The researchers studied how applying nitrogen and irrigation water affects the growth and yield of summer cotton. They found that increasing nitrogen fertilizer and irrigation led to higher cotton yield, with the best results seen at a nitrogen level of 180 kg·hm-2 and an irrigation level of 30 mm. More nitrogen increased total nitrogen absorption but decreased nitrogen productivity. The optimal combination for cotton production was found to be nitrogen level 3 and irrigation level 1. This combination resulted in the highest yield and water and nitrogen use efficiency.