A participatory and practical irrigation scheduling in semiarid areas: the case of Gumselassa irrigation scheme in Northern Ethiopia

Abstract

Poor irrigation scheduling practices have been quoted as the major challenges for sustainability of small-scale irrigation schemes in Ethiopia due to complexity of scheduling techniques, cost and inaccessibility of soil-water monitoring tools, lack of various local climatic data and soil-water parameters. For local experts to easily schedule irrigation and to promote adoption by farmers, a cheap and simple computation procedure of irrigation scheduling is needed that considers local resources and opinions. So far, there is no such study in the context of Ethiopia. A simple irrigation scheduling method (Practical) was developed based on the FAO procedure (Brouwer et al., 1989), employing Hargreaves ET0 equation and the opinions of local farmers and extension agents. Then, the method was validated on-farm through participatory and close observation of farmers by comparing with CropWat simulated (Sophisticated) and local (Traditional) scheduling practices for 2015and 2015/16 irrigation seasons considering maize as indicator crop. Data on irrigation depths, yield and yield components and soil salinity were collected and analysed. Furthermore, a farmers’ day was arranged to collect opinions on the crop stand and scheduling techniques. In both irrigation seasons, the practical irrigation schedule method resulted in higher grain yield while saving substantial amount of water and in significantly higher water productivity (WP) compared to the other methods. Maximum (0.68 kg m−3 in 2015) and minimum (0.47 kg m−3 in 2015/16) WP were found in the practical and sophisticated approaches, respectively. The average root zone salinities among the alterative irrigation scheduling methods were not significantly different, in both irrigation seasons. Farmers’ and experts’ opinions were in favour of the practical scheduling method. The practical irrigation scheduling method is thus recommended for maize, around Gumselassa area. Further, the presented procedure can be adopted for preparation of irrigation calendars of other cops and in other regions.