College of Resources and Environmental Sciences, China Agricultural University, Beijing, China. Key Laboratory of Plant Nutrition, Ministry of Agriculture, Beijing, China. Key Laboratory of Plant-Soil Interactions, Ministry of Education, Beijing, China.
In this study, nitrogen fertilizer was applied to corn (Zea mays L.) at conventional (excessive) and recommended levels, and the growth response was assessed by measuring plant height and stem perimeter. Corn plant maximum height was observed in recommended rates of N fertilizer treatment, and the height without N fertilizer was the same as that receiving excess N fertilizer. Stem perimeter was greatest in the treatment with recommended levels of N fertilizer, followed by the excess N fertilizer treatment. Greater increases in stem perimeter and plant height were observed after application of fertilizer at recommended rates, compared to control without N fertilizer and treatment with excessive N fertilizer, showing that application of N fertilizer at recommended rates results in better growth than that observed after application of fertilizer at excessive rates (i.e. those used in local farming practice). This study shows that soil testing to determine appropriate rates of fertilizer application can reduce fertilizer application rates by more than 50%, while retaining optimum growth in plant height and stem perimeter. Therefore, decreasing application of fertilizer is feasible to reduce environmental pollution and the cost of agriculture.