Both short- and long-term effects of fertilizers on crops and soils are often studied only in arid or paddy soils, whereas less is known about the long-term effects in paddy-upland rotations, particularly with multiple crops and frequent tillage in subtropical areas. Therefore, an 18-year field experiment was initialized to assess the effects of different types of fertilization (no fertilizer; chemical fertilizer (CF); and manure in combination with CF (MCF)) on yield and soil chemical and microbial properties in a crop rotation involving rice (Oryza sativaL., summer), rapeseed (Brassica campestrisL., winter), tobacco (Nicotiana tabacumL., the following summer), and hairy vetch (Vicia villosaRoth, the following winter). MCF caused higher yields of rapeseed grains and tobacco leaves than CF after 3 or 4 years of implementing the experiment, while rice yields varied little between MCF and CF, with one exception in 2011. Compared with the initial soil properties, providing soil with MCF increased organic matter (OM), while the opposite trend was found with CF. Higher microbial biomasses, enzyme activities, bacterial operational taxonomic units, and richness and diversity indexes of bacterial communities were found in soils receiving MCF, implying the improvement of soil microbial properties in the paddy-upland rotation system with multiple crops and frequent tillage. The experimental soils under varying fertilization were dominated by four bacterial phyla (Proteobacteria,Acidobacteria,Actinobacteria, and unclassified groups), which accounted for approximately 70% of the 16S rDNA sequences. Among the top 20 predominant bacteria, 14 were commonly found in all soil samples irrespective of which fertilizer treatment was implemented. Thus, the presence of those bacteria was stable in the soil and to some extent was influenced by fertilization. Most of them were facultative anaerobic bacteria, which can adapt to both anaerobic paddy soil and aerobic drylands. The dominant bacteria at various taxonomic levels found in soils might reflect multiple soil processes such as OM turnover, nutrient cycling, physical structure formation, and xenobiotic detoxification.

中文翻译：

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多作物和频繁耕作稻田-旱地轮作施肥的土壤质量和微生物学

肥料对作物和土壤的短期和长期影响通常只在干旱或稻田土壤中进行研究，而对稻田-旱地轮作的长期影响知之甚少，特别是在亚热带地区多种作物和频繁耕作的情况下. 因此，开始了一项为期 18 年的田间试验，以评估不同类型的施肥（不施肥、化肥 (CF) 和粪肥与 CF 结合使用 (MCF)）对作物产量和土壤化学和微生物特性的影响水稻轮作（水稻L., 夏季), 油菜 (油菜L.，冬天），烟草（普通烟草L.，接下来的夏天）和毛紫云英（紫花苜蓿罗斯，下一个冬天）。实施试验3、4年后，MCF使油菜籽粒和烟叶的产量高于CF，而MCF和CF的水稻产量差异不大，2011年有一个例外。与初始土壤性质相比，提供MCF的土壤增加了有机质 (OM)，而 CF 则相反。在接受MCF的土壤中发现了更高的微生物量、酶活性、细菌操作分类单元以及细菌群落的丰富度和多样性指数，这意味着在多作物和频繁耕作的水旱轮作系统中土壤微生物特性得到了改善。不同施肥条件下的试验土壤以四种细菌门为主（变形菌门,酸杆菌,放线菌, 和未分类的组), 约占 16S rDNA 序列的 70%。在排名前 20 位的优势细菌中，无论实施何种肥料处理，所有土壤样品中都普遍发现了 14 种。因此，这些细菌的存在在土壤中是稳定的，并且在一定程度上受到施肥的影响。多数为兼性厌氧菌，既能适应厌氧水稻土，又能适应好氧旱地。在土壤中发现的不同分类水平的优势细菌可能反映了多种土壤过程，例如 OM 周转、养分循环、物理结构形成和外源性解毒。