The researchers studied how using straw mulching and different plant densities can affect the yield and water efficiency of summer maize in North China. They found that medium and high plant densities led to more maize spikes compared to low density. Straw mulching improved both yield and water efficiency, especially in dry years. The treatment with medium plant density and straw mulching had the highest yield and improved water efficiency by 35.4%. This method could be beneficial for farming in the North China Plain.