Publications des scientifiques de l'IRD

Yemadje P. L., Chevallier Tiphaine, Guibert H., Bertrand I., Bernoux Martial. (2017). Wetting-drying cycles do not increase organic carbon and nitrogen mineralization in soils with straw amendment. Geoderma, 304 (SI), p. 68-75. ISSN 0016-7061.

Titre du document
Wetting-drying cycles do not increase organic carbon and nitrogen mineralization in soils with straw amendment
Année de publication
2017
Type de document
Article référencé dans le Web of Science WOS:000407539400009
Auteurs
Yemadje P. L., Chevallier Tiphaine, Guibert H., Bertrand I., Bernoux Martial
Source
Geoderma, 2017, 304 (SI), p. 68-75 ISSN 0016-7061
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) C-13-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 degrees C and the CO2 and (CO2)-C-13 emissions and mineral N were monitored. Adding straw (+ 833 mu g C g(-1) soil) increased the cumulative CO2 emissions from the soil (+921 mu g C-CO2 g(-1-) soil). A positive priming effect was observed (+92 mu g C-CO2 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 CO2 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.
Plan de classement
Pédologie [068]
Description Géographique
CAMEROUN ; ZONE SOUDANIENNE ; ZONE SAHELIENNE
Localisation
Fonds IRD [F B010070970]
Identifiant IRD
fdi:010070970
Contact