PERFORMANCE EVALUATION OF CENTRE PIVOT IRRIGATION SYSTEM AT KUKOBILA NASIA FARMS LIMITED IN THE SAVELUGU MUNICIPALITY, NORTHERN REGION OF GHANA

Abstract

The study evaluated the performance of the centre pivot irrigation system at Kukobila Nasia Farms Limited in the Savelugu Municipality, Northern Region of Ghana using centre pivot performance indicators. Two centre pivot irrigation systems were evaluated using selected performance indicators, categorised into; field operations, financial level, environmental condition and production potential. The problems of the centre pivot system were also identified. Field measurements, questionnaire administration, laboratory analysis and literature review were carried out. The study revealed that, the average water application rate of the centre pivots including the outer end exceeded the average infiltration rates of soil with average water application rates of 118.52 mm/h and 242.96 mm/h for pivot one and two and infiltration rates of 61.32 mm/h and 105.14 mm/h respectively. The CU obtained from centre pivot one ranged from 80.3 - 86.9 % whereas pivot two had CU ranged from 75.6 −84.4 %. Similarly, the DU calculated from pivot one and two ranged from 60.2−68.5 % and 65.3−73.2 % respectively. DU increased as the speed of operation of the centre pivot increased as a general trend. The lower values recorded for pivot one at 170 m/h and 102 m/h operating speed levels and that of pivot two at 136 m/h operating speed were attributed to wind drift. The SC obtained from pivot one and two were above the lower acceptable limits and ranged from 1.46 – 1.66 and 1.37−1.53 respectively. Centre pivot one Ea ranged from 80.3 - 98 % except at 170 m/h operating speed which recorded Ea of 56 %. Similarly, pivot two recorded Ea ranged from 51 - 89 % with Ea from operating speed of 102 m/h and 43 m/h meeting SABI norms. The values of PELQ were low and unacceptable as they ranged from 35 - 73 % and 38 - 61 % for pivot one and two respectively. The actual operating pressure (100 kPa) of the centre pivots was lower than the designed pressure (103 kPa). The weighted average discharge of the centre pivot one was lower as it recorded a discharge of 20.17 l/s against 25.52 l/s for centre pivot two. Salinity and pH were observed with no problem in any of the irrigable land. From the study, it cost about GH¢ 23.00 to pump 1 Ml volume of water to one hectare of irrigable land and 1 Ml of water was required to produce 442 kg of grains. The problems identified were high cost of operation, wind distortions of sprinkling and standardisation of the centre pivot operating speed to match with crop water requirements. Above listed constraints were limiting factors to increased crop production. Both centre pivots required; installation of nozzles with larger wetted diameter to match water application with infiltration rates of soil, periodic cleaning and replacement of clogged and or worn out nozzles and standardisation of operating speed to match with crop water requirements.