Biological Nitrification Inhibition in Soil Systems

Biological nitrification inhibition (BNI) is the capacity of certain plant species to secrete or release metabolites from roots or through residue turnover that selectively suppress soil nitrifying microorganisms. By targeting ammonia-oxidising archaea and bacteria, BNI slows the oxidation of ammonium to nitrate, thereby reducing nitrate leaching, nitrous oxide emissions and loss of applied nitrogen fertiliser. This mechanism underpins enhanced nitrogen use efficiency, improved soil health and climate-smart agriculture. Research to date has identified a diversity of hydrophobic and hydrophilic inhibitors, elucidated their chemical structures and quantified their effects in both tropical grasslands and major cereal systems. Progress in understanding the genetic control of BNI traits and the residual impact of BNI on subsequent crops highlights the potential to integrate this natural process into breeding programmes and pasture management, offering a sustainable approach to global nitrogen stewardship.

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Biological Nitrification Inhibition in Soil Systems publication trend

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

Technical terms

Biological nitrification inhibition: The release of natural compounds by plant roots or residues that suppress the activity of soil nitrifying microorganisms.

Nitrification: The microbial oxidation of ammonium (NH4+) to nitrate (NO3–) via nitrite, mediated by ammonia-oxidising archaea and bacteria.

Ammonia-oxidising archaea (AOA): A group of soil archaea that convert ammonia to nitrite as the first step of nitrification, often dominant in acidic soils.

Ammonia-oxidising bacteria (AOB): Bacteria that perform the initial oxidation of ammonia to nitrite, contributing alongside archaea to nitrification.

Root exudates: A complex mixture of organic compounds secreted by plant roots into the rhizosphere, including BNI compounds that interact with soil microbes.

Nitrous oxide (N2O): A potent greenhouse gas produced as a by-product of nitrification and denitrification processes in soil.

References

1. Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution. Proceedings of the National Academy of Sciences of the United States of America (2021).
2. Biological nitrification inhibition in maize—isolation and identification of hydrophobic inhibitors from root exudates. Biology and Fertility of Soils (2021).
3. Residual effect of BNI by Brachiaria humidicola pasture on nitrogen recovery and grain yield of subsequent maize. Plant and Soil (2017).
4. Improved Nitrogen Use Efficiency and Greenhouse Gas Emissions in Agricultural Soils as Producers of Biological Nitrification Inhibitors. Frontiers in Plant Science (2022).