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Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Proceedings Publication Acceptance Date: 7/14/2003 Publication Date: 7/14/2003 Citation: Torbert, H.A., Prior, S.A., and Runion, G.B. 2003. Impact of land use management decisions on C sequestration. In: Soil Management for Sustainability, International Soil Tillage Research Organization, 16th Triennial Conference Book of Abstracts, University of Queensland, Brisbane, Australia, July 14-18. p. 1253-1258. Interpretive Summary: Growing concern regarding the impact of CO2 on the atmosphere has led to scientist explore the possibility of capturing C in soil as a result of changes in land management. Generally, this requires that land be taken out of cultivated agriculture. However, one potential problem with collecting C in soil is that it may can be quickly eliminated with the return to cultivation. The objective of this study was to examine the impact of converting land back into cultivated agricultural management on soil C within two different soil types. Soil samples were collected from a sandy loam soil and a clay loam soil in central Alabama which had been under different land management systems. The management systems included locations for both soil types that were forested, and that had been managed as permanent pasture for greater than 40 years. Within the permanent pastures, locations that had been converted to continuous cultivation for 1 and 2 years were sampled. Within the sandy loam soil, land management locations which had been continuously cultivated were compared to locations that had been removed from cultivation and those that had been returned to cultivation after being fallowed for 5 years. Soil samples were analyzed for total N, total C, soil C:N ratio, and bulk density. The clay soil had higher capacity to capture C, compared to the sandy loam soil. In the clay loam soil, little differences could be observed between the forested soil and the permanent pasture, while in the sandy loam soil, large differences were observed for C between the forested and the permanent pasture sites. The results indicate that the vulnerability of soil to lose sequestered C may depend on the soil type. Clay soils, although having higher levels of C, may lose as much as 55% of its C with as little as 2 yrs of cultivation, while sandy soils may show no significant effect on C content within the same time frame. Technical Abstract: A growing body of science indicates that C can be sequestered in soil as a result of changes in land management. Generally, this requires that land be taken out of cultivated agriculture; however, it has been postulated that the gains in soil C can be quickly eliminated with the return to cultivation. The objective of this study was to examine the impact of converting land back into cultivated agricultural management on C sequestration within two different soil types. Soil samples from nine soil depth increments (0-5, 5-10, 10-15, 15-30, 30-45, 45-60, 60-75, 75-90, and 90-105 cm) were collected from a Marvyn sandy loam (fine-loamy, Kaolinitic, thermic Typic Kanhapludults) and a Hannon clay loam (fine, smectitic, thermic Chromic Hapluderts) in central Alabama, USA, which had been under different land management systems. The management systems included locations for both soil types that were forested, and that had been managed as permanent pasture for greater than 40 years. Within the permanent pastures, locations that had been converted to continuous cultivation for 1 and 2 years were sampled. Within the sandy loam soil, land management locations which had been continuously cultivated were compared to locations that had been removed from cultivation and those that had been returned to cultivation after being fallowed for 5 years. Soil samples were analyzed for total N, total C, soil C:N ratio, and bulk density. The clay soil had higher capacity to sequester C, compared to the sandy loam soil. In the clay loam soil, little differences could be observed between the forested soil and the permanent pasture, while in the sandy loam soil, large differences were observed for C between the forested and the permanent pasture sites. The results indicate that the vulnerability of soil to lose sequestered C may depend on the soil type. Clay soils, although having higher levels of C, may lose much (55%) of this with as little as 2 yrs of cultivation, while sandy soils may show no significant effect on C content within the same time frame. |
