The study looked at how different ways of adding nitrogen to maize fields affect the crop's growth and yield. They found that a specific nitrogen application method increased maize yield, nutrient absorption, and profit. The best way to apply nitrogen was to use 200 kg/ha, with 1/5 at the beginning, 2/5 during jointing, and 2/5 during the big bell stage. This method worked well for spring maize in the black soil zone.