Life cycle assessment of phosphorus use efficiency in crop production system of three crops in Chaohu Watershed, China

This study presented a life cycle assessment of the environmental impacts of the production of three crops (rice, wheat, and maize) in the Chaohu Watershed of China. The crop production system involved phosphate rock mining, P fertilizer manufacturing, crop cultivating, and crop processing. Resource depletion, climate change, and eutrophication were examined. The functional unit chosen was 1 ha of cultivated land. The results showed that phosphate rock mining and P fertilizer manufacturing had been the main contributors to P resource depletion, representing shares of 57.40% and 25.86%, respectively. Large quantities of extracted phosphate raw rock and manufactured fertilizer for heavy fertilizer application were identified as the main causes of these effects. Rice crop had depleted the largest share of P resources, as it required the highest level of fertilizer use. Crop cultivation and processing were found to be particularly influential in terms of climate change effects, representing shares of 45.37% and 41.70%, respectively. This had mainly result from high fertilizer and electricity use for crop cultivation and processing, respectively. When processing maize for flour production, higher levels of electricity producing greenhouse gases were consumed than those consumed for the other two crops. Moreover, crop cultivation accounted for 71.22% of eutrophication processes due to high degrees of fertilizer application even though all three crops exhibit nearly identical eutrophication potentials. In turn, means of mitigating such impacts to increase the phosphorus use efficiency of this system were presented. The limitations of this study must also be examined and studied in the future. (C) 2016 Elsevier Ltd. All rights reserved.