• ISSN 1008-505X
  • CN 11-3996/S

连续秸秆还田条件下陇东实现旱地玉米高产高水效及土壤培肥的氮肥减施策略研究

Nitrogen reduction strategy for sustainable efficient maize production and soil fertility improvement under continuous straw return in eastern Gansu Province

    摘要
  • 摘要:
    目的 施用氮肥可显著提升土壤氮素有效性、改善养分状况、实现作物增产和土壤培肥。我们在陇东旱塬区，研究了长期秸秆还田条件下，全量及不同减施氮肥量对玉米产量、水分利用效率(WUE)、土壤养分及酶活性的影响，为优化该区域氮肥管理提供依据。
    方法 田间试验始于2021年，在甘肃省农业科学院镇原试验站进行，供试玉米品种先玉335。试验处理以常规施N量 225 kg/hm2 为100%氮肥量，设置：秸秆不还田+100%氮肥(N)，以及在秸秆还田 9000 kg/hm2 基础上，施100%、80%、60%氮肥处理(依次记为NS、80%NS、60%NS)，并保留一个不施氮肥也不秸秆还田的空白对照(CK)。连续4年调查了玉米产量及其构成因素，并于2024年测定了土壤养分含量和酶活性，计算了WUE。
    结果 秸秆还田与氮肥配施较CK处理显著提高旱地玉米产量和WUE，增幅分别为68.0%～91.8%和68.8%～89.4%，穗粒数和百粒重分别显著增加30.2%～35.5%和9.2%～48.7%，显著提高了0—40 cm土层有机质、全氮、碱解氮和微生物量氮平均含量17.0%、24.0%、32.4%、17.6%，表层0—5 cm土壤硝酸还原酶、亚硝酸还原酶、脲酶活性分别提高6.1%、22.2%、6.8%。与NS处理相比，80%NS处理2021年产量和WUE显著增加14.0%、13.2%；2022年产量无显著差异，WUE显著提高8.8%；2023年产量和WUE显著降低9.9%、11.2%；2024年产量和WUE无显著差异。N处理累积产量、土壤有机质和养分含量与NS和80%NS处理无显著差异。60%NS处理产量和WUE除2022年外，其余三年均显著低于NS，2023和2024年土壤全氮和全磷含量以及速效氮磷和微生物量氮显著低于NS处理。80%NS处理0—40 cm土层全磷、速效磷、碱解氮平均含量较NS处理降低8.4%、9.1%、15.9%，但微生物量氮平均含量显著提高了7.5%。SEM模型分析显示，微生物量氮、全氮、碱解氮是旱地玉米产量的关键驱动因子。
    结论 在陇东旱塬区连续秸秆还田条件下，施用全量氮肥可实现玉米高产稳产，维持且提升土壤肥力。每隔两年进行一次减N 20%(180 kg/hm2)，可显著提高旱地玉米产量和水肥利用效率，提高土壤有机质及全氮含量，不降低土壤有效氮磷含量，避免减氮带来的产量和土壤肥力下降风险。鉴于当地环境和土壤条件，减氮幅度不建议超过20%。

     

    Abstract:
    Objective Nitrogen application can effectively enhance soil fertility and nutrient availability, and maintain high and stable crop yield. We studied the effects of full and reduced nitrogen application rates on dryland maize yield, water use efficiency (WUE), and soil fertility indicators under continuous straw incorporation in Loess Plateau of Eastern Gansu Province, to provide a basis for optimizing nitrogen fertilizer management in the region.
    Methods Localized field experiment was started since 2021 at Zhenyuan Experimental Station of Agricultural Academy of Gansu Province. The tested maize cultivar is Xianyu335, and the full nitrogen application rate is N 225 kg/hm2. Five treatments were set up: full N rate without straw return (N); at a annual straw returning amount of 9000 kg/hm2, applying 100%, 80%, and 60% of full N rate, denoted as NS, 80%NS, and 60%NS; and a control was made without nitrogen application nor straw return. 0−40 cm soil samples were collected for measurement of organic matter, total and available NPK content, microbial biomass nitrogen content (MBN), enzyme activities after harvest of maize. At the same time, maize yield and its components were investigated, and water use efficiency was calculated over four consecutive years.
    Results Compared to the CK treatment, the combination of straw returning and nitrogen fertilizer significantly increased maize yield and WUE by 68.0%−91.8% and 68.8%−89.4%, respectively; enhanced kernels per ear and 100-kernel weight by 30.2%−35.5% and 9.2%−48.7%, respectively; elevated the average contents of soil organic matter, total N, available N, and microbial biomass nitrogen in the 0−40 cm soil layer by 17.0%, 24.0%, 32.4%, and 17.6%, respectively; increased nitrate reductase, nitrite reductase, and urease activities in the surface 0−5 cm soil layer by 6.1%, 22.2%, and 6.8%, respectively. Compared with the NS treatment, the 80%NS treatment significantly increased yield and WUE by 14.0% and 13.2% in 2021; did not show significant effect on yield but increased WUE by 8.8% in 2022; decreased yield and WUE by 9.9% and 11.2% in 2023; did not change yield and WUE significantly in 2024. The N treatment achieved similar cumulative yield with NS and 80%NS, and demonstrated a clear soil improvement and fertility enhancement effect. Except 2022, 60%NS treatment had significantly lower yield and WUE,relative to NS treatment, in addition, 60%NS treatment recorded significantly lower soil total N, total P, available N, available P, and microbial biomass nitrogen than NS treatment. Compared to the NS treatment, the 80%NS treatment reduced the average contents of total P, available P, and available N in the 0−40 cm soil layer by 8.4%, 9.1%, and 15.9%, respectively, but significantly increased the average microbial biomass nitrogen content by 7.5%. SEM model analysis revealed that microbial biomass nitrogen, total N, and available N are key drivers of maize yield.
    Conclusion Under the condition of continuous straw returning in the Longdong dryland region, the application of full-rate nitrogen fertilizer can achieve high and stable maize yield while maintaining and enhancing soil fertility. Reducing nitrogen application by 20% (180 kg/hm2) every two years can significantly increase maize yield and water-fertilizer use efficiency, improve soil organic matter and total nitrogen content, without reducing soil available nitrogen and phosphorus levels, thereby avoiding the risks of yield decline and soil fertility reduction associated with nitrogen reduction. Given the local environmental and soil conditions, it is not recommended to exceed a 20% reduction in nitrogen application.

     

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