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Use of 1 H NMR to identify nitrogen and carbon metabolites associated with mineralizable N in grassland soil
Author(s) -
McDonald N. T.,
Graham S. F.,
Watson C. J.,
Gordon A.,
Lalor S. T. J.,
Laughlin R. J.,
Elliott C. T.,
Wall D. P.
Publication year - 2016
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12379
Subject(s) - chemistry , mineralization (soil science) , metabolite , nitrogen , environmental chemistry , citric acid , soil organic matter , soil water , glutamic acid , aspartic acid , nitrogen cycle , incubation , organic matter , soil chemistry , amino acid , biochemistry , organic chemistry , biology , ecology
Improved understanding of the metabolites linked to the mineralization processes of nitrogen ( N ) and carbon ( C ) in soil is important for optimum management, and to realize the soil's production potential to minimize associated environmental risks. A novel approach for investigating soil with proton nuclear magnetic resonance spectroscopy ( 1 H NMR ) was used to detect metabolites present in 35 contrasting grassland soil types in I reland. Soil samples were analysed for a range of chemical, biological and physical properties including mineralizable N ( MN ) with a 7‐day anaerobic incubation ( AI ‐7). We identified and quantified by multivariate and regression analyses seven soil metabolites related to MN , namely glucose, trimethylamine, glutamic acid, serine, aspartic acid, 4‐aminohippuric acid and citric acid. Glucose explained the largest percentage of the variation in MN ( R 2 = 0.72). The amino acids, aspartic acid, 4‐aminohippuric acid, glutamic acid and serine explained 39, 38, 27 and 19% of the variation in MN , respectively. These results suggest that a labile carbon source (seven possible metabolites) appears to be an important factor for soil microbial biomass ( SMB ) to regulate quantities of 7‐day mineralizable N from soil organic matter N ( SOM‐N ) pools in these grassland soils for potential plant uptake. The results also demonstrate the analytical ability of 1 H NMR as a potential practical platform to analyse the complex metabolite profiles in soil related to short‐term C and N mineralization. However, evaluation of 1 H NMR against other analytical techniques, such as high performance anion exchange chromatography and pulsed amperometric detection ( HPAEC‐PAD ), to profile soil metabolites is recommended. Highlights Knowledge of metabolites linked to C and N cycling in soil would help improve nutrient use efficiency. 1 H NMR was investigated as a novel approach for profiling metabolites in grassland soil. Seven soil metabolites that correlated with mineralizable N were identified. 1 H NMR is effective for simultaneous soil metabolite profiling, but spectral libraries need to be developed.