Identifier

etd-04112014-144547

Degree

Master of Science (MS)

Department

Plant, Environmental Management and Soil Sciences

Document Type

Thesis

Abstract

The soil organic carbon (SOC) pool is an important component of the global carbon budget. Agricultural systems in particular have been identified as an area in which SOC may be increased appreciably when managed for carbon sequestration. In the southern climate region of the United States, potential rates of carbon sequestration in soils are largely unquantified. The aim of this study was to quantify SOC and its spatial variability under two long-term residue management systems, burn and no-burn, for sugarcane (Saccharum Spp. Hyb.). Soil cores to a depth of 1 m were collected using a Giddings probe. Thirty soil cores per treatment were collected along a transect with 1.8-m spacing. Parameters measured were SOC, soil nitrogen, bulk density, gravimetric water content, CEC, and pH. Comparisons between treatments were conducted using paired t-tests. Geostatistical analyses were used to investigate 2-D vertical and lateral spatial trends. In a subsequent sampling, soil cores were collected from depths up to 2.7 m, and SOC, soil nitrogen, and gravimetric water content were measured. Differences in SOC between the two treatments were significant (t = 2.35, p = 0.019) and indicated that the no-burn treatment contained more SOC than the burn treatment. Variogram models indicated that the no-burn treatment (range = 10.19 m) had higher spatial variability than the burn treatment (range = 18.95 m), and kriging illustrated that the burn treatment had a SOC content that was more evenly distributed with depth. Some 70 % of SOC was in the 20-100 cm soil depth, and the greatest differences between the treatments occurred at depths below 60 cm. Estimated carbon sequestration was 0.56 Mg/ha/yr. A major finding from this study is that soil carbon sequestration in the burn and no-burn managements was consistent with other studies in the region; however, significant quantities of SOC may be present at depths below the typical 20-cm sampling depth, and ignoring deeply distributed carbon may result in the underestimation of carbon sequestration.

Date

2014

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Selim, Magdi

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