Land–Use Changes Influencing C Sequestration and Quality in Topsoil and Subsoil

Agronomy

Benjapon Kunlanit¹  Somchai Butnan²  Patma Vityakon² 

[1] Department of Agricultural Technology, Faculty of Technology, Maha Sarakham University, Maha Sarakham 44150, Thailand;Soil Organic Matter Management Research Group, Khon Kaen University, Khon Kaen 40002, Thailand;

关键词: cassava;    dipterocarp forest;    humic acid;    E4:E6 ratio;    soil depth;    paddy rice;   

DOI  :  10.3390/agronomy9090520

来源: DOAJ

【 摘 要 】

Soil capacity as a major carbon (C) sink is influenced by land use. Estimates of soil organic carbon (SOC) sequestration have mostly focused on topsoils [0−30 cm official Intergovernmental Panel on Climate Change (IPCC) soil depth]. We investigated SOC stocks and their quality as influenced by land-use changes. Soil samples were collected from five soil depths down to 100 cm of three adjacent fields each representing a different land use—forest, cassava, and rice paddy—in Northeast Thailand. Sequestration of SOC in topsoils under all land uses was higher, as indicated by SOC stocks (59.0−82.0 Mg ha⁻¹) than subsoils (30−100 cm) (27.0−33.0 Mg ha⁻¹). The soil profile (0−100 cm) of the forest had higher stocks of SOC and humic acid (115.0 and 6.8 Mg ha⁻¹, respectively) than those of cultivated land uses [paddy (100.0 and 4.8 Mg ha⁻¹, respectively) and cassava (87.0 and 2.3 Mg ha⁻¹, respectively)], which accounted for an average 30% increase in SOC sequestration over those with only topsoil. Topsoils of the forest had higher humic acid content but narrower E4:E6 ratio [the ratio of absorbances at 465 nm (E4) and at 665 nm (E6)] of humic acids (2.8), indicating a higher degree of humification and stabilization than the cultivated soils (3.2−3.6). Subsoil C was higher quality, as indicated by the lower E4:E6 ratio of humic acids than topsoils in all land uses.

【 授权许可】

Unknown