The study looked at how different nitrogen fertilizer treatments affect soil nitrogen levels and rice grain yield in a double cropping rice production area with continuous full amount of straw returning. They tested five nitrogen fertilizer treatments and found that applying nitrogen fertilizer increased soil nitrogen content and rice grain yield. Adjusting the ratio of basal dressing to topdressing did not significantly reduce soil nitrogen or rice yield, with a 40% basal dressing and 60% topdressing ratio being the most beneficial. Overall, nitrogen fertilizer application under continuous full amount of straw returning improved soil nitrogen levels and increased rice grain yield and panicle numbers.