1. Fate of 15N-labelled ammonium nitrate with or without the new nitrification inhibitor DMPSA in an irrigated maize crop.
- Author
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Guardia, Guillermo, Vallejo, Antonio, García-Marco, Sonia, Cardenas, Laura M., and Dixon, Elizabeth R.
- Subjects
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CORN , *AMMONIUM nitrate , *SOIL leaching , *LEACHING , *NITRIFICATION inhibitors , *NITRIFICATION , *PREVENTION - Abstract
Nitrification inhibitors, originally proposed for nitrate leaching mitigation, are recommended as effective nitrous oxide (N 2 O) mitigation strategies. Several compounds have been trialled and used in the past including dicyandiamide (DCD) or 3,4-dimethylpyrazole phosphate (DMPP). Yet, little is known about the new nitrification inhibitor 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA). A field experiment using 15 N single-labelled ammonium nitrate ( 15 NH 4 NO 3 or NH 4 15 NO 3 ) was conducted to understand the effectiveness of DMPSA on a biochemical basis in an irrigated maize ( Zea mays L.) crop. Gaseous fluxes, i.e. N 2 O, 15 N 2 O, 15 N 2 , methane (CH 4 ), and carbon dioxide (CO 2 ) were measured, as well as soil mineral N, yield components and 15 N recovery in plant and soil. During the maize cropping period, the use of DMPSA significantly reduced cumulative N 2 O emissions (118 g N ha −1 ) compared to ammonium nitrate without inhibitor (231 g N ha −1 ). The 15 N analyses revealed that most N 2 O losses (particularly during the emission peak) came from 15 NH 4 NO 3 (i.e. nitrification, nitrifier denitrification and/or coupled nitrification denitrification) rather than NH 4 15 NO 3 in this calcareous low C-content soil. As expected, DMPSA decreased N 2 O losses from 15 NH 4 + oxidation, but an effect on non-target microorganisms was noticed, as shown by the significant reduction of respiration rates and N 2 O losses coming from 15 NO 3 − . No significant effect of DMPSA on CH 4 oxidation or 15 N 2 fluxes was observed. The DMPSA did not lead to a significant improvement of the dry weights of grain or biomass, although an increment of root biomass by 64% was found. This compound also tended to increase plant N recovery (average 67.8%) and to decrease soil N recovery (average 18.3%) but differences were not statistically significant. Conversely, the nitrification inhibitor significantly reduced the residual fertilizer-N in the 15–30 cm and 30–45 cm soil layers. The use of DMPSA was confirmed as a highly effective tool to reduce N 2 O emissions from irrigated crops in semi-arid areas. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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