As identified above, the agricultural sector performs a range of social and cultural functions in the dualistic Chinese economy, providing important positive externalities for society, but often at the cost of efficiency and negative externalities for the environment. The TH588 capacity of the cities for rural-urban migrants may be declining (Ni, 2013) and certainly when the economy fluctuates agriculture can help buffer the impact by providing at least basic food security and income to returning migrant workers. For example, many migrant workers went back to farming after the financial crisis in 2008 (Ni, 2013), taking advantage of the alternative social security mechanism provided by access to land and/or casual agricultural employment. The need for rural areas to provide at least minimum social security arrangements for migrant workers is reinforced by their living and working conditions in cities, and by their legal status. Migrants are a vulnerable population in urban areas because of low incomes (further reduced by remittances to family remaining in the home village), long working hours and poor housing conditions, often all provided by the informal sector (FORHEAD, 2014). Poor urban residents in neighbourhoods with limited social infrastructure are similarly vulnerable but migrant workers are particularly so, and also less likely to have access to medical and other social services, frequently living in more densely concentrated conditions in old or peripheral areas of cities with more limited access to drinking water, heating, waste disposal and other services (Holdaway, 2014).