EVALUATION OF IRRIGATION WATER REQUIREMENTS OF SOME CROPS IN DADINKOWA DAM IRRIGATION SCHEME OF NIGERIA

Evapotranspiration is important in evaluation of the irrigation potentialities of various agricultural zones and helps improve the practices of water management and crop production. In this study, meteorological data were collected from Upper Benue River Basin Development Authority, Area office Dadinkowa, Gombe state, Nigeria for the last 15 years (2001-2015). Cabbage, sweet pepper, sweet melon, tomato, wheat and small vegetables were planted during the dry season on the 1st of November. FAO-CROPWAT 8.0 model was used to determine reference evapotranspiration (ETo) and Crop water requirement (CWR) of various crops grown in Dadinkowa area using crop coefficient and ETo. The results from CROPWAT model showed that reference evapotranspiration (ETo) in the study area varied from 3.83 to 5.55 mm/day and effective rainfall of 611.18mm. CWR of cabbage varied from 2.80 to 5.49mm/day, sweet pepper varied from 2.40 to 4.43mm/day, sweet melon varied from 2.03 to 4.30mm/day, tomato varied from 2.40 to 5.18mm/day, wheat varied from 1.20 to 4.66mm/day and small vegetables varied from 2.84 to 3.93mm/day. The scheme irrigation requirement (NIWR) ranged between 0.04 to 0.42 l/s/ha or 0.3 to 3.6 mm/day with an application efficiency of 50%. The gross irrigation requirement of scheme is 206MCM; therefore the dam capacity of 800MCM can meet three times this requirement. For areas such as Dadinkowa, where measured data on climate are readily available, an adaptation of the CROPWAT model serves a tool for the determination of crop and irrigation water requirements of the area and for irrigation planning and management.