1. Wetting-drying cycles do not increase organic carbon and nitrogen mineralization in soils with straw amendment
- Author
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Isabelle Bertrand, Martial Bernoux, Tiphaine Chevallier, Pierrot Lionel Yemadje, Hervé Guibert, Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Agroécologie et Intensification Durables des cultures annuelles (UPR AIDA), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), and C2D Cameroun Project
- Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences ,Crop residue ,010504 meteorology & atmospheric sciences ,MINERALISATION ,01 natural sciences ,STOCKAGE ,C-13 isotope ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Priming effect ,Périodicité ,2. Zero hunger ,chemistry.chemical_classification ,FERTILITE DU SOL ,Chemistry ,13C isotope ,food and beverages ,Soil chemistry ,Residues ,04 agricultural and veterinary sciences ,Straw ,CARBONE ,FACTEUR CLIMATIQUE ,Minéralisation du carbone ,Nitrogen ,Soil Science ,Wetting-drying cycles ,Saison sèche ,AZOTE ,Soil organic carbon mineralization ,Organic matter ,0105 earth and related environmental sciences ,Soil organic matter ,MATIERE ORGANIQUE ,P30 - Sciences et aménagement du sol ,Mineralization (soil science) ,15. Life on land ,Saison humide ,Agronomy ,13. Climate action ,Soil water ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Soil fertility ,Minéralisation de l'azote - Abstract
Increasing soil organic matter (SOM) is of primary importance for maintaining soil fertility and mitigating climate change. Leaving crop residues on top of soil is not always an efficient means of increasing SOM because (i) of the high mineralization of the crop residues, (ii) crop residues may increase the mineralization of existing SOM (priming effect) and (iii) wetting-drying cycles may increase mineralization of SOM and crop residues. Little research has been carried out into these mechanisms under Sudano-Sahelian conditions where the rainfall is mostly irregular with wetting-drying cycles during the transition between the wet and the dry season. To evaluate the effect of wetting-drying cycles on the mineralization of SOM and crop residues and the priming effect, an agricultural soil from the North Region of Cameroon with or without (controls) 13 C-labeled rice straw amendment as crop residues was either subjected to five wetting-drying cycles or maintained at constant water potential after a single rewetting event. Soil samples were incubated for 70 days at 28 °C and the CO 2 and 13 CO 2 emissions and mineral N were monitored. Adding straw (+ 833 μg C g − 1 soil) increased the cumulative CO 2 emissions from the soil (+ 921 μg C-CO 2 g − 1 soil). A positive priming effect was observed (+ 92 μg C-CO 2 g − 1 soil). Only the first wetting cycle created a mineralization flush of the SOM and the straw. This flush did not recur probably because of a lack of labile SOM. However an extra addition of straw after 28 days increased CO 2 emissions but did not result in further mineralization flushes after re-wetting while SOM mineralization was not limited by N availability. We conclude that SOM depletion under Sudano-Sahelian conditions was not explained by SOM mineralization enhancement due to multiple rewetting events or to priming effect following crop residues addition. Indeed, SOM depletion could rather be explained by a high level of mineralization of both, SOM and crop residues, when the soil reached its water retention capacity.
- Published
- 2017