不同沼液施用年限土壤养分含量和微生物群落结构差异

【目的】研究连续施用沼液替代全部化肥对耕层土壤物理、化学以及生物性质的影响，为沼液安全施用提供依据。【方法】沼液全量替代化肥田间试验在浙江湖州进行，以推荐化肥施用量为对照，并设置施用等氮量的沼液1年、2年和3年处理，共4个处理。每季水稻施用沼液2次，分别在6月和9月，每次施用量约300t/hm²。水稻收获后采集植株和土壤样品，分析水稻产量、氮磷钾含量和蛋白质含量，以及0—20 cm土层土壤理化性状，采用Miseq高通量测序技术分析了土壤微生物群落结构。【结果】施用沼液1年、2年和3年的稻米平均产量分别为9669、9765、9823 kg/hm²，均显著高于化肥对照(7800 kg/hm²)，年度之间产量差异不显著。施用沼液显著增加了稻米中的蛋白质和氮、磷、钾含量，对直连淀粉含量无显著影响。施用沼液改善了土壤养分状况，与CK相比，沼液施用2年后降低了土壤pH，但施用3年后，对pH无明显影响；速效磷含量增加显著，但施用年限间无显著差异；有效钾逐年显著提高；沼液施用2年和3年后显著降低了铵态氮含量而硝态氮含量则显著增加；全氮和...

Variation of nutrient content and microbial community in soils under different application years of biogas slurry

  【Objectives】  We investigated the in the physical, chemical and biological properties of the topsoil with different biogas slurry application years.   【Methods】  The field experiment of replacing chemical fertilizer with biogas slurry was conducted in Huzhou, Zhejiang Province. The control plots were applied with only chemical fertilizer, while the treatment plots were applied with only biogas slurry for 1yr, 2 yr and 3yr. All the four treatments were applied with the same amount of N each year. Biogas slurry was applied two times during each rice season, in June and September of each year, and each application amount was about 300 t/hm2. Plant and soil samples were collected after rice harvest every year. Rice yields and relevant physicochemical properties were investigated, and resident microbial community was analyzed through Miseq high-throughput sequencing.  【Results】  The rice yields of 1, 2 and 3 years of biogas slurry application were 9670 kg/hm2, 9765 kg/hm2 and 9823 kg/hm2. The rice yields of the three application treatments were similar, but all significantly higher than the chemical fertilizer control (7800 kg/hm2). Besides, the biogas slurry application increased the content of protein and NPK, not affected the amylose content in grains. Compared with CK, biogas slurry application improved soil chemical properties significantly. 2yr treatment was recorded lower pH but 3yr was recorded similar pH with CK. All the 1yr, 2yr and 3yr treatment were recorded similar but higher available P, total N and organic matter content. The NH₄+-N and NO₃--N content were significantly decreased in 2yr and 3yr treatment than in 1yr treatment. Available K and the activities of C-, N- and P-acquiring enzymes kept increasing with the continue application of biogas slurry. The results of soil microbial community analysis showed that the longer the biogas slurry was applied, the higher the microbial markers abundance (most of which were nitrogen cycle-related microorganisms) would be. In addition, short-term (1 year or 2 years in this study) biogas slurry application increased microbial community abundance and phylogenetic diversity, while α diversity recovered back to the initial status (P>0.05) after long-term biogas slurry application. Besides, β diversity of microbial community also showed a significant recovering tendency.   【Conclusions】  Biogas slurry application could effectively increase the yield and nutrition quality of rice, without decreasing the taste of rice. Biogas slurry application could improve and maintain a high and stable soil organic matter, total N and available P, accumulate available K, but decrease inorganic N contents. Short-term (1 year or 2 years in this study) application of biogas slurry will increase the soil microbial diversity, however, the soil microbial diversity may decrease gradually with the increasing application period.