Suppression of soil nitrification by plants

Abstract

Nitrification, the biological oxidation of ammonium to nitrate, weakens the soil's ability to retain N and facilitates N-losses from production agriculture through nitrate-leaching and denitrification. This process has 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 health and services. As reactive-N is often the most limiting in natural ecosystems, plants have acquired a range of 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 activity is termed 'biological nitrification inhibition' (BNI). With recent developments in methodology for in-situ measurement 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 biological nitrification inhibitors (BNIs) and their potential in improving NUE in agriculture. A suite of genetic, soil and environmental factors regulate BNI activity in plants. BNI-function can be genetically exploited to improve the BNI-capacity of major food- and feed-crops to develop next-generation production systems with reduced nitrification and N2O emission rates to benefit both agriculture and the environment. The feasibility of such an approach is discussed based on the progresses made.

Biological nitrification inhibition by rice root exudates and its relationship with nitrogen‐use efficiency

“…Most of the synthetic inhibitors, such as nitrapyrin, DCD and DMPP, inhibit the Nitrosomonas genus by suppressing the AMO pathway, but have no effect on the HAO pathway. Some BNIs inhibit Nitrosomonas by blockage of both the AMO and HAO pathways (Subbarao et al, 2015). Others, such as methyl 3-(4hydroxyphenyl) propionate (Zakir et al, 2008), inhibit only the AMO pathway, as does 1,9-decanediol.…”

“…the very zones in which it is intended to inhibit nitrification (Cahalan et al, 2015). Given these constraints presented by synthetic inhibitors, it is necessary to develop plant-derived nitrification inhibitors, referred to either as natural nitrification inhibitors (NNIs) (Upadhyay et al, 2011) or biological nitrification inhibitors (BNIs) (Subbarao et al, 2015). These are easily available and environmentally friendly.…”

Biological inhibition of soil nitrification by forest tree species affects Nitrobacter populations

“…Evidence that some tree species can inhibit Nitrobacter Soils with low pH and low N availability, typical for most forest Hu et al, 2015), heathland (Bardon et al, 2018) and humid savanna ecosystems (Le Roux et al, 1995), harbour selected plants with diverse mechanisms for improving soil N availability (Chapman et al, 2006). In particular, it has been shown that some plant species in these ecosystems can inhibit nitrifiers (Lata et al, 2004;Subbarao et al, 2009;Srikanthasamy et al, 2018) and that this inhibition is due to the production of specific compounds, often by roots (Subbarao et al, 2006(Subbarao et al, , 2015Coskun et al, 2017). However, most plants previously identified as having a biological nitrification inhibition (BNI) capacity were grass species.…”

Can Incorporating Brassica Tissues into Soil Reduce Nitrification Rates and Nitrous Oxide Emissions?

“…This is termed biological nitrification inhibition (BNI), and there are many documented examples, particularly among tropical grasses (Subbarao et al, 2007). Nitrification is generally inhibited by the exudation of secondary metabolites from roots (Subbarao et al, 2015). However, changes in N transformation rates have also been observed after incorporation of crop tissues into soil; for example, brassica ( Brassica spp.)…”