Use of Open Pan Evaporimeter in Scheduling Irrigation for Wheat Crop in South Gujarat

Abstract

An experiment for scheduling irrigation based on irrigation water applied (IW) to cumulative pan evaporation (CPE) ratios was conducted on wheat crop at the Main Irrigation Research Centre, Navsari during the year 1977-78 and 1978-79. Irrigation water of 60 mm (I₁) and 80 mm (I₂) each, as measured by water meter was given at four IW: CPE ratios viz. R₁ = 0.60, R₂ = 0.75, R₁ = 0.90 and R₁ = 1.05 in both the years. The actual values of evapotranspiration for each treatment combination were worked out. It was observed that application of six irrigations each of 80 mm at an IW: CPE ratio of 0.90 was optimum. It gave the maximum yield of 34.24 q/ha with a profit of Rs. 1975/ha, and the water use efficiency of 7.53 kg/ha mm of water applied. The actual evapotranspiration value as observed under this treatment was 450 mm, which had a significant correlation (R = 0.87) with the USWB pan evaporation value.