A multi-indicator assessment of peri-urban agricultural production in Beijing, China

摘要

Urbanization has proceeded rapidly in China, bringing large-scale social, economic and environmental change to the strategically important peri-urban regions that surround expanding cities. In the Beijing Metropolitan Region, with an area of 16,411 km2, government policies have sought the development of multi-functional peri-urban agriculture, favoring the production of cash crops, and the area of vegetable, fruit and organically grown cereal production has increased, whereas the area under conventional cereal production has declined. In this study, six characteristic agricultural practices in the peri-urban zone were compared in terms of energy use efficiency, economic and environmental performance. A multi-dimensional index was also constructed to compare overall performance. Conventional cereal cropping of spring maize (AP1) and winter wheat-summer maize (AP2) had the lowest energy inputs, highest energy use efficiency, and a positive net energy balance. However, cash crops (greenhouse watermelon-tomato, open-field peach; AP3 and AP4) and organically produced crops (Chinese chestnut, millet; AP5 and AP6) achieved substantially higher economic returns per ha cultivated. Fruit and vegetable crops also achieved much higher yields than conventionally grown cereals. Organically produced crops, although higher in value, achieved lower yields. Product carbon footprints ranged from 0.53 to 6.1 kg CO2eq kg−1and were lowest for fruit and vegetables. Water consumption ranged from 0.1 L kg−1for Chinese chestnut to 435 L kg−1for the outputs of the winter wheat-summer maize rotation. When the various indicator results were combined using a multi-dimensional index, the ranking of the different peri-urban agricultural practices was AP6  AP5  AP3  AP1  AP4  AP2. These results demonstrate that the multiple functions of per-urban agriculture are not always complementary. However, the adjustment of peri-urban agricultural practices in the Beijing Metropolitan Region appears to be increasing overall benefits. Nevertheless, benchmarking against practices in other parts of China and the world, suggests that there is substantial scope for improvement of peri-urban agriculture in the Beijing Metropolitan Region, with excessive N fertilization identified as a major contributing factor for the performance gap. The development of peri-urban agriculture in Beijing, as elsewhere, has emphasized multi-functionality, providing local food supply, economic returns for local farmers, ecological functioning, along with amenity. Different agricultural practices provide these benefits in different ways. Assessments that address only a single aspect risk informing decisions that have adverse unintended consequences. Studies employing a variety of indicators across the social, economic and environmental dimensions are required if the potential benefits of peri-urban agriculture are to be realized.