*4.3. Effects of Drip Irrigation on Water Productivity and Crop Yield*

A significant water saving was observed under the drip system (38% for potato and 33% for onion), mainly due to the capability of the drip system in delivering water uniformly to the root of crops and minimizing water losses. Drip irrigation systems reduce water application to open ground or soil spaces that are not directly used by crops, which would rather facilitate weed growth. The result suggests that the combined use of drip irrigation and CA provides a significant water use efficiency as compared to the combination of CA and overhead irrigation. Assefa et al. [16] found nearly a threefold water saving capacity when combined with CA as compared to overhead irrigation with the tilled system. This will help minimize the overexploitation of shallow groundwater wells and maximize irrigated crop production. A similar result was reported by Kigalu, et al. [61] which found a quadratic response of water productivity for the drip system as compared to overhead irrigation in Tanzania.

The effect of the drip irrigation system was significant in improving crop productivity as compared to overhead irrigation. Potato and onion yield was increased by 43% and 36%, respectively under drip irrigation. Dawit, et al. [62] reported similar results, improved crop yields for drip irrigation in the eastern part of Ethiopia. The uniform water application and minimum soil nutrient loss associated with the drip system would be the main reason for improved crop yield. Fandika, et al. [63] result indicated a higher tomato yield response associated with the uniform water application in the drip system. Whereas, Elhindi, et al. [64] and Mirjat, et al. [65] observed minimum loss of soil minerals, and fertilizers when using drip irrigation.

#### *4.4. Comparison of MajiPump with Previous Pulley Studies on Water Productivity*

Water productivity was significantly improved under MajiPump water-lifting system when compared with a pulley system [11,22,29] for the same crop types (Figure 7). The water productivity values of garlic, onion, and cabbage under the MajiPump with CA were 3.2 kg m−3, 9 kg m−3, and 20 kg m−3, respectively, while the corresponding values were 1.1 kg m−3, 2.6 kg m−3, and 9.2 kg m−<sup>3</sup> for the pulley system with CA (i.e., 190%, 246%, and 117% improvements, respectively). Besides, the MajiPump showed a significant water productivity improvement in the conventional tilled (CT) system. The water productivity of garlic, onion, and cabbage under MajiPump with CT was 1 kg m<sup>−</sup>3, 6.7 kg m−3, and 14.4 kg m−3, respectively, and 0.6 kg m−3, 0.2 kg m−3, and 6.9 kg m−<sup>3</sup> under the pulley with CT system (i.e., 67% to 325% higher than the pulley with CT system). Moreover, the water productivity under the MajiPump with CT was higher than the pulley system with CA. The water productivity under the MajiPump with CT was 6.7 kg m−<sup>3</sup> and 14.4 kg m−3, while it was 2.6 kg m−<sup>3</sup> and 9.2 kg m−<sup>3</sup> under the pulley system with CA, respectively, for onion and cabbage vegetables (i.e., 158% and 56% improvements, respectively).

**Figure 7.** Comparison of MajiPump and pulley system on water productivity.

In general, the highest water productivity benefit could be gained through the combined use of MajiPump with CA practice. The highest water productivity in the MajiPump system was attributed to its additional advantage to increasing labor productivity. Farmers in the study area explained that water-lifting using the MajiPump took 5 to 10 min while a pulley system took 1.5 to 2 h to fill a 1.5 m height elevated 500 L water storage tank. Besides, filling a water storage tank with the pulley system requires two persons at a time when the labor time in the MajiPump system is only to connect the pump and solar panel. The minimum labor demand in using the MajiPump initiated smallholder farmers to provide enough irrigation water for vegetables, and thus increasing their water and labor productivity.
