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Cropping Pattern and Crop-Water Productivity Assessment in Mizawa Watershed, Blue Nile Basin, North Western Ethiopia

Nurelegn Garede, Teklu Erkosa

The big problem that challenges agricultural production is to produce more food from less water. Information on crop water in productivity Mizawa micro watershed was not available to conduct water conservation practices without losing productivity levels of crops. To fulfill these gaps the study was designed to assess crop water productivity of major crops. CROPWAT model version 8.0 (2009) was used to compute the crop water requirement for each crop. In order to produce cropping pattern map of the study watershed, track points of boundaries of each crop fields and other land use classes were recorded using a hand held GPS. The collected track points were transferred to ArcMap directly from GPS using DNR Garmin software and changed to shape file (polygon). The weather data obtained from the weather stations was input into the FAO CROPWAT model was used to generate the crop water requirements and crop water use (actual evapotranspiration) for each crop in the cropping seasons. Water productivity was calculated for each crop after the average productivity of each sampled crop types were determined in kg/ha from the sampled crop using excel. Crop water use of the three major crops in Mizawa watershed was 456, 317 and 304 for maize, finger millet and tef respectively. In the 2011 cropping season the average the crop water productivity of rainfall of maize, finger millet and tef which was 0.014 kg/m3, 0.008 kg/m3 and 0.006 kg/m³ in respectively. Crop water productivity results by this study fall in the lower ranges of other studies. This might be because the in the monitoring sites fertilizer application and use of improved varieties was not practiced in the monitored sites. The crops got deficit especially in the mid of the growing seasons which exists in large parts of the watershed, as well as excess water and flooding as a result of high rainfall and low effective rainfall amount was observed in the development stages of the three crops under investigation showing management practices are the key to sustain high efficiency.