Grassland Management and Conversion into Grassland: Effects on Soil Carbon

Ecological Applications 11(2): 343-355 (2001)

R. Conant, K. Paustian, and E. Elliot
Natural Resource Ecology Laboratory
Colorada State University
Fort Collins, Colorado, USA





Sponsor: US Environmental Protection Agency, Ruminant Livestock Efficiency Program

Abstract

Grasslands are heavily relied upon for food and forage production. A key component for sustaining production in grassland ecosystems is the maintenance of soil organic matter (SOM), which can be strongly influenced by management. Many management techniques intended to increase forage production may potentially increase SOM, thus sequestering atmospheric carbon (C). Further, conversion from either cultivation or native vegetation into grassland could also sequester atmospheric carbon. We reviewed studies examining the influence of improved grassland management practices and conversion into grasslands on soil C worldwide to assess the potential for C sequestration. Results from 115 studies containing over 300 data points were analyzed. Management improvements included fertilization (39%), improved grazing management (24%), conversion from cultivation (15%) and native vegetation (15%), sowing of legumes (4%) and grasses (2%), earthworm introduction (1%), and irrigation (1%). Soil C content and concentration increased with improved management in 74% of the studies, and mean soil C increased with all types of improvement. Carbon sequestration rates were highest during the first 40 yr after treatments began and tended to be greatest in the top 10 cm of soil. Impacts were greater in woodland and grassland biomes than in forest, desert, rain forest, or shrubland biomes. Conversion from cultivation, the introduction of earthworms, and irrigation resulted in the largest increases. Rates of C sequestration by type of improvement ranged from 0.11 to 3.04 Mg C·ha^-1 yr^-1, with a mean of 0.54 Mg C·ha ^-1·yr^-1, and were highly influenced by biome type and climate. We conclude that grasslands can act as a significant carbon sink with the implementation of improved management.

The data for this study may be accessed in ESA's Electronic Data Archive: Ecological Archives A011-005.

For related work, see

• Conant and Paustian (2002). Potential soil carbon sequestration in overgrazed grassland ecosystems. Global Biogeochemical Cycles 16(4): 1143.
• Contant et al. (2003) Spatial variability of soil carbon in forested and cultivated sites: Implications for change detection. Journal of Environmental Quality 32(1): 278-286.
• Conant and Paustian (2002). Spatial variability of soil organic carbon in grasslands: implications for detecting change at different scales. Environmental Pollution 116: S127-S135 Suppl. 1.

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