施氮对不同肥力土壤小麦氮营养和产量的影响

【目的】农田养分供应是由土壤基础肥力和肥料投入共同决定的,不同土壤肥力下土壤养分供应能力和特征也不同。本文研究了河南省高、低肥力田块下,不同施氮量对小麦主要生育时期植株氮素营养和土壤硝态氮及产量的影响,以期为河南省同类生产条件下氮肥的合理施用和产量的提升提供参考和依据。【方法】2015—2016年,以小麦品种矮抗58为供试材料进行大田试验,分别设置0、120、225、330 kg/hm^2 4个施氮处理(表示为N0、N1、N2、N3),在开花期到成熟期调查施氮量对土壤硝态氮及产量的影响;在开花期、花后10天和花后20天,测定施氮量对小麦旗叶到倒4叶的叶片氮含量、SPAD值和氮素积累量,以及对植株和所有叶片氮含量的影响。【结果】从开花期到成熟期土壤中硝态氮含量随着施氮量的增加而增加,高肥力田块的土壤硝态氮含量显著高于低肥力田块的土壤硝态氮含量。施氮能显著增加低肥力田块产量,但是高肥力田块的产量均高于低肥力田块,与不施氮相比,低肥力田块的产量最大增幅是高肥力田块产量最大增幅的2.63倍。N1和N2处理下,在开花期和花后10天倒2叶的SPAD值高肥力田块显著高于低肥力田块,但在花后20天低肥力田块显著高于高肥力田块。在N1、N2和N3处理下,旗叶的氮含量在花后10天高肥力田块显著高于低肥力田块,但在花后20天则显著相反。开花期到花后20天,对于低肥力田块旗叶的氮素积累量对上4叶的贡献率最大(N0除外),最高达52.6%;高肥力田块,旗叶和倒2叶对上4叶的氮素积累量贡献率处在同等重要的位置,最高分别达39.9%和39.7%。花后10天到花后20天,高肥力田块不同叶位的氮素转运量和转运率均高于低肥力田块(N0除外)。【结论】增施氮肥可以通过提高土壤硝态氮含量来提高土壤供氮能力,高肥力田块的叶片转运量和转运率比低肥力田块高,低肥力田块通过提高施氮量增加的产量低于高肥力田块下的产量,因此,需改善农田基础肥力来提高产量。通过对高、低肥力条件下产量的分析发现,达到最高产量时的施氮量分别为213kg/hm^2和287 kg/hm^2。

Effect of nitrogen application on nitrogen nutrition and yield of wheat in fields of different fertility

【Objectives】Nutrient supply of a field is determined by its soil fertility and fertilizer application. Soils with different fertility levels have different nutrient supply capacity and characteristics. This study looked at the effects of nitrogen application rates on spatial and temporal distribution characteristics of nitrogen in soil and grain yield in fields with different fertility in Henan Province to provide a reference and basis for rational use of nitrogen fertilizer and improvements in yields.【Methods】A field experiment using four nitrogen rates (0, 120, 225, 330 kg/hm2, represented as N0, N1, N2, N3) and Aikang58 as the wheat cultivar was conducted from 2015 to 2016. Soil nitrate concentration and yield from anthesis to maturity, dynamics of leaf nitrogen concentration, SPAD value, nitrogen accumulation of leaves of different positions, and nitrogen concentration of whole plant and all leaves at the anthesis, 10 days after anthesis and 20 days after anthesis stage were measured.【Results】Nitrate concentration in soil increased with nitrogen application rates from the anthesis to maturity, and nitrate concentration in field of high fertility was significantly higher than that of low fertility field. While nitrogen application significantly increased grain yield in the low fertility field, the yield of high soil fertility field was higher than that of the low soil fertility field. The yield increase with nitrogen application in low soil fertility field was 2.63 times that of high soil fertility field compared with no nitrogen treatment. Although SPAD value of the flag leaf and the second leaf from the top in the N1and N2 treatments of the high fertility field at anthesis and 10 days after anthesis was higher than that of the low fertility field, the trend was the opposite at 20 days after anthesis. Although nitrogen concentration of the flag leaf of N1, N2 and N3 in the high fertility field at 10 days after anthesis stage was higher than that of the low fertility field, the trend was opposite at 20 days after anthesis. In the low fertility field, the contribution of the flag leaf to nitrogen accumulation of the top four leaves was the biggest (52.6%) (except the N0 treatment); the contribution of the flag leaf and the second leaf from top to nitrogen accumulation of the top four leaves was the biggest (39.9% and 39.7%) respectively. The amount and rate of nitrogen translocation of different leaves of the high fertility field were generally higher than those of the low fertility field.【Conclusions】Nitrogen application increased soil nitrate concentration and soil nitrogen supplying capacity. The amount and rate of nitrogen translocation of different leaves in the higher fertility field were generally higher than those in the lower fertility field. As the yield of the lower fertility field still cannot reach that of the high fertility field, improvement of soil fertility and optional fertilizer input should be considered for improving yield. The highest nitrogen application rates for the maximum yield are 213 kg/hm2 and 287 kg/hm2 for the high and low fertility fields, respectively.