The researchers wanted to see how changing when maize is planted and how much nitrogen is used affects how much maize is grown and how efficiently the plants use nitrogen. They did experiments with different planting dates and nitrogen levels for both rainfed and irrigated maize. They found that planting maize on time with more nitrogen increased grain yield. Late planting led to lower yields. Using higher nitrogen levels also increased grain yield, but efficiency in using nitrogen decreased. The study showed that combining the right planting dates with the right amount of nitrogen can boost grain yield and nitrogen use efficiency.