The study looked at how different amounts of nitrogen fertilizer affect the quality and yield of rice in a high latitude region. By conducting field experiments and analyzing soil samples, the researchers found that using a certain amount of nitrogen fertilizer led to the highest yield of rice. They also discovered that applying different types of fertilizer at specific stages of growth increased production. Overall, the study suggests that to achieve a target yield of 9,000 kg per hectare, a specific amount of nitrogen fertilizer should be used.