An environmental assessment of hydroponic farming in the Johannesburg Metropolitan area and potential for the Vaalharts region

MSc in Environmental Sciences, North-West University, Potchefstoom Campus

The Johannesburg inner city, through various intervention strategies to improve local food security and create a reliable model for small-scale vegetable production, has introduced innovative agricultural initiatives on its skyscrapers such as rooftop gardening, which have then evolved into hydroponic farming. These initiatives have been geared towards attaining local food security goals within the limited land spaces in the inner city, while also addressing unemployment and revitalising abandoned infrastructure (Cilliers et al., 2020). Soil-less vegetable farming is increasingly becoming recognised as one of the promising solutions to attain land and water resource use efficiency goals in areas with limited arable land, with a view to transforming vegetable production. The hydroponic initiatives in the inner city aim to create food system conditions that can improve household food security and nutrition, while optimizing significant input resources such as limited land and water. They have placed a focus on inner city areas where traditional farming has little potential and aspire towards implementation in other agriculturally intense areas such as the Taung area in the Vaalharts Valley, within the Northern Cape province. Taung experiences challenges with the productive use of land for conventional vegetable production because of irrigation water supply challenges. Practically, the implementation of hydroponic innovations is still new in South Africa, and resource use efficiency, particularly for important resources such as land and water, is understudied. This study assessed the physical environmental impacts (particularly land and water resource use efficiency) of hydroponic farming for its performance in the Johannesburg inner city area and the potential for implementation thereof in the Vaalharts Valley. Open-ended discussion interviews guided by interviewer-administered questionnaires as well as field visits were conducted to obtain the knowledge and perceptions of farmers and a few local water and agricultural land use authorities. According to the study results, 80% of the hydroponic farmers expressed the opinion that the practice was driven by the need to optimise the use of limited land within the densely built-up area, while using less water resources for vegetable production, whereas the other 20% was strictly looking to trial alternatives to conventional vegetable farming. 60% of the hydroponic farmers had land spaces between 300-352 square metres (sqm), of which the largest land parcel (352sqm) grew about 17800 plants whilst the other 40% had land sizes between 18-24 square metres, with the largest land parcel (24sqm) growing 400 plants. Hydroponic farmers utilised Dutch Bucket and Nutrient Film Technique (NFT) irrigation systems, of which 80% utilising NFT reported low water use, with one record of 20 litres of water every four days to irrigate 400 plants (24sqm). Thus, hydroponic farmers attributed the efficiency of hydroponic farming to requiring little land space and water quantities to produce a higher number of vegetable heads per square meter. With more financial, technical, and knowledge support as well as collaboration from various stakeholders, hydroponics could become a potentially successful strategy to ease conventional vegetable farming challenges in the Taung area. Taung farmers had land parcels between 0,42ha and 48ha; however, 80% of these were not successfully productive owing to irrigation water supply and access challenges as well as limited farming skills (only 33% had formal agricultural training). Therefore, hydroponics may present a promising solution to optimise use of limited available irrigation water in Taung. However, prior to its implementation, community-based small-scale initiatives to teach and/or expose farmers and community members (80% of community interviewees had no knowledge of vegetable farming practices) to basic practices and innovation in vegetable production are necessary to improve production skills, adoption levels and ensure successful implementation. Ultimately, promotion and support for hydroponic techniques should be given proper attention in South Africa if farmers are to maximize yield per square meter and water resources, while enhancing economic viability and productivity.

Masters