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Soybean [Glycine max (L.) Merr.] yield and profitability can be affected by plant‐to‐plant spatial uniformity and sowing rate. This study aimed to evaluate the agronomic and economic performance of soybean in relation to the spatial distribution of seeds in rows and seeding rates. A field experiment was conducted during the 2018–2019 and 2019–2020 growing seasons in Londrina, Paraná state, Brazil. We evaluated three coefficients of variation of seed distribution in rows (coefficient of variation of seeds distribution (VDS): 0%, 50%, and 100%) and four seeding rates (350,000, 262,500, 175,000, and 87,500 seeds ha−1), which corresponded to 100%, 75%, 50%, and 25% of the recommended seeding rate of the cultivar BRS 1003 IPRO, respectively. Sowing was performed manually to ensure that seed distribution accurately adhered to the experimental setup. Soybean yield components, yield, and profitability were then evaluated. The lower VDS improved the yield by 374 kg ha−1 compared to the higher VDS and increased the profitability by $334.7 ha−1 in 2019–2020. A seeding rate of 262,500 seeds ha−1 yielded the highest grain yield. The highest soybean profitability was achieved at a seeding rate 6.5% lower than that which produced the highest yield. Branching is essential in compensating for lower seeding rates and plants with uneven spatial distributions. The present study shows that equidistant distribution of seeds in rows optimizes grain yield. Core Ideas: Plant‐to‐plant spatial uniformity increases soybean yield and profitability.Reduced soybean seeding rate increases profitability.Branching is the most important phenotypically plastic mechanism in soybean. [ABSTRACT FROM AUTHOR]

The soybean-maize off-season double cropping is the main grain production system in Brazil. Maize off-season is most commonly grown sole and without topdressing nitrogen (N) fertilization. When used, N fertilizer is commonly applied at rates lower than 100 kg ha− 1. This study aimed to assess the effects of N topdressing rates (0, 60, 120, and 180 kg ha− 1) applied to maize off-season grown sole or intercropped with Urochloa ruziziensis (Ruzigrass) on maize and soybean grain yields, straw production, partial N balance, and soybean oil and protein contents. The experiment was conducted in Londrina, Paraná, Brazil, in the 2020/2021 and 2021/2022 growing seasons. At N rates above 120 kg ha− 1, intercropping with ruzigrass did not affect maize yield. Despite the low N use efficiency of maize off-season, a neutral N balance (i.e. equal to 0) was achieved with 130 kg N ha− 1 in 2020/2021. Considering the average of the two seasons and doses of N, intercropping of maize increased by 14.4% the straw production and by 8.34% the subsequent soybean yield. The N topdressing of sole maize led to an increase in the yield of soybean grown in succession (1.63 and 3.52 kg ha− 1 of grains for every 1 kg ha− 1 of N in 2020/2021 and 2021/2022, respectively). An increase in the N rate applied to maize increased soybean oil content (0.039 g kg-1 in 2020/2021 and 0.044 g kg-1 in 2021/2022 for each 1 kg N ha− 1) and decreased protein content (-0.085 g kg-1 in 2020/2021 and -0.088 g kg-1 in 2021/2022 for each 1 kg N ha− 1) in soybean grains. [ABSTRACT FROM AUTHOR]