Crop production management practices as a cause for low water productivity at Zanyokwe Irrigation Scheme

Abstract

Generally, smallholder irrigation schemes (SIS) in South Africa have performed poorly and have not delivered on their development objectives of increasing crop production and improving rural livelihoods. Limited knowledge of irrigated crop production among farmers has been identified as one of the constraints to improved crop productivity, but research that investigates the relationship between farmer practices and productivity is lacking. A monitoring study was therefore conducted at the Zanyokwe Irrigation Scheme (ZIS) in the Eastern Cape to identify cropping systems and management practices used by farmers and to determine how these were related to performance. Evidence from 2 case studies showed that water management limited crop productivity. Irrigation application and system efficiencies were below the norm and irrigation scheduling did not take crop type and growth stage into account. Monitoring of 20 farmers over a 3-yr period showed that cropping intensity averaged only 48% and that the yields of the 2 main summer crops, grain maize (Zea mays L.) and butternut (Cucurbita moschata) averaged only 2.4 and 6.0 t•ha-1 , respectively. In addition to poor water management, other main constraints to crop productivity were inadequate weed and fertiliser management and low plant populations. The results indicated that a lack of basic technical skills pertaining to irrigated crop production among farmers was a possible cause of inadequate management. In this regard, it is expected that farmers could benefit from 'back to basics' training programmes in the areas of crop and irrigation water management. Research needs to focus on labour-saving production technologies, establishing farm-specific fertiliser recommendations, the identification and use of affordable sources of nutrients, as well as strategies to improve plant population in maize by preventing bird damage to newly-planted stands.

Status of Underutilised Crops in South Africa: Opportunities for Developing Research Capacity

“…Regardless of agroecology, maize is the dominant crop produced and this is linked with its status as a staple [32]. Mixed and maize monoculture (Table 1) are the dominant cropping systems [33][34][35]. Within these cropping systems, food crops such as beans (Phaseolus vulgaris), sweet potato (Ipomoea batatas), pumpkin (Cucurbita pepo) and butternut (Cucurbita moschata) are also produced.…”

Smallholder irrigation schemes in South Africa: A review of knowledge generated by the Water Research Commission

“…The average yield of 2.4 t maize grain·ha -1 and 6 t butternut·ha -1 was less than 25% of the maximum economic yield achieved at Zanyokwe in on-farm experiments managed by researchers (Fanadzo et al, 2010). Even though experimental plots are easier to manage than field-scale plantings, these findings suggested that inadequate farm management rather than infrastructural constraints was the principal factor that limited crop productivity at Zanyokwe.…”

“…At Zanyokwe in the Eastern Cape, yield gap analysis of grain maize and butternut indicated that large gaps existed between yields achieved by farmers and those achieved with good management in researcher-managed, on-farm trials (Fanadzo et al, 2010). The average yield of 2.4 t maize grain·ha -1 and 6 t butternut·ha -1 was less than 25% of the maximum economic yield achieved at Zanyokwe in on-farm experiments managed by researchers (Fanadzo et al, 2010).…”

“…Transplanted maize could be grown at lower nitrogen rates to achieve similar yield potentials as direct-seeded maize (Fanadzo et al, 2009). The combination of reduced post-emergence herbicide dosages of atrazine and use of narrow-row plant spacing was shown to be an effective weed-management strategy for maize at Zanyokwe, where pre-plant weed control was identified as the most important factor affecting butternut yield (Fanadzo et al, 2010).…”

Performance of Smallholder Irrigation Schemes in the Vhembe District of South Africa

“…Generally, the conclusion of these studies has been that the contribution of smallholder irrigation schemes to social and economic development of irrigation communities has been far below expectations. (Bembridge & Sebotja, 1992;Bembridge, 1997;Bembridge, 2000;Machete et al, 2004;Tlou et al, 2006;Fanadzo et al, 2010). However, against a background of poor performance of smallholder irrigation schemes, few if any of the studies attempted to identify factors that appeared to contribute to differences in performance among these schemes.…”