• ISSN 1008-505X
  • CN 11-3996/S

秸秆还田配施适量氮肥提升土壤氮库以及高效稳定供应氮素的能力

Straw returning combined with suitable amount of nitrogen fertilizer improves soil nitrogen storage and efficient and stable nitrogen supply to crop

    摘要
  • 摘要:
    目的 探究秸秆还田配施不同氮肥量对土壤全氮、活性氮组分含量以及玉米氮肥利用率的影响，为氮肥减施增效和秸秆高效还田提供理论依据。
    方法 于2021—2023年在甘肃引黄灌区灰钙土上进行田间试验，分别在秸秆不还田和秸秆还田条件下，设置0、375、450 kg/hm2 3个施氮水平，共6个处理，分别记作N0、N375、N450和SN0、SN375、SN450。于2023年收获后测定玉米产量、地上部氮素累积量，同时取0—40 cm土层土样，测定全氮、NO3−-N、NH4+-N、可溶性有机氮(DON)、颗粒有机氮(PON)、和微生物量氮(MBN)含量。
    结果 SN375处理玉米产量、氮素积累量较N375显著增加8.58%、9.21%，氮肥利用率较N375、N450和SN450分别显著提高17.98%、57.12%和38.92%；在0—20 cm土层，SN375处理较N375显著增加了土壤TN、DON、PON和MBN含量，较N450显著增加了土壤DON、PON和MBN含量，SN450较N375和N450均显著增加了土壤DON、MBN含量，而且SN375、SN450较N375、N450均显著降低了NO3−-N含量。在20—40 cm土层，SN375处理较N375显著增加了土壤TN、NH4+-N、DON、PON和MBN，较N450显著增加了土壤TN、DON、PON和MBN，SN450处理较N375和N450均显著增加了土壤TN、DON和MBN含量。此外，SN375显著增加了20—40 cm土层PON/TN、MBN/TN、NH4+-N/TN以及0—40 cm土层NO3−-N/TN，SN450显著增加了0—20 cm土层MBN/TN、DON/TN和0—40 cm土层NO3−-N/TN；在0—40 cm土层，PON、MBN、DON、NO3−-N和NH4+-N与全氮、氮素累积量、氮肥利用率均呈显著相关关系；在0—20 cm土层，PON、NH4+-N和NO3−-N与产量显著或极显著相关，20—40 cm土层，DON、NO3−-N与产量显著或极显著相关。
    结论 甘肃引黄灌区灰钙土上，施用氮肥对提高土壤氮素储量、增加氮素供应和保肥能力的作用不可替代，长期单一减施氮肥有降低土壤地力和作物产量的风险。秸秆还田与适宜的施氮量配合可提升作物对氮的吸收利用率，减少耕层硝态氮的积累，增加0—40 cm土层中可溶性、颗粒态有机态氮和微生物量氮，显著提升氮肥在提高土壤保肥和稳定供肥能力的效果。施氮量过高反而会降低秸秆还田提高氮肥效率、降低环境风险的效果。

     

    Abstract:
    Objectives This study aimed to investigate the impact of straw return combined with nitrogen application on soil active nitrogen components, maize yield, and nitrogen use efficiency (NUE), thereby providing a theoretical foundation for nitrogen fertilizer reduction and efficient straw return technologies.
    Methods A field experiment was conducted from 2021 to 2023 on lime-calcareous soil in the Gansu Yellow River Diversion Irrigation Area. Under conditions of no straw return and straw return, three nitrogen application levels (0, 375, and 450 kg/hm2) were set, resulting in a total of six treatments: N0, N375, N450, and SN0, SN375, SN450, respectively. After the second year's harvest, maize yield, above-ground nitrogen accumulation, and NUE were measured. Additionally, soil samples from the 0−40 cm layer were collected to determine soil total nitrogen (TN), nitrate nitrogen (NO3−-N), ammonium nitrogen (NH4+-N), soluble organic nitrogen (DON), particulate organic nitrogen (PON), and microbial biomass nitrogen (MBN) content.
    Results Compared with N375, SN375 significantly increased maize yield and above-ground nitrogen accumulation by 8.58% and 9.21%, respectively. Moreover, the NUE of SN375 was significantly higher than that of N375, N450, and SN450 by 17.98%, 57.12%, and 38.92%, respectively. In the 0−20 cm soil layer, SN375 significantly increased soil TN, DON, PON, and MBN content compared with N375, and significantly increased soil DON, PON, and MBN compared with N450. SN450 significantly increased soil DON and MBN content compared with N375 and N450, while both SN375 and SN450 significantly decreased soil NO3−-N content. In the 20−40 cm soil layer, SN375 significantly increased soil TN, NH4+-N, DON, PON, and MBN content compared with N375, and significantly increased soil TN, DON, PON, and MBN compared with N450. SN450 significantly increased soil TN, DON, and MBN compared with N375 and N450. SN375 significantly increased PON/TN and MBN/TN ratios in the 20-40 cm soil layer, while SN450 significantly increased MBN/TN and DON/TN ratios in the 0−20 cm soil layer and NO3−-N/TN ratio in the 0-40 cm soil layer. In the 0−40 cm soil layer, PON, MBN, DON, NO3−-N, and NH4+-N were significantly correlated with TN, above-ground nitrogen accumulation, and NUE. In the 0−20 cm soil layer, PON, NH4+-N, and NO3−-N were significantly or extremely significantly correlated with yield, while in the 20−40 cm soil layer, DON and NO3−-N were significantly or extremely significantly correlated with yield.
    Conclusions In lime-calcareous soil in the Gansu Yellow River Diversion Irrigation Area, nitrogen fertilizer application plays an irreplaceable role in enhancing soil nitrogen storage, nitrogen supply, and fertilizer retention capacity. However, long-term single nitrogen fertilizer reduction may risk decreasing soil fertility and crop yield. Combining straw return with an appropriate amount of nitrogen fertilizer can enhance nitrogen absorption and utilization rates, reduce nitrate nitrogen accumulation in the plough layer, and increase soluble, particulate organic nitrogen, and microbial nitrogen content in the 0−40 cm soil layer, significantly improving the effect of nitrogen fertilizer in enhancing soil nutrient retention and stable nutrient supply capacity. Excessive nitrogen application may reduce the effectiveness of straw return in improving nitrogen fertilizer efficiency and mitigating environmental risks.

     

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