Author(s): Gusman Catari* and Carlos Rivera

Affiliation: *National Autonomous University of Honduras, Centro Universitario Regional del Litoral Atlántico (CURLA), Soil Department, Colonia El Búfalo, La Ceiba, Honduras

Abstract: Soil organic carbon (SOC) is important in the carbon cycle and studies in the field are gaining relevance because of its relation to global climate change. In this paper, we report a study of SOC stock (0-200 cm) from a 50 years old secondary forest and a pasture under inceptisols in a floodplain in the tropical humid Caribbean coast of Honduras. Samples were collected at the depths 0-20, 20-40, 40-80, 80-120, 120-160, and 160-200 cm. Total SOC stocks were 89.2±10.9 Mg ha⁻¹, and 72.5±10.0 Mg ha⁻¹ for the secondary forest and pasture respectively. The estimated annual increase of SOC stock in the forest is 0.34 Mg C ha^-1 year^-1. SOC stock values were 50.3% and 47.9% of the total (0-200 cm) in the 0-20 cm layer for forest and pasture respectively. SOC distribution at a depth of 0-20 cm were 21.26 g kg^-1 and 12.09 g kg^-1 for forest and pasture respectively. Soil texture at the 0-20 cm depth were clay loam, and sandy clay loam, in the forest and pasture respectively. SOC stock in these ecosystems would be reduced if they were converted back to conventional agriculture, particularly in the forest. The forest had higher SOC values because of higher litter input as compared to the pasture, particularly in the upper soil layers, at deeper layers there are no significant differences (p <0.05) and SOC values are low. Compared to most other studies in tropical regions, SOC stock in our study were lower in both ecosystems, this may be due to high precipitation (ca. 3200 mm year^-1) and high temperatures, rate of decomposition of litter input, general low clay content, and possibly priming effects which we have not addressed. More studies on the SOC stock in Central America with a similar climate are needed to improve our understanding of SOC dynamics and help reducing uncertainty in SOC models.

DOI: 10.22271/2582-3744.2021.jun.52

Pages: 52-61 | Views: 850 | Downloads: 566

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