Fate of water and N nutrient in tobacco field under different water-nitrogen coupling treatments

The fate of water and fertilizer N in tobacco fields was observed and analyzed under the condition of lysimeter experiments. Results showed that the proportion of plant transpiration (y 1 ), soil evaporation (y 2 ) and soil water storage variation (y 3 ) accounted for the total water consumption was 60.29%-77.63%, 20.25%-37.83% and 1.49%-2.33% respectively, presenting an exponential relationship with the irrigation amount by the formula of y 1 = 26.55 exp (0.0026x), y 2 = 305.73 exp (0.0007x) and y 3 = 4.53 exp (0.0015x). The average fertilizer N uptake proportion of upper leaf, middle leaf and lower leaf of tobacco plant was 21.96%, 24.07% and 30.09% separately. Fertilizer N remained in soil accounted for more than 60% of the total fertilizer N application in season, which was decreased with the depth of soil layer. N loss was relatively less and significantly related to amount of N fertilizer application, with highest of T6 recorded as 24.6 kg hm -2 , it seemed that both the highest irrigation amount and N application amount could lead to an easy leaching of fertilizer N.