东北棕壤长期不同施肥处理轮作大豆氮素吸收和土壤硝态氮特征

【目的】在玉米–玉米–大豆轮作体系下,基于棕壤肥料长期定位试验,研究不同施肥处理对东北地区大豆生物量、产量、各部位吸氮量及收获期土壤0―100 cm硝态氮累积的影响,为该地区合理施肥提供理论依据和科学指导。【方法】棕壤肥料长期定位田间试验始于1979年,包括不施肥(CK)、单施氮肥(N)、氮磷钾肥配施(NPK)、低量厩肥(M1)及其与化肥配施(M1N和M1NPK)、高量厩肥(M2)及其与化肥配施(M2N和M2NPK)9个处理。厩肥为猪厩肥,1992年后大豆季不施猪厩肥,仅在玉米季相关处理中施用。39年后,调查分析了大豆生物量、产量、氮素吸收利用及大豆收获期0―100 cm土壤硝态氮累积特征。【结果】高量、低量厩肥配施化肥处理大豆生物量、产量、总吸氮量及各部位吸氮量均显著高于单施氮肥和不施肥处理,其中,M1NPK处理大豆生物量、产量和总吸氮量最高,分别为9107、2979和314.2 k g/h m^2,较其他处理分别提高了6.1%~133.6%、23.9%~232.5%和11.7%~359.4%。施肥提高了大豆氮收获指数,但氮素生理效率降低。NPK和M1NPK处理的氮素收获指数最高,均为63.5%,而氮素生理效率较CK分别降低了30.6%和28.1%。大豆收获期各处理土壤硝态氮累积量随土层深度的增加而降低。与播前相比,大豆收获期单施氮肥处理的0―100 cm土层硝态氮积累量显著增加,NPK处理变化不显著,M1、M1N和M1NPK处理显著降低。低量厩肥配施化肥处理收获期0―100 cm土壤硝态氮积累量远低于高量厩肥配施化肥处理,较播前平均降低了79.2%。所有处理中,土壤硝态氮积累量以M1NPK处理最低,比其他处理平均降低了58.2%。【结论】在东北棕壤地区玉米–玉米–大豆轮作体系下,玉米季低量厩肥(13.5 t/hm^2)与氮磷钾化肥配合施用时,大豆季仅施氮磷钾化肥既可提高大豆生物量、产量,促进氮素吸收,同时还可降低大豆收获期土壤硝态氮累积量,降低环境风险,是该轮作体系较为合理的施肥方式。

Nitrogen uptake of soybean and soil nitrate nitrogen under long-term rotation and different fertilization in a brown soil of northeast China

【Objectives】Based on a long-term fertilization experiment in a brown soil of northeast China, the effects of different fertilization on soybean biomass, grain yield and nitrate N residual in 0–100 cm soil layer were systematically studied in a corn-corn-soybean rotation system. The results would provide theoretical basis and scientific instruction for crop rational application of fertilizer in rotation system.【Methods】A long-term field experiment was initiated in 1979 in brown soil in Liaoning Province. The fertilization treatments included: no fertilizer (CK), N fertilizer alone (N), combined application of N, P and K chemical fertilizers (NPK), manure at low rate (M₁), M₁ combined with N (M₁N) or NPK(M₁NPK), manure at high rate (M₂) and M₂ combined with chemical N (M₂N)or NPK (M₂NPK). The manure was applied only in corn season since 1992. The soybean biomass, yield, N uptake were measured at harvest, and the soil nitrate N residual in 0–100 cm soil layer was determined before seeding and after harvest of soybean in 2018.【Results】The soybean biomass, grain yield and N uptake in treatments of M₁, M₁N, M₁NPK, M₂, M₂N and M₂NPK were significantly higher than those in CK and N. Among all the treatments, the highest soybean biomass, grain yield and total N uptake were all appeared in M₁NPK, which were 9107 kg/hm2, 2979 kg/hm2, and 314.2 kg/hm2, respectively, and were 6.1%–133.6%, 23.9%–232.5% and 11.7%–359.4% higher than those in the other treatments. The highest N harvest index was found in NPK and M₁NPK, which was 63.5%. However, the N physiological efficiency in NPK and M₁NPK were 30.6% and 28.1% lower than that in CK, respectively. Compared with the soil nitrate N before sowing, the soil nitrate N in 0–100 cm layer at harvest was increased significantly in N treatment, did not change significantly in NPK, while reduced significantly in low rate manure treatments, the reduce percentages in M₁ treatments were averaged by 79.2%. At harvest, the lowest nitrate N accumulation in 0–100 cm soil was in M₁NPK, which was 58.2% lower than those in all the other treatments on average.【Conclusions】In the corn-corn-soybean rotation system of northeastern China, the combined application of NPK fertilizer with 13.5 t/hm2 of manure in corn season and application of NPK fertilizer alone in soybean season can increase the nitrogen efficiency of the following soybean, increase its grain yield, and reduce the soil nitrate N residue significantly, which is a suitable fertilization method for this crop rotation system.