Repositioning fertilizer manufacturing subsidies for improving food security and reducing greenhouse gas emissions in China

China removed fertilizer manufacturing subsidies from 2015 to 2018 to bolster market-oriented reforms and foster environmentally sustainable practices.However,the impact of this policy reform on food security and the environment remains inadequately evaluated.Moreover,although green and low-carbon technologies offer environmental advantages,their widespread adoption is hindered by prohibitively high costs.This study analyzes the impact of removing fertilizer manufacturing subsidies and explores the potential feasibility of redirecting fertilizer manufacturing subsidies to invest in the diffusion of these technologies.Utilizing the China Agricultural University Agri-food Systems model,we analyzed the potential for achieving mutually beneficial outcomes regarding food security and environmental sustainability.The findings indicate that removing fertilizer manufacturing subsidies has reduced greenhouse gas(GHG)emissions from agricultural activities by 3.88 million metric tons,with minimal impact on food production.Redirecting fertilizer manufacturing subsidies to invest in green and low-carbon technologies,including slow and controlled-release fertilizer,organic-inorganic compound fertilizers,and machine deep placement of fertilizer,emerges as a strategy to concurrently curtail GHG emissions,ensure food security,and secure robust economic returns.Finally,we propose a comprehensive set of government interventions,including subsidies,field guidance,and improved extension systems,to promote the widespread adoption of these technologies.

Iron isotope fractionation during fenitization:a case study of carbonatite dykes from Bayan Obo,Inner Mongolia,China

As a powerful tracer in high-temperature geochemistry,Fe isotopes have been studied for their behaviour during fl uid exsolution and evolution related to felsic magma system,but that for carbonatite magma system remains unknown.Here we study the Fe isotope fractionation behaviour during fenitization–processes that widely occur associated with carbonatite or alkaline intrusions.Nine fenite/carbonatite samples from carbonatite dykes at Bayan Obo area are analyzed for their Fe isotope compositions as well as elemental compositions.Combined with previous reported carbonatite δ^(56)Fe data,the results show that carbonatites range from-0.35‰to 0.28‰,with an average of-0.10‰in δ^(56)Fe values,while fenites range from-0.17‰to 0.30‰,with an average of 0.11‰in δ^(56)Fe values.This indicates that fenitizing fl uids exsolved from carbonatite melts are enriched in heavier Fe isotopes.Such a Fe isotope fractionation trend is diff erent from that for fl uid exsolution from felsic magmatism.δ^(56)Fe values in fenites are negatively correlated with indicators of fenitization intensity such as(Na+K),Ti,Ba,Th,Nb,U or Pb abundances,likely refl ecting that Fe isotopes fractionate during the evolution of the fenitizing fl uids.Thus,Fe isotopes are a valuable tool for tracing fl uid exsolution and evolution relevant to carbonatite magmatism and related metal mineralization.