The study looked at how different ways of adding nitrogen fertilizer to winter wheat crops affected yield and protein content. They tested different nitrogen levels and application times. The results showed that increasing nitrogen levels didn't significantly increase grain yield or protein content. The productivity of nitrogen and water use efficiency decreased with higher nitrogen levels. Basal nitrogen application was better at lower nitrogen levels, while split application was better at higher levels. Water use efficiency improved with higher nitrogen levels, but the fertilization method didn't make a difference.