Impacts of organic residue management on the soil C dynamics in a tropical eucalypt plantation on a nutrient-poor sandy soil after three rotations

Epron Daniel, Mouanda Cadeau, Mareschal Louis, Koutika Lydie-Stella. 2015. Impacts of organic residue management on the soil C dynamics in a tropical eucalypt plantation on a nutrient-poor sandy soil after three rotations. Soil Biology and Biochemistry, 85 : 183-189.

https://doi.org/10.1016/j.soilbio.2015.03.010

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Quartile : Q1, Sujet : SOIL SCIENCE

Résumé : Harvest residue management is a key issue for the sustainability of short rotation plantations of fast growing tree species established on poor soils and for potential carbon (C) accretion in many soils. By measuring the C isotope composition (δ13C) of different soil organic matter fractions and microbial respiration, we examined the effects of organic residue management at harvest on soil C dynamics in a tropical eucalypt plantation established on a savannah at the end of the third rotation on three treatments repeated at each harvest. We compared plots where the standard harvesting method in Congolese commercial plantations was applied (SWH; only removing the debarked commercial-sized boles) with plots where all the aboveground biomass and the litter layer from the previous rotations were removed at harvest (R) and plots where the residues from a whole tree harvest treatment were added (double slash, DS). Organic residue removal decreased the accretion of eucalypt-derived C in coarse and fine particulate organic matter (POM) fractions and in the organo-mineral fraction, resulting in 44% less total soil C in the top soil (0–0.05 m) but did not affect the amount of savannah-derived C in any SOM fraction. In contrast, increasing the amount of harvest residue by 36% in comparison with the reference practice did not increase the amount of C stored in the soil nor the accretion of eucalypt-derived C in any soil organic matter fractions, but the amount of savannah-derived C remaining in the coarse POM fraction was higher. We concluded that carbon accretion may be limited by the low C saturation level of these sandy-structured soils but that higher rates of residue retention may reduce priming on older savannah-derived C.

Mots-clés Agrovoc : Eucalyptus, plantation forestière, rotation de coupe, déchet d'exploitation forestière, Arénosol, matière organique, litière forestière, cycle du carbone, séquestration du carbone, isotope naturel, savane, propriété physicochimique du sol, utilisation des déchets, transport des substances nutritives