In-Situ Determination Of Actual Evapotranspiration Using Zero Flux Method

Abstract

This paper presents a method of determining in-situ actual evapotranspiration using water balance method in the case of maize crop grown for two seasons at the Experimental Farm of the Department of Agricultural Engineering, Federal University of Technology, Akure in a non-saturated soil condition. The crop was subjected to differential irrigation water application using line source sprinkler arrangement. Tensiometers were installed at interval of 10 cm up to 90 cm soil depth. Moisture content was monitored weekly by gravimetric method at an interval of 10 cm up to a depth of 90 cm soil depth. Physical expression and analytical approach of the plane of zero flux method was demonstrated in determining the values of actual evapotranspiration of the maize crop grown in the field. The method was simple to use and did not require the values of hydraulic conductivity, which are often very laborious to determine in the field. The pattern of actual evapotranspiration obtained was parabolic with the peak values at the reproductive stage.

Key words: actual evapotranspiration, differential irrigation, zero flux method, maize crop.

Nig. J. of Pure & Appl. Physics Vol.3 2004: 68-74