Flue-cured Tobacco Fertilization:Absorption and Utilization of ¹⁵N in Cake and Straw Manures

Blending with mineral fertilizers and under different fertilization conditions, the absorption and utilization of nitrogen in cake and straw manures were studied with ¹⁵N isotopic tracing technology.The results showed that:1) the nitrogen absorbed by flue-cured tobacco from cake and straw manures was basically in accord with an "S" curve, and the utilization rates of nitrogen were higher in the treatments of 25% cake manure +75% NH4NO 3 and 25% straw manure +75%NH₄NO₃(all of them used as base fertilizers), which were 94.31%and 59.58%, respectively;2)the nitrogen absorbed by flue-cured tobacco roots was provided for the most vigorous organs, the tips, firstly, then for upper and lower leaves, less for stalks and the least for roots;3)the organs in order of nitrogen distribution were tips > upper leaves > middle leaves > lower leaves > stalk > root, and the nitrogen content in leaves was desirable in the treatments mentioned above.