Harnessing Aqua Crop ETo Calculator as New Normal to Generate Reference Evapotranspiration (ETo) for Crop Water Management in Epe, Western Nigeria

Abstract

: Aqua crop ETo calculator was used to generate ETo from 1982 to 2018. Meteorological data were prepared into Aqua crop format in which Aqua crop ETo calculator uses the FAO Penman- Monteith equation. Data obtained from the archive of NASA power (radiation, maximum and minimum temperature, wind speed, and relative humidity) were saved in Micro soft Excel with csv or text file for compatibility in the directory of aqua crop. ETo data generated were processed into annual and seasons of January February March (JFM), April May June (AMJ), July August September (JAS) and October November December (OND). Data were analyzed using descriptive statistics. The results indicated that the annual mean, standard deviation, kurtosis and skewness are 3.53, 0.16, 2.22, and – 1.19 respectively. JFM and OND recorded the highest mean values signaling the peak and onset of the dry season while AMJ and JAS signaling the onset and peak of wet season. OND experiences extreme positive leptokurtic in trend showing that drought is probable and JFM and OND recorded positive regression ETo attributing to the high rate of crop water requirement occasioned by high  evaporative demand of the atmosphere which means that more water is required during dry season by crops. Annual ETo is statistically significant because the P- value is less that 0.05 while JAS and OND are highly statistically significant because their P-values are less than 0.01. Aqua crop calculator proved to be reliable for determination of evapotranspiration especially in a new normal situation- an unfamiliar or atypical situation that suddenly becomes standard, usual orf expected due to unforeseen circumstances.

Key Words: Aqua Crop, ETo Calculator, Reference Evapotranspiration (ETo), Statistically significant, Trend Statistic and New Normal