References

Agbenin JO, Goladi JT (1997) Carbon, nitrogen and phosphorus dynamics under continuous cultivation as influenced by farmyard manure and inorganic fertilizers in the savanna region of northern Nigeria. Agriculture, Ecosystems & Environment 63, 17–24.
| CrossRef | CAS |

Akamigbo FOR, Igwe CA (1990) Morphology, geography, genesis and taxonomy of three soil series in Eastern Nigeria. Samaru Journal of Agricultural Research 7, 33–48.

Anikwe MAN (2010) Carbon storage in soils of southeastern Nigeria under different management practices. Carbon Balance and Management 5, Art. No. 5
| CrossRef |

Badejo MA (1998) Agroecological restoration of savanna ecosystems. Ecological Engineering 10, 209–219.
| CrossRef |

Barthes B, Azontonde A, Blanchart E, Girardin C, Villenave C, Oliver R, Feller C (2006) Effect of a legume cover crop on carbon storage and erosion in an Ultisol under maize cultivation in southern Benin. Soil Erosion and Carbon Dynamics 143–155.
| CAS |

Batjes NH (2001) Options for increasing carbon sequestration in West African soils: an exploratory study with special focus on Senegal. Land Degradation and Development 12, 131–142.
| CrossRef |

Belsky AJ, Mwonga SM, Amundson RG, Duxbury JM, Ali AR (1993) Comparative effects of isolated trees on their undercanopy environments in high- and low-rainfall savannas. Journal of Applied Ecology 30, 143–155.
| CrossRef |

Bird MI, Veenendaal EM, Moyo C, Lloyd J, Frost P (2000) Effect of fire and soil texture on soil carbon in a sub-humid savanna (Matopos, Zimbabwe). Geoderma 94, 71–90.
| CrossRef | CAS |

Blake GR, Hartge KH (1986). Bulk density. In ‘Methods of soil analysis. Part 1: Physical and mineralogical properties’. 2nd edn, Agronomy Monograph No. 9. (Ed. A Klute) pp. 363–382. (American Society of Agronomy: Madison WI)

FAO (2004) Biophysical aspects of carbon sequestration in drylands. In ‘Carbon sequestration in drylands’. FAO Corporate Document Repository. (Natural Resources Management and Environmental Department, FAO: Rome) http://www.fao.org/docrep/007/y5738e/y5738e08.htm

Gee GW, Bauder JW (1986) Particle size analysis. In ‘Methods of soil analysis. Part 1: Physical and mineralogical properties’. 2nd edn. Agronomy Monograph No. 9. (Ed. A Klute) pp. 91–100. (American Society of Agronomy: Madison, WI)

Gibbs HK, Brown S, Niles JO, Foley JA (2007) Monitoring and estimating tropical forest carbon stocks: making REDD a reality. Environmental Research Letters 2, 045023
| CrossRef |

Henry M, Valentini R, Bernoux M (2009) Soil carbon stocks in ecoregions of Africa. Biogeosciences Discussions 6, 797–823.
| CrossRef |

Holmes KW, Wherrett A, Keating A, Murphy DV (2011) Meeting bulk density sampling requirements efficiently to estimate soil carbon stocks. Soil Research 49, 680–695.
| CrossRef |

Igwe CA (2001) Effects of land use on some structural properties of an Ultisol in south-eastern Nigeria. International Agrophysics 15, 237–241.

Igwe CA, Zarei M, Stahr K (2009) Mineralogy and geochemical properties of some upland soils from different sedimentary formations in south-eastern Nigeria. Australian Journal of Soil Research 47, 423–432.
| CrossRef | CAS |

IPCC (2007) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment. In ‘Report of the Intergovernmental Panel on Climate Change’. (Eds S Solomon, D Qin, M Manning et al.) (Cambridge University Press: Cambridge, UK)

IUSS Working Group (2006) ‘World Reference Base for Soil Resources.’ IUSS-ISRIC-FAO. World Soil Resources Report No. 103. (FAO: Rome)

McKenzie N, Ryan P, Fogarty P, Wood J (2000) Sampling, measurement and analytical protocols for carbon estimation in soil, litter and coarse woody debris. National Carbon Accounting System Technical Report No. 14. Australian Greenhouse Office, Canberra.

McLean EO (1982) Soil pH and lime requirement. In ‘Methods of soil analysis, Part 2: Chemical and microbiological properties’. 2nd edn. Agronomy Monograph No. 9. (Eds AL Page, RH Miller, DR Keeney) pp. 199–224. (American Society of Agronomy: Madison, WI)

Nelson DW, Sommers LE (1996) Total carbon, total organic carbon, and organic matter. In ‘Methods of soil analysis. Part 3: Chemical methods’. Agronomy Monograph No. 9. (Ed. DL Sparks) pp. 961–1010. (American Society of Agronomy: Madison WI)

Obi ME (1982) Runoff and soil loss from an Oxisol in southeastern Nigeria under various management practices. Agricultural Water Management 5, 193–203.
| CrossRef |

Obi ME (1999) The physical and chemical responses of a degraded sandy clay loam soil to cover crops in southern Nigeria. Plant and Soil 211, 165–172.
| CrossRef | CAS |

Pieri C (1992) ‘Fertility of soils: A future for farming in the West African savannah.’ Springer Series in Physical Environment. (Springer-Verlag: Berlin)

Raji BA, Ogunwole JO (2006) Potential of soil carbon sequestration under various landuse in the subhumid and semiarid savanna of Nigeria: lessons from long-term experiments. International Journal of Soil Sciences 1, 33–43.
| CrossRef | CAS |

Ravilious C, Kapos V, Osti M, Bertzky M, Bayliss JL, Dahiru S, Dickson B (2010) Carbon, biodiversity and ecosystem services: Exploring co-benefits. Nigeria: Preliminary results. (UNEP-WCMC: Cambridge, UK) http://www.unep-wcmc.org/climate/publications.aspx

Rhoades JD (1982) Cation exchange capacity. In ‘Methods of soil analysis. Part 2: Chemical and microbial properties’. Agronomy Monograph No. 9. (Eds AL Page, RH Miller, DR Keeney) pp. 149–157. (American Society of Agronomy: Madison WI)

Richards AE, Dalal RC, Schmidt S (2009) Carbon storage in a Ferrosol under subtropical rainforest, tree plantations, and pasture is linked to soil aggregation. Australian Journal of Soil Research 47, 341–350.
| CrossRef | CAS |

Snyman HA (2003) Short-term response of rangeland following an unplanned fire in terms of soil characteristics in a semi-arid climate of South Africa. Journal of Arid Environments 55, 160–180.
| CrossRef |

Soil Survey Staff (2006) ‘Keys to Soil Taxonomy.’ 10th edn (United States Department of Agriculture, Natural Resources Conservation Services: Washington, DC)

Syswerda SP, Corbin AT, Mokma DL, Kravchenko AN, Robertson GP (2011) Agricultural management and soil carbon storage in surface vs. deep layers. Soil Science Society of America Journal 75, 92–101.
| CrossRef | CAS |

Takahashi M, Ishizuka S, Ugawa S, Sakai Y, Sakai H, Ono K, Hashimoto S, Matsuura Y, Morisada K (2010) Carbon stock in litter, deadwood and soil in Japan’s forest sector and its comparison with carbon stock in agricultural soils. Soil Science and Plant Nutrition 56, 19–30.
| CrossRef | CAS |

Tiessen H, Feller C, Sampaio EVSB, Garin P (1998) Carbon sequestration and turnover in semiarid savannas and dry forest. Climatic Change 40, 105–117.
| CrossRef | CAS |

Vågen TG, Lal R, Singh BR (2005) Soil carbon sequestration in sub-Saharan Africa: a review. Land Degradation and Development 16, 53–71.
| CrossRef |

Veldkamp E, Becker A, Schwendenmann L, Clark DA, Schulte-Bisping H (2003) Substantial labile carbon stocks and microbial activity in deeply weathered soils below a tropical wet forest. Global Change Biology 9, 1171–1184.
| CrossRef |

Yonekura Y, Ohta S, Kiyono Y, Aksa D, Morisada K, Tanaka N, Kanzaki M (2010) Changes in soil carbon stock after deforestation and subsequent establishment of “Imperata” grassland in the Asian humid tropics. Plant and Soil 329, 495–507.
| CrossRef | CAS |

Young R, Wilson BR, Mcleod M, Alston C (2005) Carbon storage in the soils and vegetation of contrasting land uses in northern New South Wales, Australia. Australian Journal of Soil Research 43, 21–31.
| CrossRef | CAS |