滴灌施肥下水氮供应对夏玉米产量、硝态氮和水氮利用效率的影响

【目的】寻找滴灌夏玉米最佳施氮量。【方法】本试验在测坑-防雨棚设施条件下进行,试验设置2个灌水定额,分别为50 mm(WH为充分灌溉)25 mm(WL为限水灌溉);4个氮肥水平,即0、90、180、270 kg/hm~2,分别以N0、N1、N2和N3表示。采用完全区组设计,共计8个处理,3次重复。研究了滴灌施肥条件下,灌水定额和氮肥互作对土壤水分消耗、NO3--N运移积累以及夏玉米产量和水氮利用效率的影响。【结果】灌水、氮肥及其交互作用均显著影响夏玉米地上部干物质量、籽粒产量和水氮利用效率。限水灌溉条件下,玉米拔节期—灌浆初期发生中轻度水分亏缺,对后期产量形成产生显著影响,但限水灌溉显著提高了土壤贮水的消耗量和水分利用效率。在2种灌溉水平下,施氮量与产量均成抛物线关系,充分灌溉条件下施氮量264.3 kg/hm~2时为转折点,限水灌溉条件下施氮量176.9 kg/hm2为转折点。充分灌溉条件下,随着施氮量的增加氮肥农学利用率呈增加趋势;但在限水灌溉条件下,随着施氮量的增加氮肥农学利用率表现出降低的趋势。随着施氮量增加,各土层土壤硝态氮量显著增加,且60～100 cm土层硝态氮累积所占比例增加。与充分灌溉相比,限水灌溉作物吸氮量降低,各生育期土壤中硝态氮残留增加。【结论】玉米产量对氮素的响应与供水量相关,水分亏缺下,产生最大产量需要的氮素用量随之降低。因此,生产中应根据土壤含水率调整施氮量,以实现最高产量和水肥利用效率。

Effects of Irrigation and Fertilization Levels on Grain Yield and Water and N Use Efficiency of Drip-fertigation Summer Maize in the North China Plain

【Objective】The objective of this research is to find suitable N application of drip irrigation.【Method】A field experiment was carried out in the lysimeter and rain-proof shelter facility located at the North China Plain during the maize growing seasons in 2016. The experiment was carried out using a split plot design with irrigation level as the main plots and N level as the subplots. We set two irrigation rates: 50 mm sufficient irrigation(WH), and 25 mm limited irrigation(WL), and four N application rates: 0(N0), 90(N1), 180(N2) and 270(N3)kg/hm~2. the impact of variable irrigation levels, N fertilizer rates and their interaction on water consumption, NO_3~--N movement and accumulation, growth and N and water use efficiency of maize under drip-fertigation condition in the North China Plain was studied.【Result】Irrigation, nitrogen and their interaction significantly influenced maize above-ground biomass, grain yield as well as water and nitrogen use efficiency. Compared to sufficient irrigation, deficit irrigation increased soil water consumption and WUE, but decreased grain yield due to light water deficit during jointing-filling stages. The N application rate and grain yield were presented as quadratic curves under the two irrigation levels. The potential maximum grain yields were attained at 264.3 kg/hm~2 under sufficient irrigation and 176.9 kg/hm~2 under limited irrigation. Under sufficient irrigation, NAE increased with increase of N application rate. By contrast, NAE decreased with increase of N application rate under the deficit irrigation level.With the increase of N application rate, soil NO_3~--N content increased and the ratio of soil NO_3~--N accumulation in60～100 cm soil layer increased. Compared to sufficient irrigation, deficit irrigation decreased N uptake by the crop and increased NO_3~--N accumulation in the soil profile under the high N application rate.【Conclusion】The effect of N fertilizer on grain yield depends on the availability of soil water. Regulating N fertilizer rates to meet maize requirements based on the available soil water content not only increased yield but also prevented negative environmental impacts.