title: Long-term impacts of grazing intensity on soil carbon sequestration and selected soil properties in the arid Eastern Cape, South Africa.
abstract: BACKGROUND
  Little is known about how basic soil properties respond to contrasting grazing intensities in the Karoo biome, South Africa. The aim of this study was to investigate impacts of long-term (>75 years) grazing at 1.18 heads ha(-1) (heavy; CGH), 0.78 heads ha(-1) (light; CGL), and exclosure on selected soil properties. Soil samples were collected to a depth of 60 cm from the long-term experimental site of Grootfontein Agricultural Development Institute, Eastern Cape. The samples were analyzed for C, N, bulk density and infiltration rate, among others.
  
  
  RESULTS
  Generally, heavy and light grazing reduced soil N storage by 27.5% and 22.6%, respectively, compared with the exclosure. Animal exclusion improved water infiltration rate and C stocks significantly (P < 0.05), which was 0.128, 0.097, and 0.093 Mg ha(-1) yr(-1) for exclosure, CGL and CGH, respectively. Soil penetration resistance was higher for grazing treatments in the top 3-7 cm soil layer but for exclosure at the top 1 cm soil surface.
  
  
  CONCLUSIONS
  Although livestock exclusion has the potential to improve C sequestration, a sufficient resting period for 1-2 years followed by three consecutive grazing years at light stocking rate would be ideal for sustainable livestock production in this arid region of South Africa.
authors.affiliation: Department of Animal and Wildlife Sciences, University of Pretoria, Pretoria, South Africa.
authors.forename: Deribe G
authors.initials: DG
authors.lastname: Talore
authors.affiliation: Department of Plant Production and Soil Sciences, University of Pretoria, Pretoria, South Africa.
authors.forename: Eyob H
authors.initials: EH
authors.lastname: Tesfamariam
authors.affiliation: Department of Animal and Wildlife Sciences, University of Pretoria, Pretoria, South Africa.
authors.forename: Abubeker
authors.initials: A
authors.lastname: Hassen
authors.affiliation: Department of Animal and Range Science, Grootfontein Agricultural Research Institute, Eastern Cape, South Africa.
authors.forename: J C O
authors.initials: JC
authors.lastname: Du Toit
authors.affiliation: Grassland Ecosystem Research, INRA, Paris, France.
authors.forename: Katja
authors.initials: K
authors.lastname: Klampp
authors.affiliation: French National Institute for Agronomic Research, INRA, Paris, France.
authors.forename: Soussana
authors.initials: S
authors.lastname: Jean-Francois
mesh_terms: D000818:Animals; D002244:Carbon / Q000737:chemistry*; D017753:Ecosystem; D005247:Feeding Behavior; D058751:Livestock / Q000502:physiology*; D009584:Nitrogen / Q000737:chemistry; D010944:Plants / Q000145:classification; D012987:Soil / Q000737:chemistry*; D013019:South Africa; D013997:Time Factors
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: arid lands; carbon; continuous grazing; exclosure; nitrogen; soil properties