Nitrogen Management in Grazed Pasture Systems

Ruminant grazing systems deliver essential protein but generate significant reactive nitrogen outputs that influence soil fertility, water quality and greenhouse gas fluxes. Pasture nitrogen inputs stem from organic sources such as livestock excreta and from inorganic fertilisers. Effective management seeks to optimise nitrogen use efficiency, enhance pasture productivity and mitigate emissions of nitrous oxide and ammonia. Central considerations include the spatial heterogeneity of urine patches and dung pats, temporal patterns of excretion relative to plant uptake, and microbial processes governing nitrogen transformations. Practices such as targeted fertiliser application timing, incorporation of leguminous species and use of inhibitors can reduce surplus nitrogen in soil, curtail leaching risks and moderate greenhouse gas emissions. Integration of precision monitoring technologies and adaptive grazing regimes underpins a transition towards more sustainable pastoral systems that meet production goals while preserving environmental quality on a global scale.

Research from Nature Portfolio

Seminal field investigations have delineated the role of co-denitrification as a dominant pathway for dinitrogen emissions following urine deposition in grazed soils. Isotopic enrichment techniques revealed that co-denitrification contributed the majority of N₂ losses over extended monitoring periods, reshaping the understanding of nitrogen gas fluxes in pastoral landscapes. Further work has demonstrated that soil moisture exerts a critical control on the balance between co-denitrification and heterotrophic denitrification. Under near-saturation conditions, elevated nitrite concentrations stimulated higher proportions of co-denitrification, whereas denitrification pathways prevailed at lower moisture levels. These insights have emphasised the interplay between hydrological regime and microbial nitrogen cycling, informing strategies to manage soil drainage and minimise reactive nitrogen losses.

Nitrogen Management in Grazed Pasture Systems publication trend

The graph below shows the total number of articles in nitrogen management in grazed pasture systems across all publications each year (not limited to Nature Index journals).

Technical terms

Co-denitrification: A microbial process combining applied nitrogen compounds with soil organic nitrogen to produce N₂ gas, distinct from classic denitrification.

Nitrification inhibitor: A chemical agent applied to soil that slows the oxidation of ammonium to nitrate, reducing nitrate leaching and nitrous oxide emissions.

Urine patch: A concentrated zone of soil enriched by a livestock urination event, characterised by high levels of ammonium and potential hotspots for nitrogen transformations.

Nitrogen use efficiency (NUE): The proportion of nitrogen input that is taken up by plants or retained in productive sinks relative to total applied nitrogen.

References

1. Confirmation of co-denitrification in grazed grassland. Scientific Reports (2015).
2. Influence of soil moisture on codenitrification fluxes from a urea-affected pasture soil. Scientific Reports (2017).
3. Response of soil health indicators to dung, urine and mineral fertilizer application in temperate pastures. Journal of Environmental Management (2023).
4. Meta‐analysis of global livestock urine‐derived nitrous oxide emissions from agricultural soils. Global Change Biology (2020).