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The Effect of Jatropha curcas L. Leaf Litter Decomposition on Soil Carbon and Nitrogen Status and Bacterial Community Structure (senegal


Affiliations
1 Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal
2 Ecole Nationale Supérieure d’Agriculture, Thiès, Senegal
3 Département de Biologie Animale, Université Cheikh Anta Diop Dakar, Senegal
4 Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal
 

The cultivation of Jatropha curcas L. as a biodiesel feedstock has been encouraged in Senegal to reduce dependence on fossil fuels and mitigate the effects of climate change. J. curcasis is a poisonous plant which sheds its leaves during the dry season. Although the leaves are toxic for animals, they can help to recycle soil organic matter. This study set out to determine the effect of the decomposition dynamics of green and senescent J. curcas leaves on the soil C and N contents and on the structure of the bacterial community. Leaf litter decomposition was studied for 4 months by laboratory incubation and samples were taken at the start of incubation and at 3, 28, 56, 90 and 120 days. Green leaves had a higher N content, higher concentrations of water soluble compounds and hemicelluloses, but a lower C:N ratio and lignin content than senescent leaves regardless of the cultivar. The cultivar, the type of litter and the interaction between them, all had a significant effect on the soil N content (p2=0.995) and C:N ratio (p<0.0001, R2=0.998). However, the cultivar was the only factor that affected the leaf C content (p<0.05, R2=0.624). The initial N content explained the N-NH4 + mineralization at the start of decomposition and the initial lignin content explained the N-NH4 + mineralization at later stages of decomposition. The recalcitrant C content in the green leaves was estimated as being between 70.01 and 73.33% of the total C content and between 72 and 77.33% in senescent leaves. This suggests that Jatropha litter may contribute significantly to soil C sequestration. The results indicate that the soil had higher bacterial diversity in the later stages of litter decomposition, for both types of litter and all cultivars.

Keywords

Jatropha curcas L., Leaf Litter, Nitrogen Mineralization, Carbon Mineralization, Bacterial Community, Polymerase Chain Reaction Denaturing Gradient Gel Electrophoresis (PCR-DGGE), Senegal.
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  • The Effect of Jatropha curcas L. Leaf Litter Decomposition on Soil Carbon and Nitrogen Status and Bacterial Community Structure (senegal

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Authors

Tidiane Dieye
Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal
Komi Assigbetse
Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal
Ibrahima Diedhiou
Ecole Nationale Supérieure d’Agriculture, Thiès, Senegal
Mbacke Sembene
Département de Biologie Animale, Université Cheikh Anta Diop Dakar, Senegal
Amadou Lamine Dieng
Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal
Mariama Gueye
Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal
Dominique Masse
Centre de Recherche IRD-ISRA de Bel-Air, UMR 210 Eco&Sols LMI IESOL, Laboratoire d’Ecologie Microbienne des Sols et Agrosystèmes Tropicaux, B.P. 1386 CP 18524 Dakar, Senegal

Abstract


The cultivation of Jatropha curcas L. as a biodiesel feedstock has been encouraged in Senegal to reduce dependence on fossil fuels and mitigate the effects of climate change. J. curcasis is a poisonous plant which sheds its leaves during the dry season. Although the leaves are toxic for animals, they can help to recycle soil organic matter. This study set out to determine the effect of the decomposition dynamics of green and senescent J. curcas leaves on the soil C and N contents and on the structure of the bacterial community. Leaf litter decomposition was studied for 4 months by laboratory incubation and samples were taken at the start of incubation and at 3, 28, 56, 90 and 120 days. Green leaves had a higher N content, higher concentrations of water soluble compounds and hemicelluloses, but a lower C:N ratio and lignin content than senescent leaves regardless of the cultivar. The cultivar, the type of litter and the interaction between them, all had a significant effect on the soil N content (p2=0.995) and C:N ratio (p<0.0001, R2=0.998). However, the cultivar was the only factor that affected the leaf C content (p<0.05, R2=0.624). The initial N content explained the N-NH4 + mineralization at the start of decomposition and the initial lignin content explained the N-NH4 + mineralization at later stages of decomposition. The recalcitrant C content in the green leaves was estimated as being between 70.01 and 73.33% of the total C content and between 72 and 77.33% in senescent leaves. This suggests that Jatropha litter may contribute significantly to soil C sequestration. The results indicate that the soil had higher bacterial diversity in the later stages of litter decomposition, for both types of litter and all cultivars.

Keywords


Jatropha curcas L., Leaf Litter, Nitrogen Mineralization, Carbon Mineralization, Bacterial Community, Polymerase Chain Reaction Denaturing Gradient Gel Electrophoresis (PCR-DGGE), Senegal.