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Maintaining a balance between urban land (UL) expansion and urban population (UP) growth is one of the goals of sustainable development, and maintaining this balance requires more theoretical exploration and regional experience. This paper re-evaluated the imbalances in growth between urban land and urban population (IGULUP) from the perspective of allometric growth and explored its influencing mechanism, taking urban agglomerations (UAs) in China as a case. This paper reveals that the growth rate of UL in China is slightly higher than that of the UP. However, the IGULUP vary according to development stages. UAs in the primary stage and the early growth stage face the dilemma where UL grows faster than the UP. Conversely, for UAs in the later growth stage and the mature stage, the growth rate of the UP is higher than that of UL. Finally, an increase in economic development level, population agglomeration, fiscal expenditure, and urban compactness can help mitigate the gap between UL and UP. In contrast, industrial structure, urbanization level, and foreign direct investment may hinder the improvement of IGULUP by accelerating the rate of land expansion. These findings may make theoretical contributions to the formulation of more targeted land use control policies and urban population growth strategies. [ABSTRACT FROM AUTHOR]

Increased food production and consumption patterns have resulted in higher urban food phosphorus footprints, leading to a series of resource and environmental problems worldwide. We quantified the food phosphorus footprint of the African city of Kisumu using substance flow analysis. Our aim was to develop Kisumu's sustainable phosphorus management framework so that the city would reduce phosphorus losses into the food system. Our results show that in the year 2023, the import and export of food phosphorus in the Kisumu food system was 2730.26 ± 2.7% t P yr−1 and 3297.05 ± 2.4% t P yr−1, respectively. There was −566.79 ± −18% t P yr−1 food phosphorus deficit in the Kisumu food system. Crop planting subsystem runoff/leaching/erosion loss, household consumption subsystem waste loss, and pit latrine subsystem blackwater loss are the major pathways of phosphorus losses into the environment and the main contributors to the food phosphorus footprint in the city. The 2030 scenario analysis shows that implementing a comprehensive scenario scheme throughout the entire lifecycle process from phosphorus input to waste disposal is the best choice for reducing phosphorus losses and suppressing the growth of food phosphorus footprint in the future. Our study shows that the food phosphorus footprint in the Kisumu food system was 0.67 kg P cap−1yr−1 in 2023, which is still at a low level but may enter a continuous upward trend with the improvement of socio-economic development of the city. In our framework, we have proposed a few essential measures that include urine separation, installation of septic tank, adjustment of dietary structure, flexible layout of sanitary disposal facilities, and separation of organic waste streams to reduce food phosphorus footprints in Kisumu. Given the similarity of cities along the shores of Lake Victoria, our calculation methods and management strategies can be applied to other cities in the region. [ABSTRACT FROM AUTHOR]