Life-cycle phosphorus management of the crop production-consumption system in China, 1980-2012.

Phosphorus (P) is an essential resource for agriculture and also a pollutant capable of causing eutrophication. The possibility of a future P scarcity and the requirement to improve the environment quality necessitate P management to increase the efficiency of P use. This study applied a substance flow analysis (SFA) to implement a P management procedure in a crop production-consumption (PMCPC) system model. This model determined the life-cycle P use efficiency (PUE) of the crop production-consumption system in China during 1980-2012. The system includes six subsystems: fertilizer manufacturing, crop cultivation, crop processing, livestock breeding, rural consumption, and urban consumption. Based on this model, the P flows and PUEs of the subsystems were identified and quantified using data from official statistical databases, published literature, questionnaires, and interviews. The results showed that the total PUE of the crop production-consumption system in China was low, notably from 1980 to 2005, and increased from 7.23% in 1980 to 20.13% in 2012. Except for fertilizer manufacturing, the PUEs of the six subsystems were also low. The PUEs in the urban consumption subsystem and the crop cultivation subsystem were less than 40%. The PUEs of other subsystems, such as the rural consumption subsystem and the livestock breeding subsystem, were also low and even decreased during these years. Measures aimed to improve P management practices in China have been proposed such as balancing fertilization, disposing livestock excrement, adjusting livestock feed, changing the diet of residents, and raising the waste disposal level, etc. This study also discussed several limitations related with the model and data. Conducting additional related studies on other regions and combining the analysis of risks with opportunities may be necessary to develop effective management strategies.