134-10
Impacts Of Management Intensification On Soil Carbon Stocks In Subtropical Grasslands.

Monday, November 4, 2013: 3:30 PM
Tampa Convention Center, Room 1 and 2, First Floor

Julius B. Adewopo1, Maria Lucia A. Silveira2, Stefan Gerber3, Lynn E. Sollenberger4, Tim Martin5 and Sutie Xu1, (1)Soil and Water Science Department, University of Florida, Gainesville, FL
(2)UF/IFAS Range Cattle Research and Education Center, Ona, FL
(3)Soil and Water Science, University of Florida, Gainesville, FL
(4)Agronomy Department, University of Florida, Gainesville, FL
(5)School for Forest Resources and Conservation, University of Florida, Gainesville, FL
Soil acts as sink and source of atmospheric carbon (C). Assessment of the long-term impacts of land-use change on soil C stocks is crucial for the sustainability of managed grasslands and for climate change mitigation. This study was conducted to assess the long-term (> 20 yr) impacts of grassland intensification on above- and below-ground C stocks in subtropical ecosystems. The experimental sites consisted of three replicated grassland ecosystems: native-rangeland (least-managed), slash-pine-bahiagrass silvopasture (moderately-managed), and improved bahiagrass pasture (intensively-managed). Soil cores (0-30cm depth) were collected within six adjacent experimental fields (3 ecological units × 2 replicates) to assess C stocks. Root and above-ground biomass were also quantified. Result shows that grassland intensification increased soil C stocks. Improved pasture and silvopasture contained greater soil C (62 and 69 Mg/ha, respectively) than the native rangeland (41 Mg/ha). Root biomass C in native rangeland and improved pasture was comparable (24 and 19 Mg/ha, respectively), but lower in silvopasture (15 Mg/ha). However, above-ground biomass C was greater in silvopasture compared to native rangeland (59 vs. 4.2 Mg/ha), but lower in improved pasture (2.1 Mg/ha). Particulate organic C was greater in improved pasture compared to native rangeland (34 vs. 21 Mg/ha, respectively) but did not differ from silvopasture (27 Mg/ha). Silvopastures exhibited greater amounts of stable mineral-associated C (42 Mg/ha) compared to native rangeland (20 Mg/ha) or improved pasture (28 Mg/ha). Our findings indicate that intensification of grasslands can increase soil C sequestration in the long-term, and can provide additional benefit in above-ground biomass C sequestration.
See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Soil Fertility and Plant Nutrition Division and Nutrient Management and Soil and Plant Analysis Division Graduate Student Oral Competition - General Nutrient Management (PhD degree)

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