggregation is fundamental for soil functioning and agricultural productivity. Aggregate formation depends on microbial activity influencing the production of exudates and hyphae, which in turn act as binding materials. Fungi are also important for improving soil quality and promoting plant growth in a symbiotic manner. There is a scarcity of findings comparing the long-term impacts of different yearly double-crop straw return modes (e.g., straw return to the field and straw-derived biochar return to the field) on soil aggregation and fungal community structure in rice-wheat rotation systems.
The effects of 6-year continuous straw and straw-derived biochar amendment on soil physicochemical properties and the fungal community were evaluated in an intensively managed crop rotation system (rice-wheat). Soil samples of different aggregates (macroaggregates, microaggregates, and silt clay) from four different fertilization regimes (control, CK; traditional inorganic fertilization, CF; straw returned to field, CS; straw-derived biochar addition, CB) were obtained, and Illumina MiSeq sequencing analysis of the fungal internal transcribed spacer gene was performed.
Compared to CF, CS and CB enhanced soil organic carbon, total nitrogen, and aggregation in 0-20 and 20-40 cm soil, with CB exhibiting a stronger effect. Additionally, agrowaste addition increased the mean weight diameter and the geometric diameter and decreased the fractal dimension ( < 0.05). Principal coordinates analysis indicated that fertilization management affected fungal community structure and aggregation distribution. In addition, CS increased fungal community richness and diversity, compared to CK, CB decreased these aspects. Ascomycota, unclassified_k_Fungi, and Basidiomycota were the dominant phyla in all soil samples. At the genus level, CB clearly increased fungi decomposing biosolids ( in macroaggregates in 0-20 cm soil and in macroaggregates in 20-40 cm soil); decreased pathogenic fungi ( in macroaggregates and in microaggregates in 0-20 cm soil) and CO-emission-related fungi ( in microaggregates and silt clay in 0-40 cm soil) ( < 0.05). Straw and biochar with inorganic fertilizer counteracted some of the adverse effects of the inorganic fertilizer with biochar showing better effects than straw.
土壤团聚对土壤功能和农业生产力至关重要。团聚体的形成依赖于微生物活动，微生物活动影响渗出物和菌丝的产生，而渗出物和菌丝又作为粘结材料。真菌对于以共生方式改善土壤质量和促进植物生长也很重要。关于不同年度双季作物秸秆还田模式（例如，秸秆还田和秸秆衍生生物炭还田）对稻麦轮作系统中土壤团聚和真菌群落结构的长期影响，相关研究结果较少。
在集约化管理的作物轮作系统（稻麦）中，评估了连续6年秸秆和秸秆衍生生物炭改良对土壤理化性质和真菌群落的影响。从四种不同施肥制度（对照，CK；传统无机施肥，CF；秸秆还田，CS；添加秸秆衍生生物炭，CB）获取不同团聚体（大团聚体、微团聚体和粉砂粘粒）的土壤样本，并对真菌内部转录间隔区基因进行Illumina MiSeq测序分析。
与CF相比，CS和CB提高了0-20厘米和20-40厘米土壤中的有机碳、全氮和团聚程度，CB的效果更强。此外，添加农业废弃物增加了平均重量直径和几何直径，并降低了分形维数（P<0.05）。主坐标分析表明施肥管理影响真菌群落结构和团聚体分布。此外，与CK相比，CS增加了真菌群落的丰富度和多样性，CB则降低了这些方面。子囊菌门、未分类的_k_真菌和担子菌门是所有土壤样本中的优势门。在属水平上，CB明显增加了分解生物固体的真菌（0-20厘米土壤大团聚体中的[具体数值1]和20-40厘米土壤大团聚体中的[具体数值2]）；减少了致病真菌（0-20厘米土壤大团聚体中的[具体数值3]和微团聚体中的[具体数值4]）和与CO排放相关的真菌（0-40厘米土壤微团聚体和粉砂粘粒中的[具体数值5]）（P<0.05）。秸秆和生物炭与无机肥料配合抵消了无机肥料的一些不利影响，生物炭的效果优于秸秆。
