• ISSN 1008-505X
  • CN 11-3996/S

连续秸秆还田条件下陇东旱地玉米高产高效及土壤培肥的氮肥减施策略

Nitrogen reduction strategies for 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。在陇东旱塬区长期秸秆还田条件下，研究全量及不同氮肥减施水平对玉米产量、水分利用效率(WUE)、土壤养分及酶活性的影响，为该区域氮肥优化管理提供依据。
    方法 田间试验始于2021年，在甘肃省农业科学院镇原实验站进行，供试玉米品种为先玉335。以常规施N量 225 kg/hm2 为100%氮肥量，设置处理：秸秆不还田+100%氮肥(N)；在秸秆还田 9000 kg/hm2 基础上，分别施100%、80%、60%氮肥(依次记为NS、80%NS、60%NS)，并设置不施氮肥且秸秆不还田的对照(CK)。连续4年调查玉米产量及其构成因素，并于2024年测定土壤养分含量和酶活性，计算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提高30.2%～35.5%和9.2%～48.7%。同时，0—40 cm土层土壤有机质、全氮、碱解氮和微生物量氮平均含量分别显著提高17.0%、24.0%、32.4%、17.6%；表层0—5 cm土层土壤硝酸还原酶、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分别显著增加14.0%、13.2%；2022年产量无显著差异，但WUE显著提高8.8%；2023年产量和WUE分别显著降低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3年均显著低于NS处理，2023年和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、碱解氮平均含量分别较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，维持或提升土壤肥力。每隔两年进行一次减施 20%氮肥 (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:
    Objectives 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 A field experiment was initiated in 2021 at the Zhenyuan Experimental Station, Gansu Agricultural Academy. The tested maize cultivar was Xianyu 335. The conventional nitrogen application rate (N 225 kg/hm2 ) was defined as 100%N. Five treatments were set up: full N rate without straw return (N); under an annual straw return of 9000 kg/hm2, application of 100%, 80%, and 60% of the full N rate, denoted as NS, 80%NS, and 60%NS, respectively; and a control without N application or straw return(ck). 0−40 cm soil samples were collected after harvest to determine soil organic matter, total and available N, P, and K, microbial biomass nitrogen content (MBN), and enzyme activities. maize yield and its components were investigated, and water use efficiency was calculated over four consecutive years.
    Results Compared with the CK treatment, the combined application of straw return and nitrogen fertilizer significantly increased maize yield and WUE by 68.0%−91.8% and 68.8%−89.4%, respectively. Kernels per ear and 100-kernel weight increased by 30.2%−35.5% and 9.2%−48.7%, respectively. In the 0−40 cm soil layer, soil organic matter, total N, available N, and microbial biomass nitrogen increased by 17.0%, 24.0%, 32.4%, and 17.6%, respectively. in the surface 0−5 cm soil layer, nitrate reductase, nitrite reductase, and urease activities 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; showed no significant effect on yield but increased WUE by 8.8% in 2022; decreased yield and WUE by 9.9% and 11.2% in 2023; and showed no significant differences in 2024. The N treatment achieved similar cumulative yield comparable to NS and 80%NS and also improved soil fertility. Except for 2022, the 60%NS treatment resulted in significantly lower yield and WUE than NS treatment and reduced soil total N, total P, available N, available P, and microbial biomass nitrogen. 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%. Structural equation modeling (SEM) revealed that microbial biomass nitrogen, total N, and available N are key drivers of maize yield.
    Conclusion Under continuous straw return in the Longdong dryland region, full-rate nitrogen fertilizer application can achieve high and stable maize yield while maintaining and enhancing soil fertility. A 20% reduction in N application (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 local environmental and soil conditions, it is not recommended to exceed a 20% reduction in nitrogen application.

     

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