Optimizing nitrogen management in the food system for sustainable development: a case study of Quzhou County

Nitrogen(N) is an essential nutrient for food production. The rapid increase in population requires high inputs of N to meet the growing food demand. If not managed well, the substantial loss of N from the food system has multiple impacts on grain yield, air and water pollution, and the economic benefits of agricultural. Multi-objective(food security, environmental sustainability and economic sustainability) synergistic consideration of N management in the food system is still lacking. This study employed strategies for optimizing N management in the food system, using Quzhou County as a typical example on the North China Plain. Firstly, a food chain approach was adopted to understand drivers and reasons behind N losses from the food system.Secondly, a top-down approach was used to define multi-objective N management, taking into consideration food security, environmental sustainability and economic sustainability. Multi-objective N management aims to reduce N losses to the environment and increase N use efficiencies,while simultaneously increasing yields and economic benefits. Thirdly, 3R(reduce-retain-recycle) N management strategies were identified for specific crops and animals through a bottom-up approach and then analyzed the potential of these strategies to achieve the multi-objectives. Finally, there is a discussion of how to engage different stakeholders to promote the technologies implementation. This study provides new insights into the synergistic achievement of multi-objective N management in the food system and the development of environmentally-friendly agriculture.

WATER POLLUTION AND AGRICULTURE:MULTI-POLLUTANT PERSPECTIVES

Agriculture is an important cause of multiple pollutants in water.With population growth and increasing food demand,more nutrients,plastics,pesticides,pathogens and antibiotics are expected to enter water systems in the 21st century.As a result,water science has been shifting from singlepollutant to multi-pollutant perspectives for large-scale water quality assessments.This perspective paper summarizes and discusses four main highlights related to water pollution and agriculture from the multi-pollutant perspective.These highlights reveal the spatial and temporal distribution and main sources of multiple pollutants in waters.Based on the highlights,a scientific agenda is proposed to prioritize solutions for sustainable agriculture(UN Sustainable Development Goal 2)and clean water(UN Sustainable Development Goals 6 and 14).This agenda points out that when formulating solutions for water pollution,it is essential to take into account multiple pollutants and their interactions beyond biogeochemistry.

Innovations of phosphorus sustainability:implications for the whole chain

Phosphorus(P)is a non-renewable resource,therefore ensuring global food and environmental security depends upon sustainable P management.To achieve this goal,sustainable P management in the upstream and downstream sectors of agriculture from mineral extraction to food consumption must be addressed systematically.The innovation and feasibility of P sustainability are highlighted from the perspective of the whole P-based chain,including the mining and processing of P rock,production of P fertilizers,soil and rhizosphere processes involving P,absorption and utilization of P by plants,P in livestock production,as well as flow and management of P at the catchment scale.The paper also emphasizes the importance of recycling P and the current challenges of P recovery.Finally,sustainable solutions of holistic P management are proposed from the perspective of technology improvement with policy support.