The advantages of multi-cluster structure in city planning: From nutrient flow balance and environmental protection perspective – Take Beijing for example

As the gathering places of various materials and energy flow, cities will be threatened by more environment pressures if these energy and nutrients gathered there were not efficiently disposed. Thus, based on the nutrient cycling principles using greater Beijing municipality as example, we calculated the nutrients supply from human and livestock excreta and crops, as well as nutrients holding capacity of cultivated land under the 15,000 kg grain per ha yield condition. The results showed that the nutrients that flow into Beijing is higher than outflow to cultivated land. We recommend organic farming development to fully utilize nutrients from human and livestock excreta, and indicated that we should also adapt multi-cluster urban structure to increase the interface between urban structure and rural farming, and ultimately increase the energy and nutrient exchange efficiency between the two. By adapting this structure, nutrients collected in urban areas could be recycled back to agricultural use, and then the pressure on the urban eco-system could be reduced and improved.

► We calculated the nutrients supply from human and livestock excreta and crops, as well as nutrients holding capacity of cultivated land under the 15,000 kg grain per ha yield condition.
► We think that crop nutrients uptake could be met by implementing organic agriculture that would eliminate nutrient accumulation from commercial fertilizer application.
► We recommend organic farming development, and indicated that we should also adapt multi-cluster urban structure to increase the interface between urban structure and rural farming.