Crop water and irrigation requirements of some selected crops in southwestern hydrological zone of Nigeria

This study was carried out to determine the crop water and irrigation requirement of some selected crops in southwestern Nigeria. The crops are cucumber, water melon, maize, groundnut, eggplant and tomato. Irrigation requirement and crop coefficient for each crops were determined from the interrelationships of the evapotranspiration, soil type, bulk density, field capacity and the effective root zone of the crops at the selected locations using CROPWAT for windows version 8. Soil parameters used for analysis were determined from laboratory experiment. The crop evapotranspiration and water requirement for cucumber varied from 2.52 to 7.21mm/day and 17 to 73.2mm/dec, respectively, for maize from 1.36 to 6.35mm/day and 5.1 to 63.5mm/dec respectively, for watermelon varied from 2.59 to 6.67mm/day and 25.9 to 73.3mm/dec respectively, for eggplant varied from 1.92 to 6.35 mm/day and 15.9 to 64.4mm/dec respectively. The irrigation requirement for water melon and cucumber recorded the highest value of 461.6 and 497.4mm/dec respectively, an indication that the two crops require more water for physiological activities. The reduction in the values of crop coefficient was observed during the study which could be attributed to the reduction in evapotranspiration at the late stage of growth. The findings also showed that known quantities of irrigation water could be used in producing crops optimally.