@article{fdi:010062609,
  title = {{L}and degradation impact on soil organic carbon and nitrogen stocks of sub-tropical humid grasslands in {S}outh {A}frica},
  author = {{D}lamini, {P}. and {C}hivenge, {P}. and {M}anson, {A}. and {C}haplot, {V}incent},
  editor = {},
  language = {{ENG}},
  abstract = {{L}and degradation is recognized as a main environmental problem that adversely depletes soil organic carbon ({SOC}) and nitrogen ({SON}) stocks, which in turn directly affects soils, their fertility, productivity and overall quality. {W}hile it is expanding worldwide at rapid pace, quantitative information on the impact of land degradation on the depletion of {SOC} and {SON} stocks remains largely unavailable, limiting the ability to predict the impacts of land management on the {C} losses to the atmosphere and associated global warming. {T}he main objective of this study was to evaluate the consequences of a decrease in grass aerial cover on {SOC} and {SON} stocks. {A} degraded grassland showing an aerial cover gradient from 100% ({C}ov100, corresponding to a non-degraded grassland) to 50-75% ({C}ov75), 25-50% ({C}ov50) and 0-5% ({C}ov5, corresponding to a heavily degraded grassland), was selected in {S}outh {A}frica. {S}oil samples were collected in the 0.05 m soil layer at 48 locations along the aerial cover gradient and were subsequently separated into the clay + silt (2-20 mu m) and sand (20-2000 mu m) fractions, prior to total {C} and {N} analysis (n = 288). {T}he decline in grass aerial cover from 100% to 0-5% had a significant ({P} < 0.05) impact on {SOC} and {SON} stocks, with losses by as much as 1.25 kg m(-2) for {SOC} and 0.074 kg m(-2) for {SON}, which corresponded to depletion rates of 89 and 76%, respectively. {F}urthermore, both the {C}:{N} ratio and the proportion of {SOC} and {SON} in the silt + clay fraction declined with grass aerial cover, which was indicative of a preferential loss of not easily decomposable organic matter. {T}he staggering decline in {SOC} and {SON} stocks raises concerns about the ability of these acidic sandy loam soils to sustain their main ecosystem functions. {T}he associated decrease in chemical elements (e.g., {C}a by a maximum of 67%; {M}n, 77%; {C}u, 66%; and {Z}n, 82%) was finally used to discuss the mechanisms at stake in land degradation and the associated stock depletion of {SOC} and {SON} stocks, a prerequisite to land rehabilitation and stock replenishment.},
  keywords = {{C}arbon cycle ; {P}asture ; {R}angeland ; {C}limate change ; {E}cosystems ; {AFRIQUE} {DU} {SUD}},
  booktitle = {},
  journal = {{G}eoderma},
  volume = {235},
  numero = {},
  pages = {372--381},
  ISSN = {0016-7061},
  year = {2014},
  DOI = {10.1016/j.geoderma.2014.07.016},
  URL = {https://www.documentation.ird.fr/hor/fdi:010062609},
}