Here is a great blog with some good links. People use kitchen gardens either as a hobby, to feel some closeness with nature, to get some food that they are sure is free from chemicals, or generally to supplement their grocery purchases with some self-grown vegetables. This blog (link) talks more about self-sufficiency through the purpose of a garden.
As a result, you learn more about how to grow a garden more suited for growing more food (in these times of recession, would you rather have a garden with a large extent of green lawn, or the same space being used for growing vegetables? – a lawn might look more aesthetic, but a garden built on the process of self-sufficiency would be more useful). You read the whole research paper on this subject, built around efforts in Melbourne. Here are some extracts from the article:
Community food security has emerged as a key response to broader environmental and socio-political issues. This research paper explores an important aspect – the ability of community members in the metropolitan Melbourne area to grow their own food and beneficial herbs, plants of self-sufficiency or productive value, while practicing sustainable gardening methods.
The research found a large majority of respondents believed there were increasing community trends toward self sufficient gardening and sustainable gardening. The research findings discovered substantial evidence of diverse educational opportunities. It found confirmation on communal and individual benefits of self-sufficient gardening, and some setbacks to healthy growth in Melbourne’s gardens.