Crop responses to nitrogen overfertilization: A review

• Rational nitrogen fertilization practices are encouraged not only for environmental constraints.
• High nitrogen fertilization rates are detrimental for crop yield.
• Several quality parameters in fruits and vegetables are negatively affected.
• Law enforcement is restricting the content of N in certain vegetables.

Nitrogen-containing fertilizers are commonly used in modern agriculture, but the application rate in most fields exceeds crop demand, with short- and long-term negative consequences. Reduction in the quality of the products, assessed by organoleptic characteristics and compounds related to health, such as nitrate, are commonly reported. Even yield losses, depending on site-specific conditions, can result from N overfertilization. This literature review summarizes the research of the past 20 years that describes the response of crops to high rates of N fertilization, with a detailed analysis of the conditions and agricultural practices that lead to nitrate accumulation in leafy green vegetables.