Water footprint assessment of maize and associated broiler production in South Africa
Nkhuoa, Phoka Gerald
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South Africa is a water-scarce country. Globally, the agricultural sector accounts for 75% of freshwater consumption, followed by the industrial sector with 20%, and the domestic sector with 5%. The human population is anticipated to increase by 2.3 billion people between 2009 and 2050. This will give rise to an increase in demand for food, fibre, and biofuel crops; consequently putting pressure on freshwater resources between the three economic sectors. Despite only 1.5% of South Africa’s agricultural land being under irrigation, irrigated agriculture uses about 60% of freshwater resources. The contribution of agricultural irrigation to achieve food security is seen in how it contributes to 30% of grain production. Irrigation allows farmers to harvest relatively higher yields per hectare (ha) compared to rain-fed conditions. Greater yields entail more labour requirements and thus employment opportunities. It also results in higher farm revenues. The increase in the demand for freshwater will force economic sectors to compete for freshwater. Given the high level of water use seen in the agricultural sector as well as the dependence of the agricultural sector on freshwater, there is more potential for reducing water demand in the agricultural sector and great benefits from informing water users and policy makers of sustainable water use management in the agricultural sector. Maize is an important crop in South Africa, which is both imported and exported, with South Africa being a net exporter of maize. Furthermore, it is a major ingredient in broiler feed as it makes up more than 60% of broiler feed. Given the pressure to use freshwater in a sustainable manner to ensure the indefinite production of irrigated crops, a water footprint assessment (WFA) may be used as a sustainability indicator to identify whether production is sustainable. A water footprint is the volume of water used to directly and indirectly produce a product or service. It comprises three components, namely the green, blue, and grey water footprints. Internationally, a large amount of work has been published on WFAs for field crops by authors such as Aldaya and Hoekstra, (2010), Sun et al. (2013), Chapagain and Orr (2010), Hoekstra et al. (2011), and Mekonnen and Hoekstra (2010). However, very few applications have been conducted locally. These include the work of SABMiller, the World Wide Fund For Nature (WWF), Pegasys Consultants (2010), Pahlow, Snowball and Fraser (2015), Munro et al. (2015), and Scheepers (2015). The volume of scientific research is therefore insufficient to effectively guide the management of local water resources. The aim of this study was to assess the water footprint of maize and broilers as derived from irrigated maize production in the form of a case study carried out in the Bloemfontein area. This aim was attained by firstly quantifying the volumetric water footprint indicators for the production of maize and broilers as derived from maize production. Thereafter a sustainability assessment was conducted, followed by the formulation of response strategies to inform the sustainable use of freshwater. The method of the Water Footprint Network (WFN) was identified as suitable to achieve the aim and objectives of this study. The method consists of the scope of the study, water footprint accounting, sustainability assessment, and response formulation. Maize water use data were obtained from secondary data from experiments conducted by Van Rensburg et al. (2012), who collected data from the Orange-Riet Irrigation Scheme. Water use data for farm-level broiler production were obtained from a broiler-producing company. Process data were obtained from a broiler-processing company, which happened to be the same firm that produces broilers on site. At a yield level of 14.32 tonne/ha, the total maize water footprint was determined as 584.19 m3/tonne. This comprises a green water footprint of 186.92 m3/tonne, a blue water footprint of 275.58 m3/tonne, and a grey water footprint of 121.69 m3/tonne. The total broiler water footprint was detetermined as 1 474.56 m3/tonne of chicken meat produced. The water footprint of farm-level broiler production, excluding feed, is equivalent to 38.82 m3/tonne, while the water footprint associated with broiler feed was 1 430.33 m3/tonne. The slaughtering and processing of the broiler chickens used 2.70 m3/tonne each. The economic water productivity (EWP) was found to be higher for fresh chickens than for frozen chickens. Chicken portions had a higher associated EWP than whole chickens. Maize and broiler production were found to be sustainable from December to May. It is recommended that maize production in the Orange-Riet Irrigation Scheme should commence from December rather than October. Irrigation should be postponed to the later hours of the day. Optimum in-row spacing should be implemented to provide sufficient covering of the ground surface to avoid evaporation losses from the soil.