Smallholder irrigation both for high value crops and forage is increasing in Amhara region. However, production remains below expectations due to inappropriate irrigation scheduling and its effect on nutrient uptake. The purpose of this study was to compare the irrigation amount applied for garlic and Napier grass and assess the effect of different irrigation treatments and crops on the soil nutrient depletion. The experiments were conducted during the dry season at Robit Bata, Ethiopia. Three different irrigation methods were compared for garlic: Time domain reflector (TDR), Crop water requirement (CWR) and farmer’s usual practice (FARMP) during a 140 day period. For Napier only the farmer practice treatment was available during a 135 day period. Data on crop production, water use, and fertilizer use and land management practices were collected. This resulted in one full season of garlic production and three seasons of Napier production (i.e. Napier was cut every 45 days). According to the field observations, the amount of water irrigated under garlic was 470 mm for TDR, 417 mm for CWR and 377 mm for FARMP. During the same period the FARMP treatment with Napier received only 180 mm. The estimated crop coefficient for garlic was estimated at 65, 105 and 140 days after planting which corresponded to 0.65 initial, 1.29 mid and 0.6 let stage of development. Similarly for Napier grass crop coefficient were estimated at 10, 25 and 45 days corresponding to 0.85, 0.96 and 1.27. Partial N balance found for garlic was 78.08Kg/ha for (TDR) 61.81Kg /ha for (CWR) and 129.84Kg /ha (FARMP) while the FARMP Napier only had 22kg/ha, Partial P balance found for garlic was-2.90Kg /ha for (TDR) -7.10Kg /ha for (CWR) and -4.97Kg /ha (FARMP) while the FARMP Napier only had -48.43Kg /ha and Partial K balance found for garlic was -96.135Kg /ha for (TDR) -93.397K/ha for (CWR) and -60.943 K/ha (FARMP) while the FARMP Napier only had -293.1 kg/ha. Comparing both crops under FARMP treatment showed that the nutrient balances for Napier grass were highly depleted. And comparing the different irrigation practices showed that the TDR treatment resulted in a good nutrients balance which corresponded to higher yields obtained in the treatment.