The researchers studied how applying phosphate fertilizer at different depths affects the root system of summer maize plants. They found that deeper application of fertilizer led to longer and denser roots, which helped the plants absorb more nitrogen from the soil. This increased nitrogen absorption improved plant growth and grain yield. Specifically, applying phosphate fertilizer at a depth of 15 cm resulted in the highest increase in root growth and nitrogen uptake, leading to a 16.4% increase in grain yield compared to shallow application at 5 cm. Overall, optimizing the depth of fertilizer application can enhance the efficiency of nutrient uptake by maize plants and improve crop productivity.