Skeptics of urban farming cite two main limitations. Because the longevity of these farming projects depends on the availability of the land for farming and the ongoing commitment of volunteers and low paid managers, the farms may be lost. Even in the nineteenth century interest tended to wane as the pressure of wartime or population growth passed. The second major criticism is related to scale. Given the infrastructure investment needed to begin a garden, such as soil preparation, water systems, tools, and so on, critics object that an urban farm is unable to feed enough people to be a cost-effective use of precious urban space. It may also be argued that the farms are exclusionary, even in poor neighborhoods, because they require membership or because higher quality produce may be more expensive or more seasonally limited. Indeed, many gardens are fenced and padlocked against vandalism and maintain lengthy waitlists for membership.