Environmental effects and spatial inequalities of paddy field utilization are increasing in China

Understanding the spatiotemporal dynamics of the environmental effects associated with paddy field utilization (PFU) is imperative for safeguarding the availability of food while preserving the environment. While thorough investigations have been carried out on the individual environmental effects of PFU, study on comprehensive environmental effects of PFU and the spatial inequity issues stemming from the transfer of these effects are scarce. This study aims to quantify the greenhouse gas emissions (GHGE), nitrogen emissions (NE), and water consumption (WC) linked to PFU in China from 2000 to 2020. Additionally, it evaluates the transference of environmental effects through the inter-provincial rice flow and examines the resultant spatial inequity issues. The intensity of GHGE has demonstrated a consistent increase, while the intensity of NE has shown a fluctuating yet generally decreasing trend. Provinces with high water footprints are predominantly located in the northern regions. Specifically, GHGE increased by 3.54 Mt, primarily due to intensified agricultural inputs. NE decreased by 0.08 Mt, largely influenced by the enforcement of sustainable agricultural practices. WC escalated by 3.49 billion m³, chiefly as a result of heightened groundwater dependence. Significant increases in environmental effects were observed in Northeast China Plain (NECP) and Middle-lower Yangtze Plain (MLYP), whereas Yunnan-Guizhou Plateau (YGP), Southern China (SC), and Sichuan Basin and surrounding regions (SBSR) experienced reductions. The volume of inter-provincial rice flow initially surged before witnessing a decline, with a net increase of 15.59 Mt in rice outflow from NECP. The transferred volumes of GHGE, NE, and WC within China surged by 123.87%, 105.26%, and 119.05%, respectively. Huang-Huai-Hai Plain (HHHP) and SC emerged as principal outflows of environmental effects, while MLYP and NECP became the main inflows, exacerbating regional environmental disparities. Lorenz curves for GHGE, NE, and WC indicate a growing deviation from the line of absolute equality, highlighting a substantial increase in spatial inequality regarding the environmental effects of PFU in China. Moving forward, it is crucial to optimize PFU and rice flow patterns to mitigate the specific regional environmental effects, enhance the spatial efficiency of rice production, and promote spatial equity in environmental effects.