Coefficients and Parameters for Calculation of Evapotranspiration and Yield of Mid-Late Grain Maize Hybrid
2008
Zhivkov, Zh., University of Forestry, Sofia (Bulgaria) | Davidov, D., Institute of Land Reclamation and Agricultural Mechanization, Sofia (Bulgaria)
Based on data from perennial field experiments carried out in the region of Sofia irrigation system, the 10-day values for evapotranspiration and the biophysical coefficient Z for gain maize have been established. The values of the coefficient follow the biological rhythm of the crop and reach their peak in the second half of July (0.24-0.25). The parameters for the yield-evapotranspiration relationship have been established on the basis of data in different irrigation scenarios (0, 30, 50, 70 and 100% of the calculated irrigation rate). The data for the yield and the evapotranspiration have been processed using the method of the least squares with the help of specialised computer software. The formulae of FAO, Davidov and Jensen have been used in the data processing. All three formulae approximate the field data with a relatively high correlation coefficient of R = 0.85. Hence all formulae for the established parameters have equal punctuality and according to the conditions and the data available all three can be used. But to present the relations phase-by-phase it is recommended to use the formulae of Jensen and Davidov.
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