An estimate of potential evapotranspiration is acquired to implement an irrigation scheduling program. Four equations, which estimate potential evapotranspiration (evaporation) were evaluated for prediction of Class "A" Pan evaporation. The equations used were Penman's combination equation, the Jensen-Haise temperature and radiation equation, and two of the Christiansen-Hargreaves polynomial regression type equations. Measured and calculated radiation was used together with two values of albedo. Four years of daily climate data from Rhodesia was evaluated by general linear regression methods.
Despite the significant variations between the four annual regression lines of each equation, the use of confidence intervals indicate that the Penman and Christiansen-Hargreaves equation adequately predict Class "A" pan evaporation for irrigation control purposes.
Using class "A" pan evaporation as the measure of potential evapotranspiration for sugarcane, a computerized irrigation scheduling model was developed.
Controlled plant moisture stress was incorporated in the program with an irrigation coefficient related to the limiting effects of low soil moisture on plant transpiration. Five soil moisture regimes and two levels of irrigation were studied.
Within the limits of the defined soil moisture assumptions, the program exhibited considerable flexibility in computation and the control of desired plant moisture stress.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-5588 |
| Date | 01 May 1976 |
| Creators | Pearse, Terence L. |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
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