Role of root inputs from a dinitrogen-fixing tree in soil carbon and nitrogen sequestration in a tropical agroforestry system
Jorge Sierra A D and Pekka Nygren B CA Unité Agropédoclimatique de la Zone Caraïbe, INRA Antilles-Guyane, Domaine Duclos (Prise d’eau), 97170 Petit-Bourg, Guadeloupe (French Antilles), France.
B Center for Agroforestry, University of Missouri–Columbia, 203 Natural Resources Building, Columbia, MO 65211, USA.
C Present address: Department of Forest Ecology, PO Box 27, 00014 University of Helsinki, Finland.
D Corresponding author. Email: sierra@antilles.inra.fr
Australian Journal of Soil Research 43(5) 667-675 https://doi.org/10.1071/SR04167
Submitted: 16 November 2004 Accepted: 20 April 2005 Published: 8 August 2005
Abstract
Agroforestry is often mentioned as a suitable technology for land rehabilitation in the tropics and for mitigation of climate change because this land-use favours nutrient recycling and C sequestration. The aim of this work was to estimate soil C sequestration in a 12-year-old tropical silvopastoral system composed of a legume tree (Gliricidia sepium) and a C4 fodder grass (Dichanthium aristatum), and to link it with tree root biomass and N status in the soil. The site was under cut-and-carry management, i.e. tree pruning residues and cut grass were removed from the field and fed to stabled animals elsewhere. Thus, main sources for tree C and N inputs were root activity and turnover. Organic C derived from the trees and tree root biomass were determined based on natural 13C abundance. For the 0–0.2 m soil layer, the biomass of tree roots ≤2 mm diameter was 2.4 Mg/ha when the trees were pruned every 6 months (SS6), and 0.6 Mg/ha when pruned every 2 months (SS2). Both C (R2 = 0.39, P < 0.05) and N (R2 = 0.82, P < 0.05) sequestration were correlated with tree root biomass. The trees and grass contributed 18 and 8 Mg C/ha to soil, respectively, over the 12-year experiment in SS6. The net increase of 2.5 Mg N/ha in soil, originating from the trees, contributed to the net soil C sequestration. In SS2, trees contributed 16 Mg C/ha to soil over 12 years, but grass-derived C was reduced by 2 Mg C/ha because of the small amount of grass litter. The increase of 1.7 Mg N/ha in soil, derived from the trees, was not large enough to avoid C loss in this plot. Differences in soil C and N sequestration between plots were due to differences in system management, which affected the amount and the C/N ratio of inputs and outputs.
Additional keywords: natural 13C abundance, tree pruning, Vertisol, Vertosol.
Acknowledgments
We thank Saint-Ange Sophie (Agropedoclimatic Station) for skilful technical assistance and for the management of the experimental plots since 1989; Roxane Fagan (Stable Isotope Laboratory of the Kansas State University, USA) for carrying out the mass spectrometry of 13C samples; and Alan Scaife for reviewing the English manuscript. This work was financed by funds from the University of Missouri Life Sciences Mission Enhancement Programme (PN) and the Department Environment and Agronomy of the Institut National de la Recherche Agronomique, France (JS).
Balesdent J
(1996) The significance of organic separates to carbon dynamics and its modeling in some cultivated soils. European Journal of Soil Science 47, 485–493.
Balesdent J,
Mariotti A, Guillet B
(1987) Natural 13C abundance as a tracer for studies of soil organic matter dynamics. Soil Biology and Biochemistry 19, 25–30.
| Crossref | GoogleScholarGoogle Scholar |
Bonde TA,
Christensen BT, Cerri CC
(1992) Dynamics of soil organic matter as reflected by natural 13C abundance in particle size fractions of forested and cultivated oxisols. Soil Biology and Biochemistry 24, 275–277.
| Crossref | GoogleScholarGoogle Scholar |
Del Galdo I,
Six J,
Peressotti A, Cotrufo MF
(2003) Assessing the impact of land-use change on soil C sequestration in agricultural soils by means of organic matter fractionation and stable C isotopes. Global Change Biology 9, 1204–1213.
| Crossref | GoogleScholarGoogle Scholar |
Dulormne M
(2001) Analyse de l’effet ombrage dans un système agroforestier légumineuse arbustive–herbe. PhD thesis, University Paris XI, France.
Dulormne M,
Sierra J,
Nygren P, Cruz P
(2003) Nitrogen-fixation dynamics in a cut-and-carry silvopastoral system in the subhumid conditions of Guadeloupe, French Antilles. Agroforestry Systems 59, 121–129.
| Crossref | GoogleScholarGoogle Scholar |
Eshetu Z
(2002) Historical C3–C4 vegetation pattern on forested mountain slopes: its implication for ecological rehabilitation of degraded highlands of Ethiopia by afforestation. Journal of Tropical Ecology 18, 743–758.
| Crossref | GoogleScholarGoogle Scholar |
Harris D,
Horwath WR, van Kessel C
(2001) Acid fumigation of soils to remove carbonates prior to total organic carbon or carbon-13 isotopic analysis. Soil Science Society of America Journal 65, 1853–1856.
IPCC (2000).
Izac AMN, Sanchez PA
(2001) Towards a natural resource management paradigm for international agriculture: the example of agroforestry research. Agricultural Systems 69, 5–25.
| Crossref | GoogleScholarGoogle Scholar |
Kanninen M
(2001) Silvopastoral systems and carbon sequestration: potential in Latin America. ‘Electronic conference: Potential of silvopastoral systems for the generation of environmental services’. (in Spanish). (FAO-LEAD Virtual Research and Development Centre)
http://lead-es.virtualcentre.org
Kass DCL,
Sylvester-Bradley R, Nygren P
(1997) The role of nitrogen fixation and nutrient supply in some agroforestry systems of the Americas. Soil Biology and Biochemistry 29, 775–785.
| Crossref | GoogleScholarGoogle Scholar |
Koskela J, Nygren P, Berninger F, Luukkanen O
(2000) Implications of the Kyoto Protocol for tropical forest management and land use: prospects and pitfalls. University of Helsinki Tropical Forestry Reports No.22. http://honeybee.helsinki.fi/tropic/kyoto.pdf
Leakey RRB
(1998) Agroforestry for biodiversity in farming systems. ‘The importance of biodiversity in agroecosystems’. (Eds W Collins, C Qualset)
pp. 127–145. (Lewis Publishers: New York)
Littell, RC ,
Milliken, GA ,
Stroup, WW ,
and
Wolfinger, RD (1996).
Nicolardot B,
Recous S, Mary B
(2001) Simulation of C and N mineralisation during crop residue decomposition: a simple dynamic model based on the C : N ratio of the residues. Plant and Soil 228, 83–103.
| Crossref | GoogleScholarGoogle Scholar |
Nygren P, Cruz P
(1998) Biomass allocation and nodulation of Gliricidia sepium under two cut-and-carry forage production regimes. Agroforestry Systems 41, 277–292.
| Crossref | GoogleScholarGoogle Scholar |
Nygren P,
Cruz P,
Domenach AM,
Vaillant V, Sierra J
(2000a) Influence of forage harvesting regimes on dynamics of biological dinitrogen fixation of a tropical woody legume. Tree Physiology 20, 41–48.
| PubMed |
Nygren P,
Lorenzo A, Cruz P
(2000b) Decomposition of woody legume nodules in two tree/grass associations under contrasting environmental conditions. Agroforestry Systems 48, 229–244.
| Crossref | GoogleScholarGoogle Scholar |
Paynel F,
Murray P, Cliquet JB
(2001) Root exudates: a pathway for short-term N transfer clover and ryegrass. Plant and Soil 229, 235–243.
| Crossref | GoogleScholarGoogle Scholar |
Poulton PR,
Pye E,
Hargreaves PR, Jenkinson DS
(2003) Accumulation of carbon and nitrogen by old arable land reverting to woodland. Global Change Biology 9, 942–955.
| Crossref | GoogleScholarGoogle Scholar |
Resh SC,
Binkley SC, Parrotta JA
(2002) Greater soil carbon sequestration under nitrogen-fixing trees compared with Eucalyptus species. Ecosystems 5, 217–231.
| Crossref |
Rhoades CC,
Eckert GE, Coleman DC
(1998) Effect of pasture trees on soil nitrogen and organic matter: implications for tropical montane forest restoration. Restoration Ecology 6, 262–270.
| Crossref | GoogleScholarGoogle Scholar |
Delaney M,
Hairiah K,
Purnomosidhi P, Roshetko JM
(2002) Carbon stocks in Indonesian homegarden systems: can smallholder systems be targeted for increased carbon storage? American Journal of Alternative Agriculture 17, 138–148.
| Crossref | GoogleScholarGoogle Scholar |
Sierra J,
Dulormne M, Desfontaines L
(2002) Soil nitrogen as affected by Gliricidia sepium in a silvopastoral system in Guadeloupe, French Antilles. Agroforestry Systems 54, 87–97.
| Crossref | GoogleScholarGoogle Scholar |
Simons AJ, Stewart JL
(1994) Gliricidia sepium—a multipurpose forage trees legume. ‘Forage tree legumes in tropical agriculture’. (Eds RC Gutteridge, HM Shelton)
pp. 30–48. (CAB International: Wallingford, UK)
Van Groenigen KJ,
Harris D,
Horwath WR,
Hartwig UA, Van Kessel C
(2002) Linking sequestration of 13C and 15N in aggregates in a pasture soil following 8 years of elevated atmospheric CO2. Global Change Biology 8, 1094–1108.
| Crossref | GoogleScholarGoogle Scholar |
Vitorello VA,
Cerri CC,
Andreux F,
Feller C, Victoria RL
(1989) Organic matter and natural carbon-13 distribution in forested and cultivated oxisols. Soil Science Society of America Journal 53, 773–778.
