ABSTRACT

Biological nitrogen fixation (BNF) is what makes soybean economically viable. However, the launch of cultivars, with a high-yield potential and abiotic factors that reduce BNF, raised doubts about the need for nitrogen (N) fertilizers for soybeans. The objective of the research was to evaluate the effects of nitrogen supply, in two application times in furrow starter fertilization and top-dressing. The experimental design was in the 3 × 6 factorial scheme. The treatments consisted of three rates of N at in furrow starter fertilization (0, 10, and 20 kg ha⁻¹ of N), and six rates of N in top-dressing, applied at the soybean R1 stage (0, 30, 60, 90, 120, and 150 kg ha⁻¹ of N). The highest rate in furrow starter fertilization of 20 kg ha⁻¹ of N resulted in the increase in the leaf area index (LAI) and specific leaf area (SLA), which are attributes that maximize the absorption of light energy, thus being able to positively influence yield. However, the BNF demonstrated that the strains of the selected Bradyrhizobium are efficient and capable of supplying the required N because the supplementation of nitrogen in furrow and/or top-dressing did not result in significant differences in the yield in relation to inoculated soybean.

摘要

生物固氮 (BNF) 使大豆在经济上可行。然而，具有高产潜力和降低 BNF 的非生物因素的栽培品种的推出引发了人们对大豆是否需要氮肥的怀疑。研究的目的是评估施氮在沟施肥和追肥两个施用时间的影响。实验设计采用 3 × 6 因子方案。处理包括在沟施肥中施用三种氮肥（0、10 和 20 kg ha ^-1 N），以及在大豆 R1 阶段施用六种追肥氮肥（0、30、60 、90、120 和 150 kg ha ^-1 N)。20 kg ha ^-1沟施肥率最高N 的增加导致叶面积指数 (LAI) 和比叶面积 (SLA) 的增加，这些属性可以最大限度地吸收光能，从而能够对产量产生积极影响。然而，BNF 证明所选的慢生根瘤菌菌株是有效的并且能够提供所需的氮，因为在犁沟和/或追肥中补充氮不会导致与接种大豆相关的产量显着差异。