Suppression of soil nitrification by plants

Nitrification, the biological oxidation of ammonium to nitrate, weakens the soil?s ability to retain N andfacilitates N-losses from production agriculture through nitrate-leaching and denitrification. This processhas a profound influence on what form of mineral-N is absorbed, used by plants, and retained in the soil,or lost to the environment, which in turn affects N-cycling, N-use efficiency (NUE) and ecosystem healthand services. As reactive-N is often the most limiting in natural ecosystems, plants have acquired a rangeof mechanisms that suppress soil-nitrifier activity to limit N-losses via N-leaching and denitrification.Plants? ability to produce and release nitrification inhibitors from roots and suppress soil-nitrifier activityis termed ?biological nitrification inhibition? (BNI). With recent developments in methodology for insitumeasurement of nitrification inhibition, it is now possible to characterize BNI function in plants.This review assesses the current status of our understanding of the production and release of biologicalnitrification inhibitors (BNIs) and their potential in improving NUE in agriculture. A suite of genetic, soiland environmental factors regulate BNI activity in plants. BNI-function can be genetically exploited toimprove the BNI-capacity of major food- and feed-crops to develop next-generation production systemswith reduced nitrification and N2O emission rates to benefit both agriculture and the environment. Thefeasibility of such an approach is discussed based on the progresses made