The R index for plant water requirement

✍ Scribed by A.Y.M. Yao

• Book ID: 102980645
• Publisher: Elsevier Science
• Year: 1969
• Weight: 504 KB
• Volume: 6
• Category: Article
• ISSN: 0002-1571
• DOI: 10.1016/0002-1571(69)90053-3

✦ Synopsis

The frequency distribution model of the monthly and the bi-weekly R index, the ratio of actual evapotranspiration to potential evapotranspiration, is discussed and compared with the Beta distribution. The goodness of fit of the Beta distribution to the R index frequency distribution was tested using the Kolmogorov-Smirnov method for 173 station-month and bi-weekly curves. For values of R < 0.95, the Kolmogorov-Smirnov test specified no rejection, at the 15~ level, of the hypothesis that the R index follows a Beta distribution. With R > 0.95, 36 of the 173 R index curves tested failed the K-S tests. However, R > 0.95 has only very limited value for most agricultural plants.

The probability distribution of R can, therefore, be used as a tool to help solve the problems of agricultural land use capability, long term agricultural planning, irrigation project design, and agricultural drought.