覆膜滴灌条件下氮肥运筹对玉米氮素吸收利用和土壤无机氮含量的影响

为解决吉林省半干旱区覆膜滴灌条件下合理施氮问题,通过两年(2016—2017年)田间试验,研究了覆膜滴灌等氮量投入条件下,不同运筹模式(N1:100%基肥;N2:50%基肥+50%拔节肥;N3:30%基肥+50%拔节肥+10%大口肥+10%开花肥;N4:20%基肥+30%拔节肥+20%大口肥+20%开花肥+10%灌浆肥)对春玉米产量、氮素利用效率、关键生长节点氮素积累特征以及生育期内土壤无机氮含量变化和氮素平衡的影响。结果表明,分次施氮各处理(N2、N3、N4)玉米产量显著高于100%基肥处理(N1),其中N4处理玉米产量最高,较N1处理分别提高22.44%(2016年)和35.31%(2017年)。与N1处理相比,N2、N3、N4显著提高了玉米氮素吸收利用率、农学利用率和偏生产力,提高幅度依次为52.02%~83.21%、63.69%~120.78%、11.85%~22.46%(2016年)和92.44%~129.38%、127.23%~203.09%、22.10%~34.01%(2017年),且均以N4处理最高。施氮显著提高了玉米拔节期至成熟期氮积累量,其中开花期至成熟期氮积累量以N4处理最高。与N1处理相比,N2、N3、N4提高了玉米开花期至成熟期0~20 cm土壤无机氮含量,并降低成熟期40~100 cm土壤无机氮含量。土壤-作物系统氮素平衡中,N2、N3、N4处理较N1处理显著降低了氮素表观损失量,其中N4处理氮素表观损失量最低。综上所述,在本试验条件下,总施氮量210 kg·hm-2时,20%基肥+30%拔节肥+20%大口肥+20%开花肥+10%灌浆肥为该区域覆膜滴灌条件下氮肥最佳运筹模式。

Effects of nitrogen fertilizer management on nitrogen absorption, utilization and soil inorganic nitrogen content under film mulch drip irrigation of maize

For reasonable application of nitrogen fertilizer under film mulch and drip irrigation in the semi-arid region of Jilin Province, a field experiment was conducted to investigate the effects of different nitrogen doses on spring maize yield, nitrogen utilization efficiency, nitrogen accumulation characteristics, soil inorganic nitrogen content and nitrogen balance during the growth period. The drip-irrigated film mulch experiment was conducted in 2016-2017 for N1 (100% basal fertilizer), N2 (50% basal fertilizer + 50% jointing fertilizer), N3 (30% basal fertilizer + 50% jointing fertilizer + 10% belling fertilizer + 10% flowering fertilizer) and N4 (20% basal fertilizer + 30% jointing fertilizer + 20% belling fertilizer + 20% flowering fertilizer + 10% filling fertilizer) nitrogen inputs. The results showed that grain yield under N2, N3 and N4 treatments were all significantly higher than that under N1 treatment. The highest maize yield was obtained under N4 treatment, increasing by 22.44% (2016) and 35.31% (2017) over that under N1 treatment. Absorption utilization efficiency, agronomic efficiency and partial factor productivity of nitrogen under N2, N3 and N4 treatments were all significantly higher than those under N1 treatment, respectively increasing in the ranges of 52.02%-83.21%, 63.69%-120.78%, 11.85%-22.46% (in 2016) and 92.44%-129.38%, 127.23%-203.09%, 22.10%-34.01% (in 2017). The highest increase was under N4 treatment. Nitrogen accumulation increased significantly with increasing nitrogen fertilizer application from jointing stage to mature stage, with the highest value under N4 treatment after flowering stage. Compared with N1 treatment, soil inorganic nitrogen content improved at the 0-20 cm soil layer under N2, N3 and N4 treatments after flowering stage, but dropped at the 40-100 cm soil layer at maturity stage. Nitrogen loss significantly reduced under N2, N3 and N4 treatments compared with that under N1 treatment, and it was lowest under N4 treatment in terms of nitrogen balance of the soil-crop system. In conclusion, optimum management strategy was obtained for 20% nitrogen base fertilizer, 30% dose at jointing stage, 20% at belling stage, 20% at flowering stage and 10% at filling stage. This gave a total nitrogen fertilizer application of 210 kg·hm^-2 under the experimental field conditions.