Pedosphere: 土壤线虫多样性对农田有机肥施用量的响应
中国科学院东北地理与农业生态研究所农田有害生物控制学科组副研究员潘凤娟和黑土保护与利用学科组研究员韩晓增以农田生态系统不同有机肥施用量长期定位试验为研究平台，比较分析不施肥和化肥配施不同量有机肥土壤线虫群落组成和代谢足迹，阐明了有机肥施用量对土壤线虫群落结构和食物网功能的影响。相关成果发表于Pedosphere（IF=3.736）。
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It has been well documented that organic amendment affects soil nematode community structure. However, little is known about the effect of organic amendment amount on soil nematodes. To assess the effect of the amount of organic amendments on soil nematode community structure and metabolic activity, the community composition, abundance, and metabolic footprints of soil nematodes were determined in a long-term field experiment with various amounts of organic amendment in Northeast China. Fertilization treatments included an unfertilized control (CK), chemical fertilizer without manure amendment (OM0), manure applied at 7.5 Mg ha–1 plus chemical fertilizer (OM1), and manure applied at 22.5 Mg ha–1 plus chemical fertilizer (OM2). A total of 46 nematode genera were found. Treatments with the largest amount of organic amendment had the smallest number of plant parasite genera (5), but a largest number of dominant genera (7). Soil nematodes, bacterivores, and fungivores were the most abundant in OM2, followed by OM1, and the lowest in OM0 and CK. Organic amendment increased the enrichment index (EI), and the large amount of organic amendment increased the metabolic footprints of bacterivore (Baf) and fungivore (Fuf) and enrichment footprint (Ef). The relationships between Baf (or Fuf) and the increases in soil organic carbon (ΔSOC) and total nitrogen (ΔTN) were stronger than those of bacterivore (or fungivore) abundance with ΔSOC and ΔTN, except for the relationship between bacterivore abundance and ΔSOC. The EI and Ef were positively correlated with ΔSOC and ΔTN. These findings suggest that the amount of organic amendment affects soil nematode activity and function at entry levels in soil food web, and that metabolic footprints of soil nematodes may be better indicators than their abundances in assessing their relationships with soil nutrients.
土壤线虫是土壤中最丰富的多细胞动物之一，在土壤物质循环和能量流动中发挥重要作用，常作为土壤指示生物来评价外界扰动对土壤生物多样性的影响。在农田生态系统中，施用有机肥是提升土壤肥力、提高作物产量的一种有效方式。已有研究表明，施用有机肥影响土壤线虫的多样性，但关于有机肥施用量对土壤线虫群落结构和功能影响的研究较少。为此，中国科学院东北地理与农业生态研究所农田有害生物控制学科组副研究员潘凤娟和黑土保护与利用学科组研究员韩晓增以农田生态系统不同有机肥施用量长期定位试验为研究平台，比较分析不施肥和化肥配施不同量有机肥（0、7.5 t·hm-2和22.5 t·hm-2猪粪）土壤线虫群落组成和代谢足迹，阐明了有机肥施用量对土壤线虫群落结构和食物网功能的影响。
研究显示，在农田生态系统中，施用高量有机肥（22.5 t·hm-2猪粪）增加了优势线虫的数量，食细菌线虫和食真菌线虫的丰度随有机肥施用量的增加呈递增趋势。此外，有机肥的施用量还会影响土壤线虫食物网结构，线虫通路指数在5月和10月随有机肥施用量的增加呈降低趋势，而三个取样时期富集指数随有机肥施用量的增加均呈递增趋势（图1）。线性回归分析揭示了食细菌线虫和食真菌线虫的丰度及代谢足迹与土壤TOC和TN的增量为正相关关系（图2）。该研究表明，随着有机肥施用量增加，有机物细菌降解路径的比率增大，有机肥施用量主要影响处在食物网低营养级线虫的活性和功能；从土壤线虫群落结构和功能的角度来说，适量增加有机肥的施用量可以促进土壤食物网中的物质循环和能量流动。
图1 不同量有机肥处理下线虫食物网指数
图2 土壤线虫丰度和代谢足迹与土壤有机碳和总氮增量的关系
责任编辑：宋潇
校对和审核：张阳 王农