Determination of Optimal Irrigation Scheduling for Potato (Solanum tuberosum L.) at Holeta, Centeral High Land of Ethiopia

Abstract

The knowledge of crop water requirement is an important practical consideration to improve water use efficiency in irrigated agriculture. Water use efficiency can be improved by proper irrigation scheduling, which is essentially governed by crop evapotranspiration (ETc).Therefore, this activity is aimed to evaluate the responses of crops to irrigation regime (when and how much) and to identify WP under optimal irrigation regime. Field experiment was conducted during 2013 and 2014 to determine the optimal irrigation regime of Potato (Local name: Belete) at Holeta Agricultural Research center under five irrigation treatments (Irrigation at -40% ASMDL, -20% ASMDL, ASMDL, +20% ASMDL and +40% ASMDL). For irrigation treatment at allowable soil moisture depletion (ASMDL), irrigation was scheduled when 30% of the total water available was depleted. Plant heights and tuber yield were measured and WP was calculated. Plant height and tuber yield did not vary significantly with irrigation treatments. But WP of -40% ASMDL resulted highly significant difference (P<0.01) in both consecutive years. Reducing the soil moisture depletion level by 40% from the recommended fraction (0.3) has significantly increased the water productivity. However, a significant yield reduction was not observed under this treatment. So it’s possible to conclude that applying 40% less from the ASMDL can be used for areas where water is a limiting factor. For areas where water is not a problem, using the FAo recommended ASMDL which is treatment 3 is recommended.

Keywords: Plant height, tuber yield, allowable soil moisture depletion level (ASMDL), irrigation regime, Water Productivity (WP).