## 4 Discussion  
Evaluating the condition of irrigation infrastructure is essential because the condition reflects on the level of management and maintenance on the systems. Moreover, the condition often correlates with the performance of the systems. Irrigation system performance is generally evaluated using several parameters and/or indicators at a time [5; 17; 24; 25] because none of the performance parameters are individually conclusive. The authors [5] used distribution uniformity (_DU_), coefficient of uniformity (_CU_), emission uniformity (_EUI_), application efficiency (_AE_), and potential application efficiency of the lower quarter. The authors [24] used _CU_, delivery performance ratio, irrigation productivity, labour requirement, and water quality. The authors [25] used _CU_, _EUI_, and _DU_. The authors of [17] used a mix of indicators from [5; 24]. The choice of parameters depends on whether the assessment is focusing on technical or physical characteristics of the system, aim of assessment, components to be assessed, taste and experience of the evaluator(s), and many other considerations. Figure 4: Comparison of distribution uniformities for four Agri-parks in Gauteng province, namely Rooiwal, Soshanguve, Tarlton, and Westonaria. Despite no access to baseline data for all the four study sites, the condition assessment results suggest the systems had deteriorated significantly [23]. The condition indices (CIs) varied from 2.12 to 6.29 (Table 2). According to [23], the CIs of <3 for the Booster pump-Manifold at Soshanguve and Westonaria (Table 1) implied a need for immediate replacement because the components had deteriorated beyond meaningful repair. Most of the irrigation system components at the Agri-Parks had CIs between 4 and 6, which implied their use could only be allowed for the next 3-5 years with a reassessment to be performed within the same period. In addition, there is need for the Agri-Parks to plan for repairing the components in 5-10 years' time from the date of the current assessment. The components with CIs > 6, such as the Main pump-Tank components at Soshanguve and Tarlton, were in good condition at the time of the current assessment with clear signs of recent repair works. The recommendations on continued use with contingent plans for repairs are only valid in the absence of a sudden and drastic deterioration during the intervening period. For instance, thefts and vandalism of the system components can invalidate the recommendations. It is, therefore, important to note that the recommendations presented [23] depend on component material responses to the vagaries of the natural operating environments. It was surprising to observe that some components performed well despite their very poor condition as depicted by their CI values, and some performed not so well despite their good condition (compare Tables 2 and 3). For example, the Booster pump-Filter units at Soshanguve and Westonaria performed well with conveyance efficiencies (CEs) of 99 and 73%, respectively, despite the very low respective CIs of 2.73 and 2.12. This was indicative of the fact that sometimes patchwork repairs can be effective, especially in the smallholder systems where resources are limited. Rubber and plastic were evidently used to reduce water leaks from broken subcomponents at the Agri-Parks. However, the success of patchworks cannot be guaranteed as evidenced by the poor performance of the Booster pump-Filter unit at Westonaria. In contrast, the good condition of the Pump-Tank components at Soshanguve and Tarlton did not result in impressive water CEs, where the respective values were 86 and 83%. Nevertheless, Soshanguve still performed better in terms of water conveyance than Tarlton despite the poorer condition, which brings to fore the impact of good management skills and experience. Soshanguve is managed by an individual farmer who has hired a skilled labour force to operate the system daily, while the co-operative of more than five individuals at Tarlton is less-skilled.