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A pot experiment was conducted on soil evaporation of flue-cured tobaccounder water and nitrogen fertilizers coupling treatmentsin this study. Soil evaporation at each growth stage of tobacco were analyzed, so did ratio of average soil evaporation (AEa) to mean water consumption (AET). Some factors impacting soil evaporation were also investigated. The results showed that average daily soil evaporation was positively correlated with soil temperature (p), the equation between daily soil evaporation and surface soil moisture (θ) was AEa=0.058e0.048θ (R2=0.717), while relationship between the ratio of evaporation to water consumption (AEa/AET) and leaf area index (LAI ) was functioned as AEa/AET=0.201 LAI-0.912(R2=0.658). It also suggested that the best effects to decrease soil evaporation of flue-cured tobacco appeared in treatment of 6g N per plant combined with the irrigation amount and frequency at 4.5kg and 9 times, 18kg and 18 times, 13kg and 26 times at root spreading stage, vigorous growing stage and the maturing stage respectively.

The experiments were carried out in lysimeters to study water consumption characteristics and water use efficiency of flue-cured tobacco under different conditions of irrigation. By comparing the T and the invalid E of the tobacco K326, it is concluded that in the period of root extending most of the irrigation water is used for the E, in the early vigorous period, plants with all of the treatments show a T higher than the E, in the late vigorous period and the maturity, this ratio remains at 50%. Based on measured data, it was shown that the amount of irrigation water in the vigorous period had the most important influence on the yield of the tobacco.The nonlinear equation of the yield and WUE is Y=-2531.3X2+6113.8X-624.49,R2=0.7324; the equation of the yield and ET is Y=4E-0.7X3-0.0032X2+8.8458X-4806.7, suggesting that the WUE is not maximized at the highest yield of flue-cured tobacco. In the high-yield range, reducing irrigation appropriately could reach the harmonization of high production and water saving.

In allusion to environmental pollution brought about by wastewater irrigation, EM technology was introduced to study the feasibility of EM application in wastewater irrigation. The results show that EC, NO3--N and TN value of EM treatment in shallow groundwater are all less than those of WW treatment as a whole. In all samples, 59.3% NO3--N values are in the alert status, and when irrigation amount reaches 360mm, treatment WW has caused shallow groundwater pollution. TN concentration in treatment WW-3 on June 27 and July 9 is more than 110 mg/L. It suggests that NO3--N can easily penetrate into shallow groundwater with wastewater irrigation and there is insurance of groundwater pollution in the long-term wastewater irrigation. It also indicates that application of wastewater treated by EM reused for irrigation is feasible. TP values are all very low and suggest the pollution of P does not happen.