Experiments on Nitrogen Form for Flue-cured Tobacco Planted in Black Soil

The field plot experiments on effects of the proportion of NO - 3-N to NH + 4-N on agronomic characteristics,chemical components,yield and quality of flue-cured tobacco planted in clay loam soil of middle fertility was conducted from 2000 to 2001. The results showed that when nitrogen application rate was 45 kg/ha with the proportion of 75% NO - 3-N to 25% NH + 4-N,the cured leaves had relatively higher potassium and reducing sugar contents, appropriate proportion of main chemical components related to flue-cured tobacco quality,the best economic indexes in terms of yield value and ratio of high and middle grades tobacco leaves.