Up-scaling of rainwater harvesting for crop production in the communal lands of the Modder River basin in South Africa: comparing upstream and downstream scenarios

Published ArticleThe study area is the Upper and Middle Modder River basin situated in a semi-arid area of central South Africa. This is an important catchment because of the relatively large nearby towns of Bloemfontein, Botshabelo and Thaba Nchu. Crop production in the basin using conventional production techniques is currently not suitable due to marginal and erratic rainfall, and high evaporative demand, as well as low precipitation use efficiency on the clay and duplex soils caused by large runoff and evaporation losses. A labour-intensive in-field rain-water harvesting (IRWH) technique for crop production recently introduced into a part of the basin occupied by communal farmers has been shown to increase maize and sunflower yields by 30 to 50% compared to conventional tillage, making crop production utilising this technique a feasible proposition for these farmers. The area of land suitable for the IRWH in the basin is estimated to be 80 667 ha, of which 15 000 ha is located in the communal land. The two catchment management options compared in this paper are: • Allowing the 80 667 ha to remain under grassland and utilising the runoff downstream for irrigating maize • Utilising the 80 667 ha for maize production in the basin using the IRWH technique. Results showed that the expected maize production from the options shown above were 23 040t and 137 134t respectively. The large unproductive water losses during storage and conveyance to downstream use points are probably the main reason for this large difference in production. An economic analysis, which enabled the grazing benefit to be included in the first option, shows that the gross margin of this option, expressed as R/m3 of rain water utilized, could be expected to be between 0.0234 to 0.0254 under current conditions, of which irrigation contributed about 25% or less. The comparable value for the IRWH option was 0.0354. The second option is clearly shown to be the most preferable, with high socio-economic benefits for the communal farmers who are currently struggling to achieve sustainable livelihoods

Assessment of the potential adoption of infield rainwater harvesting technique in the communal farming areas of the upper and middle Modder River Basin, South Africa

River basin is a geographical unit that defines an area where various users of the basin's water interact. In a river basin there are many water-related human interventions that modify the natural systems and impact on those who live downstream. Researchers from the Agricultural Research Council's Institute for Soil, Climate and Water (ISCW) have developed an infield rainwater harvesting (IRWH) technique for small-scale farmers in the Modder River basin. This technique increased crop yield significantly compared to conventional practices. Since the start of its dissemination by the ISCW programme, adoption at a homestead level grew from six to more than 950 households. The suitable land for the IRWH in the study area is estimated to be 80 667 hectares, of which approximately 14 500 hectares are in the communal farming area. If all the suitable areas were to be put under IRWH practice, a decrease in the runoff could be expected, with consequences on downstream water users. A field survey conducted using a participatory methodology on a sample of 21 villages selected randomly, revealed that there are strong positive motivators, such as increase in crop yield and more food available for the household which explain the rapid expansion of IRWH in homestead application. However, some very strong demotivators were identified, such as high levels of poverty, limited family labour for the preparation of the plots, lack of tools, and the lack of fences around community gardens which could lead to theft and damage by animals. It appears that the demotivators identified are strong enough to prevent a significant expansion of the IRWH technique beyond homestead scale. Hence the expected impact on water availability for downstream users is expected to be minimal. Keywords: adoption, infield rainwater, harvesting technique, communal farming South African Journal of Agricultural Extension Vol. 34(2) 2005: 334-34

Catchment management in semi-arid area of central South Africa: Strategy for improving water productivity

Published ArticleIn the semi-arid part of central South Africa, population growth and industrial development are the driving forces for an increased demand for water. This accentuates the need for wise decisions by catchment management agencies (CMAs), especially in water scarce semi-arid areas. These decisions become more and more complex as the range of demands widens over the spectrum of water consumers, i.e. municipal, industrial, irrigation and rainfed farming. A study was conducted in the Upper Modder River catchment which is situated in the semi-arid area of central South Africa, where crop production in the catchment using conventional production technique is currently not suitable due to marginal and erratic rainfall. Moreover, the area is characterised by low precipitation use efficiency as a result of large runoff and evaporation losses on clay and duplex soils. A labour intensive in-field rainwater harvesting (IRWH) technique recently introduced into a part of the basin occupied by small scale farmers has been shown to increase maize and sunflower yields by 30 to 50% compared to conventional tillage, making it a feasible option for the these farmers in the catchment. The area of land suitable for the IRWH located in the communal land is estimated to be 23 000 ha. Two catchment management options presented in this paper are: option-1: allowing the IRWH suitable land in the communal farming area to remain under grassland and utilizing the runoff downstream for irrigating maize; option-2: utilizing the IRWH suitable land for maize production in the basin, using the IRWH technique. Results showed that the expected maize production from option-2 was higher than from option-1. A financial analysis also showed that gross margin, expressed as Rand per m3 of rainwater utilized, was between 0.0234 to 0.0254 under option-1 and 0.0354 for option-2. This clearly shows that use of rainwater where it falls has high socio-economic benefits for the communal farmers who are currently struggling to achieve sustainable livelihoods

Catchment management in semi-arid area of central South Africa: Strategy for improving water productivity

In the semi-arid part of central South Africa, population growth and industrial development are the driving forces for an increased demand for water. This accentuates the need for wise decisions by catchment management agencies (CMAs), especially in water-scarce semi-arid areas. These decisions become more and more complex as the range of demands widens over the spectrum of water consumers, i.e. municipal, industrial, irrigation and rain-fed farming. A study was conducted in the Upper Modder River catchment, which is situated in the semi-arid area of central South Africa, where crop production in the catchment using conventional production technique is currently not suitable due to marginal and erratic rainfall. Moreover, the area is characterised by low precipitation use efficiency because of large runoff and evaporation losses on clay and duplex soils. A labour intensive in-field rainwater harvesting (IRWH) technique recently introduced into a part of the basin occupied by communal farmers has been shown to increase maize and sunflower yields by 30 to 50% compared to conventional tillage, making it a feasible option for the subsistence farmers in the catchment. The area of land suitable for the IRWH located in the communal land is estimated to be 23 000 ha. Two catchment management options presented in this paper are:• Option1: allowing the IRWH suitable land in the communal farming area to remain under grassland and utilising the runoff downstream for irrigating maize• Option 2: utilising the IRWH suitable land for maize production in the basin, using the IRWH techniqueResults showed that the expected maize production from Option 2 was higher than from Option 1. A financial analysis also showed that gross margin of option, expressed as R/ m3 of rainwater utilised, was estimated to be between 0.0234 to 0.0254 under Option 1 and 0.0354 for Option 2. This clearly shows that use of rainwater where it falls has high socio-economic benefits for the communal farmers who are currently struggling to achieve sustainable livelihoods

Conservation agriculture in Sub-Saharan Africa

Specific practices of conservation agriculture (CA) in sub-Saharan Africa are diverse and vary according to local farming conditions. However, despite more than two decades of investment in its development and dissemination, adoption of CA is low. Crop responses to CA are highly variable, and not always positive, which is an important hindrance for adoption, especially for resource-poor farmers who need immediate returns with their investments in CA in order to be able to feed their families. In contrast with commercial farms such as in Brazil, reduced costs with CA on smallholder farms in sub-Saharan Africa are not always observed. Another major challenge with the practice of CA is the use of crop residues for mulching since crop residues are a major source of feed for livestock, especially in semiarid regions, where biomass production is limited and livestock plays a crucial role in farming systems. Studies indicate that the three principles of CA, including mulching, are needed to increase crop yields compared with conventional tillage (CT)-based practices. Among the three principles of CA, mulching is certainly the one that is least observed in past and current cropping practices in Africa. CA has a potential to improve the soil water balance and increase soil fertility, and it is undoubtedly a cropping practice that can result in substantial benefits for certain farmers in Africa. The question is when and how it is the best approach for smallholder farmers in sub-Saharan Africa. In general, CA is more likely to be attractive for farmers with a strategy of intensification than for farmers who struggle to produce food for their family. The latter too often face multiple constraints that limit the possibilities to engage in technological innovations. Some farmers may not be interested in new technologies because they earn their income from off-farm activities. Good markets of input supply and sale of extra produce are a prerequisite condition for adoption of CA as they are for any other new agricultural technology that aims at intensification. In sub-Saharan Africa, there is certainly a need to better target CA to potential end users and adapt the CA practices to their local circumstances and specific farming contexts. (Résumé d'auteur