Experimental Study On The Measuring Method Of Crop Evapotranspiration Using Lysimeter And Bowen-Ratio Energy Balance System

Crop evapotranspiration is the key of the continuous process in the complicated system of soil-plant-atmosphere and the basic to reasonable irrigation and to the management of the water resources. It is significant in the agricultural production.The article makes use of the combination of Bowen-ratio energy balance system, lysimeter and micro-lysimeter to measure the evapotranspiration and evaporation of the winter wheat and maize. Study the laws of the crop evapotranspiration and energy balance and its distribution. This experiment is conducting on the irrigation and drainage experiment field of key laboratory of agriculture soil and water engineering in arid and semi-arid areas by Ministry of Education in Northwest Sci-Tech University of Agriculture and Forestry in Yangling,Shaanxi. The climate in this area can be the presentativeness of the semi-arid and semi-humid district. The results can provide the reference to the studying on the irrigation agriculture in the region of arid and semi-arid in north and plateau in the ocher.Based on the analysis,the main results as follows:1. Compared with the method of the Bowen-ratio and lysimeter,it is suitable for Bowen-ratio to describe the diurnal change evapotranspiration and lysimeter to describe the seasonal change evapotranspiration2. Lysimeter is more exact than the Bowen-ratio except for the day with heavy rain and irrigation.3. The curve of evapotranspiration is the typical unimodal sort,but for the difference with the amplitude , velocity , the size and time of the maximum evapotranspiration.4. In the period of the jointing and spiking,evapotranspiration is the max. And in the period of the germinating,evaporation is the biggest. The proportion of the evaporation of the evapotranspiration is 50% of the maize and 20% of the winter wheat.5. In the different year,the evaporation is the same,the transpiration is dissimilar.6. The diurnal change curve of the solar radiation, solar net radiation, latent flux heat and the soil flux heat is the typical unimodal sort under three different weather conditions. The process of the sensible flux heat has no laws. The change of the solar net radiation and the...