The best step to take next in your research project would be to:
Narrow down your search by including specific keywords related to food security and Johannesburg's inner-city neighbourhoods.
This approach allows you to focus your research on the specific aspects of urban agriculture that are relevant to your study, making it easier to find targeted information without getting overwhelmed by irrelevant data. It helps refine the search results to include only those articles that are pertinent to your specific research question.