| Based on the experimental data from cornfields, this paper compared the daily change of evapotranspiration calculated by Bowen ratio-energy balance and that calculated by lysimeter.The results showed that the evapotranspiration calculated by Bowen ratio was highly related to solar radiation, but that calculated by lysimeter was not evidently related to solar radiation.The diurnal variation curve of evapotranspiration showed the single apex type, it was high in midday, low in the morning and evening, and minus in the night.The results of lysimeter were sensitively affected by its own factors.It was ideal to use the average value of the two methods.The calculated value of Bowen ratio was more accurate than the measured value of lysimeter in describing the evapotranspiration rule of crops in short period. |