Livestock plays a crucial role in food and nutrition security. However, livestock production accounts for 0.18 of global greenhouse gas emissions. India has one of the highest livestock densities globally, mainly produced under traditional systems. Specifically, the emission and particularly nitrogen losses from cattle in traditional systems cannot be ignored. Nitrogen emission is substantial when cattle roam free and waste is not collected or managed efficiently. This paper reviews the literature to piece together the available information on nitrogen emissions from cattle in India to synthesize the evidence, identify gaps and contribute to further understanding of the problem. At the same time, the paper highlights the solutions to reduce nitrogen pollution from cattle production in India. The main findings are that most cattle in India are not reared to provide meat protein. The implication is that reactive nitrogen per capita consumption is lower than most developed countries. However, there are substantial inefficiencies in feed conversion, feed nitrogen use and manure management in India. As a result, nitrogen losses and wastage are considerable in the different production systems. Furthermore, the review suggests that social, cultural and economic factors such as convergent social behaviour, urbanization, regulations, changing consumption patterns, the demand for cheap fuel sources, culture and religion influence the production systems and, consequently, the emissions from livestock. Suggested solutions to reduce nitrogen pollution from cattle production in India are improving livestock productivity, adopting better feeding, manure and pasture management practices and using behavioural nudges.

This article describes the nitrogen flows in the environment and points to the specificities of the livestock production. Till the beginning of the 20th century, the symbiotic fixation and the recycling of animal excreta supplied the nitrogen necessary for the fertility of soil. In 1913, the Haber-Bosch process allowed the industrial synthesis of ammonia and made possible the fertilisation without association of crop production with the livestock farming. The efficiency of the nitrogen in livestock farming is low with nearly half or more of the inputs losses to the environment. These losses have diverse impacts that intervene at various spatial scales owing to the nitrogen cascade. Quantitative assessment of nitrogen flows at the scale of regions started in the early 1980s in Western Europe and North America. These studies provided estimates of the spatial variability of nitrogen discharge within a region. They confirmed the differences between areas with a high animal density such as Brittany (western region, France) and other regions. It was also found that the same nitrogenous losses could lead to different levels of environmental impacts according to the sensibility of a given environment and its capacity to cope with nitrogen excess. Climate, soils characteristics, animal density, and proportions of agricultural land under annual and perennial crops are drivers of this sensibility.