施氮和燕麦/箭筈豌豆间作比例对系统干物质量和氮素利用的影响

【目的】 本研究于大田试验条件下探究了燕麦 (Avena sativa L.)/箭筈豌豆 (Vicia sativa L.) 间作系统饲草干物质产量、土地当量比 (LER) 及氮素吸收利用等对施氮和不同间作比例的响应，以期为该地区多元化粮改饲种植模式的建立提供理论依据。 【方法】 大田试验于2012年在兰州大学庆阳黄土高原试验站进行，设不施氮 (N₀) 和施氮N 46 kg/hm2 (N₄₆) 两个氮水平，在每个氮水平下各设7个燕麦与箭筈豌豆间作比例 (1∶0、4∶1、2∶1、1∶1、1∶2、1∶4和0∶1)。于箭筈豌豆的花期和乳熟期，测定并分析了饲草的干物质产量、土地当量比及吸氮量；在花期，分析测定了箭筈豌豆的生物固氮量；在箭筈豌豆的乳熟期，分析了不同间作比例下间作系统的氮肥偏生产力 (PFP_N)。 【结果】 生长至第60 d (花期) 和第90 d (乳熟期) 时，N₄₆水平下系统的平均干物质总产量较N₀水平分别提高了31.6%和24.2%；N₀水平下系统的干物质产量分别在2∶1和1∶0下达到最大值，较箭筈豌豆单作分别提高了102.5%和107.9%，N₄₆水平下分别在1∶1和4∶1下最大，较箭筈豌豆单作分别提高了103.5%和111.1%。生长至花期 (第60 d) 时，N₀水平下间作系统的LER值均大于1，生长至乳熟期 (第90 d) 时，N₄₆水平下除4∶1外均小于1。施氮后箭筈豌豆的生物固氮量降低了50.6%，燕麦的吸氮量占比平均增加了17.2%。4∶1间作比例下系统的氮肥偏生产力 (PFP_N) 最大。无论施氮与否，燕麦相对于箭筈豌豆的氮素营养竞争比率 (CR_OV) 在4∶1间作比例下均达到最大值，之后随着箭筈豌豆种植比例的增加而呈降低趋势。 【结论】 施氮提高了间作系统中燕麦的吸氮量占比和体系干物质总产量，但降低了箭筈豌豆的固氮量。在4∶1间作比例下，系统具有较高的作物产量、土地当量比和氮肥利用效率。

Effects of nitrogen application and intercropping ratio on dry matter production and nitrogen use efficiency of the oat and common vetch intercropping system

【Objectives】 This paper investigated the effects of nitrogen application and different intercropping ratios on dry matter yield, land equivalent ratio (LER) and nitrogen use efficiency of the oat and common vetch intercropping system, in order to provide a theoretical basis for the diverse production of grain and feed crops in the region. 【Methods】 A field experiment was conducted in the oat (Vicia sativa L.) and common vetch (Avena sativa L.) intercropping plots located inside the Qingyang Loess Plateau Experiment Station of Lanzhou University in 2012. Seven oat to vetch intercropping ratios were set up, including 1∶0, 4∶1, 2∶1, 1∶1, 1∶2, 1∶4 and 0∶1 under the condition of N application rate of N 46 kg/hm2 (N₄₆) and no nitrogen application (N₀). The dry matter yield, land equivalent ratio, nitrogen uptake were measured in the flowering and milk-ripe stage of common vetch, the amount of biological nitrogen fixation of common vetch was analyzed in the flowering stage, and the partial factor productivity from applied N (PFPN) of the intercropping systems was analyzed in the milk-ripe stage of common vetch. 【Results】 The average total dry matter yields of the intercropping system under N₄₆ were significantly increased by 31.6% and 24.2% compared with those under N₀ at the 60 d (flowering stage) and 90 d (milk-ripe stage) after the emergence. Compared with the common vetch monoculture, at the 60 d and 90 d after the emergence, the dry matter yields of the intercropping system at the N₀ level reached the maximum at the intercropping ratios of 2∶1 and 1∶0, which were increased by 102.5% and 107.9%; at the N₄₆ level those were increased by 103.5% and 111.1% at 1∶ 1 and 4∶1. At the 60 d, the LER values were greater than 1 in all intercropping ratios in the N₀ level, and at the 90 d, the LER values of the intercropping system were less than 1 except for 4∶1 intercropping ratio at the N₄₆ level. The biological nitrogen fixation (BNF) of the common vetch was decreased by 50.6%, and the average N uptake rate of oats was increased by 17.2% after the nitrogen application. The partial factor productivity from the applied nitrogen (PFP_N) of the intercropping system was the highest in the 4∶1 intercropping ratio. Regardless of applied nitrogen or not, compared with common vetch the ratio of nitrogen nutrition competition (CR_OV) of oats was the highest in the 4∶1 intercropping ratio, and then decreased with the increase of the cultivation proportion of common vetch. 【Conclusions】 The nitrogen fertilization promoted the N uptake ratio of oat and the total dry matter production of the system, but decreased the nitrogen fixation amount of the common vetch. The intercropping system had higher crop yield, land equivalent ratio and nitrogen use efficiency in the 4: 1 intercropping ratio.