Loss-on-Ignition Method to Assess Soil Organic Carbon in Calcareous Everglades Wetlands

• Published in: Communications in soil science and plant analysis Vol. 39; no. 19-20; pp. 3074 - 3083
• Main Authors: Wright, Alan L, Wang, Yu, Reddy, K.R
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group, LLC 01-11-2008; Taylor & Francis
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; calcareous soils; Calcium; calcium carbonate; calcium carbonates; Carbon; carbon-nitrogen-sulfur analysis; Chemical, physicochemical, biochemical and biological properties; CNS analysis; depth; Everglades; Fundamental and applied biological sciences. Psychology; loss on ignition; methodology; Organic carbon; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Q1; Q3; Soil; soil analysis; soil organic carbon; Soil science; total C; USA, Florida, Everglades; wetland soils; Wetlands; Everglades; Florida; United States; North America; America; Organic carbon; Combustion residue; Soils; wetlands; Everglades; loss on ignition; Limestone; total C; Wetland
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1080/00103620802432931

Measurement of soil carbon (C) is important for determining the effects of Everglades restoration projects on C cycling and transformations. Accurate measurement of soil organic C by automated carbon-nitrogen-sulfur (CNS) analysis may be confounded by the presence of calcium carbonate (CaCO3) in Everglades wetlands. The objectives of this study were to compare a loss-on-ignition (LOI) method with CNS analysis for assessment of soil C across a diverse group of calcareous Everglades wetlands. More than 3168 samples were taken from three soil depths (floc, 0-10, 10-30 cm) in 14 wetlands and analyzed for LOI, total C, and total calcium (Ca). The LOI method compared favorably to CNS analysis for LOI contents ranging from 0 to 1000 g kg-1 and for soil total Ca levels from 0 to 500 g Ca kg-1. For all wetlands and soil depths, LOI was significantly related to total C (r2 = 0.957). However, LOI was a better predictor of total C when LOI exceeded 400 g kg-1 because of less interference by CaCO3. Total C measurement by CNS analysis was problematic in soils with high total Ca and low LOI, as the presence of CaCO3 confounded C analysis for LOI less than 400 g kg-1. Inclusion of total Ca in regression models with LOI significantly improved the prediction of total C. Estimates of total organic C by CNS analysis were obtained by accounting for C associated with CaCO3 by calculation, with results being similar to total organic C values obtained from LOI analysis. The proportion of C in organic matter measured by the LOI method (51%) was accurate and applicable across wetlands, soil depths, and total Ca levels; thus LOI was a suitable indicator of total organic C in Everglades wetlands.