• ISSN 1008-505X
  • CN 11-3996/S

华北马铃薯连作土壤微生物残体氮对氮肥用量的响应

Response of microbial necromass nitrogen to nitrogen fertilization rates in a potato continuous cropping soil in North China

    摘要
  • 摘要:
    目的 微生物残体氮作为一种稳定而重要的土壤氮组分，在维持土壤肥力方面发挥着重要作用。氮肥施用量影响土壤微生物残体氮的转化和积累，研究微生物残体氮对不同施氮量的响应对于优化施氮管理以提高土壤肥力至关重要。
    方法 马铃薯氮肥管理试验始于2017年，在内蒙古自治区武川旱作试验站进行。种植模式为马铃薯连作，试验设置4个处理：NE 肥料用量用NE (Nutrient Expert，养分专家系统)推荐确定、NE−N (不施氮肥)、NE−1/2N (氮肥用量较NE处理减少1/2)和NE+1/2N (氮肥用量较NE处理增加1/2)。于2023年马铃薯收获期，采集0—20 和20—40 cm土层土壤样品，测定土壤矿质氮和微生物残体氮含量，分析马铃薯连作下不同氮肥用量对土壤矿质氮和微生物残体氮的影响。
    结果 氮肥施用处理较NE−N处理增加了土壤全氮(TN)和NO3−-N含量。在20—40 cm土层，土壤NO3−-N和NH4+-N随着施氮量的增加而增加；但在0—20 cm土层，土壤TN、NO3−-N和NH4+-N在3个施氮处理之间没有显著差异。与NE处理相比，NE−N和NE−1/2N处理降低了土壤细菌、真菌和微生物残体氮含量，而NE+1/2N处理并没有增加这些残体氮含量。在所有处理中，真菌残体氮与细菌残体氮的比值随着施氮量的增加而逐渐降低，并且20—40 cm土层中的比值高于0—20 cm土层。在所有处理中，微生物残体氮与土壤全氮的比值达64.2%～73.2%，不同施氮量对0—20 cm深度的比值没有影响；然而，NE−N、NE−1/2N、NE+1/2N处理20—40 cm土层微生物残体氮与土壤全氮的比值较NE处理降低了4.1%～13.2%。NE处理维持了较好的土壤氮平衡，而NE+1/2N处理导致了极大的土壤氮盈余。
    结论 在内蒙古马铃薯连作体系，土壤微生物残体氮随氮肥用量逐步增加，在NE推荐施氮量下获得了较高的微生物残体氮积累。因此，基于NE系统推荐施肥能维持土壤肥力和氮素平衡。

     

    Abstract:
    Objectives Microbial residual nitrogen is a stable and important soil nitrogen (N) component that plays an important role in maintaining soil fertility. The amount of N fertilizer applied affects the changes and accumulation of soil microbial residual N. Understanding the response of microbial residual N to different N application rates is crucial for optimizing N management to improve soil fertility.
    Methods The potato N fertilizer management experiment was conducted in 2017 at the Wuchuan Dry Crop Experimental Station in the Inner Mongolia Autonomous Region, using a potato continuous cropping system with four treatments: NE fertilization recommended using the NE (Nutrient Expert) system, NE−N (no N fertilizer), NE−1/2N (N fertilization rate decreased 50% than NE), and NE+1/2N (N fertilization rate increased 50% than NE). Soil samples from the 0−20 and 20−40 cm soil layers were collected after potato harvest in 2023. The contents of soil mineral N and microbial necromass N were determined, and the effect of different N fertilizer rates on soil mineral N and microbial necromass N under the continuous potato cropping system was evaluated.
    Results N addition increased soil total N (TN) and NO3−-N compared to NE−N. Soil NO3−-N and NH4+-N increased with increasing N rates in the 20−40 cm layer, but soil TN, NO3−-N, and NH4+-N in the 0−20 cm depth did not differ across these three N fertilizer treatments. Compared with NE, NE−N and NE−1/2N decreased soil bacterial, fungal, and microbial necromass N, whereas NE+1/2N did not increase these necromass N. Across all treatments, the ratio of fungal necromass N to bacterial necromass N gradually decreased with increasing N fertilizer rates, and the ratio in the 20−40 cm layer was higher relative to that in the 0−20 cm layer. The proportion of microbial necromass N to soil TN reached 64.2%−73.2% across all treatments. N rates did not affect the proportion in the 0−20 cm depth; however, NE−N, NE−1/2N, and NE+1/2N decreased the proportion of microbial necromass N by 4.1%−13.2% compare to NE in the 20−40 cm layer. The NE treatment maintained a good soil N balance, while the NE+1/2N treatment resulted in a significant soil N surplus.
    Conclusions In the potato continuous cropping system of Inner Mongolia, soil microbial necromass N gradually increased with increasing N rates, and the N fertilization recommended using the NE system achieved higher microbial necromass N accumulation. Therefore, the application of fertilizer based on the NE system can maintain soil fertility and field N balance.

     

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