黄土高原旱地麦田26年免耕覆盖对土壤肥力及原核微生物群落多样性的影响

为明确黄土高原旱作麦田长期保护性耕作对土壤肥力和土壤原核微生物的效应，以位于山西省临汾市实施保护性耕作26年的小麦田为试验基地，采用Illumina Hiseq 2500高通量测序等手段，开展了不同耕作措施免耕覆盖（NTS）、深松免耕覆盖（SNTS）和传统耕作（TT1）]对土壤理化性质和土壤原核微生物多样性的影响分析。研究结果表明：1）NTS和SNTS处理比TT1处理显著提高了土壤全氮、碱解氮、速效磷及速效钾的含量，降低了土壤pH，提高了土壤贮水能力和水分含量，降低了0~10 cm土层的土壤容重，但提高了10~20 cm土层的土壤容重；同时，SNTS处理显著增加了土壤的有机质含量。2）Illumina Hiseq高通量16S rRNA基因V4区测序结果表明：NTS和SNTS处理比TT1处理显著降低了绿弯菌门的相对丰度；NTS比SNTS处理显著降低了土壤中疣微菌门和绿弯菌门的相对丰度；NTS处理显著增加了土壤原核微生物群落的多样性，但未显著改变原核微生物群落的丰度；SNTS对原核微生物群落的多样性和丰富度均未有显著改变；NTS处理的显著性差异物种（Biomarker）高于其他2个处理；其他原核微生物门的相对丰度，在3个处理间尚未有明显差异。3）聚类分析可见：NTS和SNTS处理与TT1处理的微生物群落结构差异较大；NTS处理与SNTS处理间的微生物群落结构差异较小。4）CCA分析可知：土壤pH、有机质、速效氮、速效磷、速效钾含量对土壤原核微生物群落遗传多样性的变化起着重要作用；与TT1处理相比，NTS和SNTS处理在一定程度上改变了土壤原核微生物群落结构，但仍存在结构的相似性。综上所述，长期进行NTS和SNTS处理对黄土高原旱地麦田土壤微生物多样性、丰富度以及土壤肥力因子等的正效作用明显。

Effect of long-term no-tillage with stubble on soil fertility and diversity of prokaryotic microbiome in dryland wheat soils on the Loess Plateau, China

In dryland regions, conservation tillage has the advantages of reducing soil erosion, maintaining soil structure, improving soil physical and chemical properties, and promoting microbial reproduction, compared with traditional farming methods. Up to now, the effect of long-term conservation tillage on soil prokaryotic microbial community has not been adequately reported for the China''s Loess Plateau region. To understand the effects of long-term conservation tillage on soil prokaryotic microbial community diversity and soil fertility in dryland wheat fields on the Loess Plateau, the Illumina Hiseq 2500 high-throughput sequencing and physicochemical test methods were used to analyze the effects of different tillage measures on soil physical and chemical properties and the diversity of soil prokaryotic microbial community in the wheat fields in Linfen City, Shanxi Province. Tillage measures adopted in the study area for 26 years included no-tillage with stubble (NTS), no-tillage with stubble after subsoiling (SNTS) and traditional tillage (TT1). The results showed that:1) while soil contents of total nitrogen, available nitrogen, available phosphorus, available potassium, and soil water storage capacity and water content under NTS and SNTS treatments were significantly higher than those under TT1, soil pH under NTS and SNTS was lower than that under TT1. NTS and SNTS treatments reduced soil bulk density in the 0-10 cm soil layer, but increased it in 10-20 cm soil layer compared with TT1 treatment. Meanwhile, SNTS treatment significantly increased soil organic matter content. 2) The results of the Illumina Hiseq high-throughput 16S rRNA gene sequencing in area V4 indicated that:SNTS treatment significantly reduced the relative abundance of Chloroflexi, compared with TT1 treatment. NTS treatment significantly reduced the relative abundance of Verrucomicrobia and Chloroflexi, compared with SNTS treatment. NTS treatment significantly increased the diversity of soil prokaryote community, but not significantly changed the abundance of prokaryote community. SNTS treatment not significantly changed the diversity and richness of prokaryote community. Biomarkers under NTS treatment were higher than under other treatments. The relative abundance of other prokaryotes at the phylum division was not significantly different among three treatments. 3) UPGMA analysis showed that prokaryote community structures of NTS and SNTS were significantly different from those of TT1, and the differences between NTS and SNTS were small. 4) CCA analysis showed that soil pH, contents of organic matter, available nitrogen, available phosphorus and available potassium were important for changes in genetic diversity of soil prokaryote communities. Although NTS and SNTS treatments could change soil prokaryotic microbiome structure greatly, there was still structural similarity among the soil prokaryotic microbiomes among three treatments. To sum up, long-term conservation tillage had obvious positive effects on soil microbial diversity, richness and soil fertility in dryland wheat fields on the Loess Plateau.