The researchers studied how different amounts of nitrogen fertilizer affected soil nitrogen levels, nitrogen release from straw, and grain yield in late sowing wheat with straw returning. They found that higher nitrogen application rates increased soil nitrogen content and nitrogen release from straw. Nitrogen surplus occurred when applying more than 180 kg · hm(-2) of nitrogen, with the highest surplus before jointing. Grain yield was highest at 270 kg · hm(-2) of nitrogen, but higher rates reduced nitrogen use efficiency. Applying 270 kg · hm(-2) of nitrogen improved grain yield in late sowing wheat with straw returning.