A comparison of the performance of Namibia-specific conservation and conventional tillage technologies as used for pearl millet production in northern Namibia

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University of Namibia
Studies were conducted over a period of three years (2011 to 2013) at the Ogongo Campus of the University of Namibia (UNAM), to compare the differences between tractors and animal-drawn implements both using conventional and Namibia Specific Conservation Tillage (NSCT) technologies. Two conventional tillage (CV) treatments (i.e. tractor-drawn disc harrow (TDH) and animal-drawn mouldboard plough (AMP) were compared to two NSCT treatments (tractor-drawn ripper furrower (TRF) and animal-drawn ripper furrower (ARF). There were four specific objectives. The first objective is to compare the field performances compare the field performances of the two technologies each for the NSCT and CV on (i) depth of cut, (ii) width of cut, (iii) draught of the power source (iv) efficiency and v) effective field capacity under Ogongo conditions. NSCT technologies (TRF and ARF) performed better than CV technologies (TDH and AMP) on depth of cut in all the three years. Though the NSCT technologies also resulted in higher draught forces than the CV technologies, however, the specific draught of NSCT technologies were better across the three seasons showing that they were more energy efficient than CV technologies. Tractor drawn tillage methods resulted in lower specific draught than animal-drawn tillage methods across the three years. ARF performed better than AMP in the last two years. None of the tractor-drawn implements in the study met the ASAE Standards of Efficiency (70-90%). The on-station field efficiencies fell short by 16% for TDH and by 8% for TRF. Across the three years, the effective field capacities for tractor-drawn tillage methods were: TDH = 0.68 ha hr-1, TRF = 0.74 ha hr-1. For animal-drawn tillage methods, the effective field capacities for AMP = 0.03 ha hr-1 and for ARF = 0.15 ha hr-1, 80% better than AMP.
A dissertation submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy in the Faculty of Engineering and Information Technology
Root length, Soil moisture, Conservation tillage