Methods Determination of Alfalfa Potential Evapotranspiration and Crop Coefficent by Lysimeter and Comparison with Empirical Methods.
2001
Dadivar, Mosoud | Talebnejad, Ali Reza | Rostami, Asadolla | Gadbeykloo, Javad
In according to water resources limitation in Iran, determination of crop water requirement is important. In this study, water requirement of alfalfa was determined by drainage lysimeter at Arak Research Station in four years (2001-2004). The results showed that the alfalfa evapotranspiration potential in four years with 7 month-period (21 mar-21 oct) measurements were 1343.8, 1364.5, 1324.2 and 1326,4 mm respectively, with an average 1339.7 mm. Blaney- Criddle, Radiation, Hargreaves- Samani and Penman- Monteith methods estimated ET values 1485.0, 1581.8. 1109.3 and 1589.6 mm respectively. Crop coefficients (Kc) were 0.91 , 0.94 m 0.91 and 1.00 respectively for four years. Mean of fresh alfalfa yield was 72 and 68 tonha"' inside and outside of lysimeter respectively. Correlation coefficient between ET estimated by lysimter and methods was as following : Blaney- Criddle 0.989" , Hargreaves- Samani 0.995" , Radiation 0.953" and Penman- Monteith 0.969" The highest of 95% confidence interval and the lowest of standard deviation and standard error mean was observed by Hargreaves- Samani method. Key word: Lysimeter, Alfalfa, Blaney - Criddle, Radiation, Hargreaves- Samani, Penman- Monteith, Potential evapotraspiration
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