Reducing nitrogen impacts in northern Indian cropping systems: realising production and environmental benefits A growing world population requires a growing food supply. The rise in crop yields resulting mainly from the production and application of synthetic nitrogen (N) fertilizer together with the selection of N responsive varieties sustained population growth throughout the 20th century. However, N fertiliser use is of global concern because it is associated both with high levels of energy use and greenhouse gas emissions that cause climate change, in addition to damage to fresh water and marine ecosystems.   N fertilisation is required for achieving high yield in cereal crops including wheat and rice. Increasing sustainability through a decrease in N fertiliser inputs has to date proved difficult due to the resulting fall in productive yield, farmer income and staple food supply. In addition, the current status of policy (and associated subsidy) intervention in fertiliser pricing in India (and other parts of the developing world) supports high application rates to drive yields. This leads to numerous outcomes, many of which are unfavourable for long-term sustainability. In addition this N demand drives the continual growth of synthetic fertiliser production (shown right), an energy intensive process resulting in additional emission and energy costs.  Our work on the N challenge to date has delivered major impacts to both UK and Indian cereal cropping through development of a new framework for optimising N use (UK) and through a direct intervention in farming practice to reduce N use in farmers' fields in Bassian village (a colour-based method of determining optimal N rate called the PAU-LCC, India). We have provided important step changes in our understanding of the potential to reduce N fertiliser use without compromising productivity or economic returns to farmers.   This translational proposal builds on these outcomes to ensure that we realise their full value in terms of agricultural sustainability in India. We have established a solid foundational partnership with the social welfare NGO Atam Pargas and the farming community in Bassian village, which provides an important framework for focussing the delivery of impact and is a model for future system transformation in India. We will continue to base our work on this platform with the aim that all crop production in Bassian village makes use of the PAU-LCC for determining optimal N application. Additionally, this translational project will address two of the major gaps that we have identified based on our work to date. The first is a means to quantify and assess environmental benefits of reduced N fertiliser application at the local (village) scale allowing for the calculation of a full N budget to reflect the impact of simple interventions to reduce N use. The second is a framework for engaging in the Indian agricultural policy agenda around N reduction interventions. Agricultural policy in India is intricately linked to future agricultural sustainability and will largely determine how successful the practical interventions and monitoring in our project are so this framework will be crucial for realising the full impact of our work. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.