Nitrogen effects on vegetable crop production and chemical composition

Concerns about human health in relation to the intake of food have led to a n increasing interest in the nutritional quality of food products. A high i ntake of vitamins, dietary fibres and some minerals, and a low intake of ni trate, is supposed to protect against several life-style diseases which occ ur in many industrialized countries. Application of fertilizers may not onl y influence the yield and quality of field vegetable crops, but also the ch emical composition of the marketable product. Therefore, application of fer tilizers may be used to control and improve the nutritional quality of prod ucts used for human consumption. During the last two decades the chemical composition of field vegetable cro ps has been monitored in several fertilizer experiments at the Danish Insti tute of Agricultural Sciences. This paper shows that increased N supply dec reased the concentration of dry matter, potassium, sucrose, vitamin C, and dietary fibre in leaf vegetable crops, but increased the concentration of n itrate, nitrogen, and carotene.