Fertilizer has helped the growth of agriculture for decades. However, its overuse in some regions has caused environmental and health problems due to pollution and contamination of groundwater. Fertilizer quality is another cause for concern in many countries, as the actual nutrient content may not match the labeled content on the packaging. The North China Plain is a region affected by both fertilizer overuse and quality problems. This study delves into the issue using economic models and survey data of farm households. Is the effectiveness of fertilizer overstated? How do farmers respond to uncertainty in fertilizer quality? Can they differentiate between good and poor quality fertilizer?