Abstract Soil degradation is often accompanied with the decrease of soil organic matter and soil fertility, and the direct addition of organic carbon and nitrogen could be the good method to accelerate the restoration of soil system of degraded grassland. The effects of the addition of biochar and nitrogen on soil properties and microorganisms in the 0-20 cm soil depth of degraded alpine grassland were evaluated. The treatments consisted of three different levels of biochar (1 kg m−2, 2 kg m−2, and 4 kg m−2) and nitrogen (5 g m−2, 10 g m−2, 15 g m−2). The addition of biochar and nitrogen increased soil organic carbon, total nitrogen, available phosphorus, water content (SWC), urease, phosphatase，and microbial biomass. The relative content of arbuscular mycorrhizal fungi, 18:1w9c fungi, actinomycetes, gram-negative and gram-positive bacteria increased, however, 18:2w6,9c fungi, anaerobic bacteria and methanotrophic bacteria decreased. Under the effect of biochar and nitrogen addition, most of soil physicochemical properties showed significant correlation in the 0-20 cm soil layer. The correlation between microbial community and soil properties mainly occurred in the 0–10 cm soil layer. The community of fungi, actinomycetes, gram-negative and Gram-positive bacteria showed significant relationship with soil urease, phosphatase, and available phosphorus (P 0.30). Arbuscular mycorrhizal fungi showed strong positive correlation with pH, NH4+, and SWC. These results indicated that the addition of biochar and nitrogen quickly improved soil nutrient and microbial community of degraded alpine grassland and could be used for the remediation of degraded alpine grassland.

中文翻译：

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有机碳和氮的添加加速青藏高原退化高寒草地土壤系统的恢复

摘要 土壤退化往往伴随着土壤有机质和土壤肥力的下降，直接添加有机碳和氮是加速退化草地土壤系统恢复的好方法。评价了生物炭和氮的添加对退化高寒草地0-20 cm土层土壤性质和微生物的影响。处理包括三种不同水平的生物炭（1 kg m-2、2 kg m-2 和 4 kg m-2）和氮（5 g m-2、10 g m-2、15 g m-2）。生物炭和氮的添加增加了土壤有机碳、全氮、有效磷、含水量（SWC）、尿素酶、磷酸酶和微生物生物量。丛枝菌根真菌、18:1w9c真菌、放线菌、革兰氏阴性菌和革兰氏阳性菌增加，但18:2w6,9c真菌、厌氧菌和甲烷氧化菌减少。在生物炭和氮添加的作用下，0-20 cm土层的大部分土壤理化性质表现出显着的相关性。微生物群落与土壤性质的相关性主要发生在0~10 cm土层。真菌、放线菌、革兰氏阴性菌和革兰氏阳性菌群落与土壤脲酶、磷酸酶和有效磷显着相关（P<0.30）。丛枝菌根真菌与pH、NH4+和SWC呈强正相关。