The study looked at how nitrogen affects the root system, growth, and yield of high-yield soybeans. They found that adding nitrogen fertilizer increased the number of nodules on the roots, delayed the plant's peak growth period, and boosted the amount of dry matter the plant accumulated. This led to an increase in the overall yield of soybeans. Specifically, using 90 kg of nitrogen per hectare during the flowering stage resulted in a yield of over 5,000 kg per hectare for spring soybeans.