Resumen
Background: Agriculture relies on the intensive use of synthetic nitrogen (N) fertilizers to maximize crop yields,
which has led to the transformation of agricultural soils into high-nitrifying environments. Nevertheless, nitrifcation
inhibitors (NIs) have been developed to suppress soil-nitrifer activity and decrease N losses. The NIs 3,4-dimethyl‑
pyrazole phosphate (DMPP) and 2-(3,4-dimethy ...
[++]
Background: Agriculture relies on the intensive use of synthetic nitrogen (N) fertilizers to maximize crop yields,
which has led to the transformation of agricultural soils into high-nitrifying environments. Nevertheless, nitrifcation
inhibitors (NIs) have been developed to suppress soil-nitrifer activity and decrease N losses. The NIs 3,4-dimethyl‑
pyrazole phosphate (DMPP) and 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) are able to
reduce N2O emissions and maintain soil NH4
+ for a longer time. Although both NIs have been proven to be efective
to inhibit soil nitrifcation, their exact mode of action has not been confrmed. We aimed to provide novel insights to
further understand the mode of action of DMP-based NIs. We evaluated the performance of DMPP and DMPSA in soil
and pure cultures of nitrifying bacteria Nitrosomonas europaea.
Results: DMPSA did not inhibit nitrifcation in pure cultures of N. europaea. In the soil, we evidenced that DMPSA
needs to be broken into DMP to achieve the inhibition of nitrifcation, which is mediated by a soil biological process
that remains to be identifed. Moreover, both DMPP and DMPSA are thought to inhibit nitrifcation due to their ability
to chelate the Cu2+ cations that the ammonia monooxygenase enzyme (AMO) needs to carry on the frst step of
NH4
+ oxidation. However, the efciency of DMPP was not altered regardless the Cu2+ concentration in the medium.
In addition, we also showed that DMPP targets AMO but not hydroxylamine oxidoreductase enzyme (HAO).
Conclusions: The inability of DMPSA to inhibit nitrifcation in pure cultures together with the high efciency of
DMPP to inhibit nitrifcation even in presence of toxic Cu2+ concentration in the medium, suggest that the mode of
action of DMP-based NIs does not rely on their capacity as metal chelators. [--]
Materias
AMO,
Copper,
DMPP,
DMPSA,
Nitrification inhibitor,
Nitrosomonas europaea
Publicado en
Chemical and Biological Technologies in Agriculture 9 (56), 1-10 (2022)
Departamento
Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa. Institute for Multidisciplinary Research in Applied Biology - IMAB
Entidades Financiadoras
This project was funded by the Spanish Government (RTI2018-094623-B-C21 MCIU/AEI/FEDER, UE), by the Basque Government (IT-932-16), and by EuroChem Agro Iberia S.L.U. Dr. Adrián Bozal-Leorri held a grant from the Basque Government (PRE-2020-2-0142).