Estimating Crop Evapotranspiration Rates for Spinach in Minna, Niger State

Abstract

Crop evapotranspiration differs in each region depending on crop type, soil and climate conditions. In view of this, this study assessed crop evapotranspiration rates for spinach in Minna, Niger State with the aim of determining the optimum evapotranspiration loss on spinach field in Minna. The study took one soil sample randomly on the plot to compute total depth of water in the root zone and irrigation interval in the month of March and June. The study installed pan evaporation in the crop field (4.17m by 1.70m) and water loss after 24 hours was estimated and multiplied by crop factor 〖(K〗_c) to obtain crop evapotranspiration. The study obtained daily rainfall and temperature data from Nigerian Meteorological Agency (Mimet) between March and June, 2016 to compute evapotranspiration 〖(ET〗_c) for Blaney-Criddle and Thornthwaite. The computed 〖ET〗_o pan evaporation, 〖ET〗_o Blaney-Criddle and 〖(ET〗_c) Thornthwaite were subjected to analysis of variance (ANOVA) and Duncan test. The evapotranspiration losses on spinach field through pan evaporation were 2.8mm/day and 2.38mm/day respectively. The study shows that there was a significant differences between the three methods (p > 0.05, F= 0.0001073). The study concluded that the evapotranspiration losses on spinach field in the month of March were higher than the month of June with the same depth of irrigation. Also, pan evaporation gives optimum evapotranspiration results followed by Blaney-Criddle and Thornthwaite method. The study recommended that there is need to take soil sample of the study area at different growth stages of spinach so as to determine their irrigation intervals.