Nitrogen management of vegetable crops

N fertilization is often viewed as a cheap insurance against yield loss in vegetable production because of the generally large added value, resulting in application of fertilizer N often in excess of actual crop demand. In combination with the low fertilizer N recovery by many vegetable crops and the often excessive irrigation, this may lead to both health and environmental risks related to high nitrate concentrations in water leaving the root zone. In this review, we discuss the decisive factors in the overall N balance of field vegetable production systems and the different tools at hand to increase fertilizer use efficiency and consequently reduce N losses to the environment. Based on this, we identify areas of research and technology transfer where further work is required. Only an integration of the different methods and strategies for N management may really mitigate the risk of nitrate leaching and maintain crop yields while enhancing the environmental sustainability of vegetable production systems