What is a central idea in “Street Farmer”? Street Farmer The leading contributor to pollution in the environment is food and animal waste. The leading contributor to pollution in the environment is food and animal waste. Food and animal waste can be repurposed to benefit people and the environment. Food and animal waste can be repurposed to benefit people and the environment. Urban gardening has proven to be more productive than traditional farming. Urban gardening has proven to be more productive than traditional farming. The costs of urban gardening continue to outweigh the benefits.