氮肥减施与配施有机肥对冬小麦土壤线虫群落结构的影响

土壤线虫是指示土壤健康的典型生物之一,为了揭示氮肥减施对土壤健康的影响,以冬小麦土壤为对象,研究了氮肥减施和配施有机肥对拔节期冬小麦土壤线虫群落结构的影响。共设置了6个施肥处理:CF(315 kg N·hm^-2,常规施肥量)、N₂₄₀(240 kg N·hm^-2)、N₂₁₀(210 kg N·hm^-2)、N₁₈₀(180 kg N·hm^-2)、F₁₅₀(180 kg N·hm^-2+150 kg·hm^-2黄腐酸)、F₂₂₅(180 kg N·hm^-2+225 kg·hm^-2黄腐酸)。结果表明: 1)氮肥减施会降低土壤线虫数量,降幅为15.3%～68.5%;2)各处理均以原杆属为优势属(19.6%～50.4%)。氮肥减施提高了食真菌类、植食类和捕食/杂食类线虫的丰度,食细菌类线虫的丰度先降低后升高。配施有机肥后,食细菌类和食真菌类线虫的丰度降低,植食类和捕食/杂食类线虫丰度升高;3)N₂₄₀和F₂₂₅处理分别使线虫多样性指数H提高了48.1%和58.5%。N₂₄₀处理线虫成熟度指数MI最高(1.95)。N₁₈₀处理线虫结构指数SI最低(43.33),配施有机肥的F₂₂₅线虫结构指数SI达到62.72,但线虫富集指数EI最低(80.82)。说明减施氮肥并配施有机肥可以提高土壤线虫的多样性,使食物网向复杂稳定方向发展,对农田土壤生态系统有积极意义。

Effects of reduction of nitrogen fertilizer application and combined organic fertilizer on soil nematode community in winter wheat field.

Soil nematodes are one of the typical indicator organisms for soil health. To reveal the effects of reduction in nitrogen fertilizer application on soil health, we examined community structure of soil nematode under reduced nitrogen fertilizer while combined with organic fertilizer at the jointing stage of winter wheat. There were six fertilization treatments, including CF(315 kg N·hm^-2, conventional fertilization), N₂₄₀ (240 kg N·hm^-2), N₂₁₀ (210 kg N·hm^-2)、N₁₈₀ (180 kg N·hm^-2), F₁₅₀ (180 kg N·hm^-2+150 kg·hm^-2 fulvic acid), and F₂₂₅(180 kg N·hm^-2+225 kg·hm^-2 fulvic acid). The results showed that: 1) The reduction of nitrogen fertilization decreased nematode number by 15.3%-68.5%. 2) Protorhabditis was the dominant genus (19.6%-50.4%) across all treatments. The reduction of nitrogen fertilizer application increased the abundance of fungivores, herbivores, and predators-omnivores, while that of bacterivores decreased first and then increased. Combined application of organic fertilizer decreased the abundance of bacterivores and fungivores, while increased that of herbivores and predators-omnivores. 3) N₂₄₀ and F₂₂₅ increased the Shannon diversity (H) of nematode community by 48.1% and 58.5%, respectively. The maturity index (MI) in N₂₄₀ was the highest (1.95), while the structural index (SI) was the lowest in N₁₈₀ (43.33). The structural index (SI) of F₂₂₅ with combined application of organic fertilizer reached 62.72, but its enrichment index (EI) was lowest (80.82). In conclusion, reduced nitrogen fertilizer application and combined with organic fertilizer could improve soil nematode diversity, increase the complexity of soil food web, which would be conducive to the health and stability of agricultural ecosystem.