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Impact of nitrogenous fertiliser-induced proton release on cultivated soils with contrasting carbonate contents: A column experiment

Gandois, Laure and Perrin, Anne-Sophie and Probst, Anne Impact of nitrogenous fertiliser-induced proton release on cultivated soils with contrasting carbonate contents: A column experiment. (2010) Geochimica et Cosmochimica Acta, vol. 75 (n°5). pp.1185-1198.

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Official URL: http://dx.doi.org/10.1016/j.gca.2010.11.025

Abstract

An experimental study was carried out in order to evaluate the impact of nitrogen fertiliser-induced acidification in carbonated soils. Undisturbed soil columns containing different carbonate content were sampled in the field. Fertiliser spreading was simulated by NH4Cl addition on top of the soil column. Soil solution composition (mainly nitrate and base cations) was studied at the soil column’s base. Nitrification occurred to a different extent depending on soil type. Higher nitrification rates were observed in calcareous soils. In all the soil types, strong correlations between leached base cation and nitrate concentrations were observed. Regression coefficients between base cations, nitrate and chloride were used to determine the dominant processes occurring following NH4Cl spreading. In non-carbonated soils, nitrogen nitrification induced base cation leaching and soil acidification. In carbonated soils, no change of soil pH was observed. However, fertilisers induced a huge cation leaching. Carbonate mineral weathering led to the release of base cations, which replenished the soil exchangeable complex. Carbonated mineral weathering buffered acidification. Since direct weathering might have occurred without atmospheric CO2 consumption, the use of nitrogen fertiliser on carbonated soil induces a change in the cation and carbon budgets. When the results of these experiments are extrapolated on a global scale to the surface of fertilised areas lying on carbonate, carbonated reactions with N fertilisers would imply an additional flux of 5.7 x 1012 mol yr -1 of Ca + Mg. The modifications of weathering reactions in cultivated catchments and the ability of nitrogen fertilisers to significantly modify the CO2 budget should be included in carbon global cycle assessment.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://dx.doi.org/10.1016/j.gca.2010.11.025
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
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Deposited By:Florence Amor

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