Nitrogen Dynamics in Paddy Soil Systems

Paddy soils are unique wetland systems in which nitrogen (N) transformations are governed by alternating oxic and anoxic conditions, root–microbe interactions and human management. Inputs of N include mineral fertilisers, biological fixation and organic amendments, while losses occur through denitrification, volatilisation and leaching. In flooded rice systems, ammonium (NH4⁺) is the dominant plant-available form, but nitrification to nitrate (NO3⁻) can create zones of nutrient heterogeneity and drive N₂O emissions. Rice roots release oxygen into the rhizosphere, creating micro‐oxic niches that foster nitrifying and denitrifying communities in close proximity. The balance between nitrification and denitrification controls N-use efficiency (NUE) and greenhouse gas production. Advances in sensor technologies, isotopic tracers and molecular tools have deepened our understanding of how redox dynamics, pH gradients and microbial community structure shape N availability. Improved management of fertiliser timing, form and placement, combined with the use of organic residues or biochar, offers pathways to enhance rice productivity while mitigating environmental impacts on a global scale.

Research from Nature Portfolio

Recent studies employing microscale analyses have revealed the fine-scale heterogeneity of ammonium and nitrate in the rooting zone of flooded rice soils. Using high-resolution microprofiling of pH, oxygen and inorganic N, researchers demonstrated that fertiliser application shifts redox boundaries and alters the spatial distribution of nitrification hotspots within millimetre-scale patches. Path‐analysis approaches identified pH in the water phase and solid matrix, followed by NH4⁺ concentration and dissolved oxygen, as key predictors of local nitrification rates. These insights into microscale biogeochemical controls inform precision-management strategies for N fertilisers and underscore the link between soil physical structure and nutrient-use efficiency in paddy systems.

Nitrogen Dynamics in Paddy Soil Systems publication trend

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

Technical terms

Nitrification: Microbial oxidation of NH4⁺ to NO2⁻ and then NO3⁻ under oxic conditions.

Denitrification: Microbial reduction of NO3⁻ to gaseous forms (NO, N₂O, N₂) under anoxic conditions.

Rhizosphere: Soil region directly influenced by root exudates, oxygen release and microbial activity.

Ammonium (NH4⁺): Cationic form of inorganic N prevalent in flooded soils and readily taken up by rice roots.

Nitrate (NO3⁻): Anionic form of inorganic N that can leach or undergo denitrification in wetland soils.

Nitrogen-use efficiency (NUE): Ratio of N taken up by the plant to N applied, reflecting the effectiveness of fertiliser use.

References

1. Microprofiling of nitrogen patches in paddy soil: Analysis of spatiotemporal nutrient heterogeneity at the microscale. Scientific Reports (2016).
2. The impact of replacing chemical nitrogen fertilizer with monosodium glutamate waste liquid residue on yield, quality, and carbon emission of rice production. Carbon Research (2024).
3. Rhizosphere soil nitrification ability controls nitrogen‐use efficiency in rice growth period. Food and Energy Security (2022).
4. New Insights into How Increases in Fertility Improve the Growth of Rice at the Seedling Stage in Red Soil Regions of Subtropical China. PLOS ONE (2014).