Crop coefficients and water requirements of irrigated wheat (Triticum aestivum L.) in the Nigerian savannah zone

Abstract

Daily water use of irrigated wheat (Triticum aestivum L., var. ‘Siete Cerros’) was determined for three seasons between 1983 and 1986 using a hydraulic weighing lysimeter at Kadawa in the Kano River Irrigation Project of Kano State, Nigeria. Crop coefficients were determined for various time intervals during each growing season using the lysimeter data and a grass-based reference crop evapotranspiration estimated with Class A pan evaporation data. Mean crop coefficients for each ten-day period of crop growth were then determined. Observed length of a season ranges between 110 and 120 days. Seasonal crop water use ranges between 395 mm and 456 mm. Wheat crop water requirements (CWR) were then estimated for major irrigation projects in the Nigerian Sudan and Sahel savannah zones, between latitudes 10°N and 14°N, using the crop coefficients obtained and long term mean climatic data. The estimated CWR agreed with values obtained from the lysimeter experiments. Seasonal CWR values estimated by designers of three existing irrigation projects in the area agreed with the experimental results, but the designers' short term, ten-day period estimates differed from the results obtained.