S06-0136.indd



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Category: Ecological Research

Title: Estimating organic carbon from loss-on-ignition in northern Arizona forest soils

Author: * Abella, S.R., Zimmer, B.W.

Subject: Carbon, Soil

Abstract: Many studies in ecology, soil science, and global climate change require accurate estimates of soil organic C (SOC). When calibrated with direct SOC determinations, loss-on-ignition (LOI) has been proposed as a rapid, inexpensive, and accurate method for estimating SOC. We collected 0- to 15- and 15- to 50-cm mineral soil samples from 102 plots within a 110 000-ha ponderosa pine (Pinus ponderosa P. (and) C. Lawson) landscape to develop regression equations between LOI and SOC measured with an elemental C analyzer. We tested nine LOI temperatureduration combinations ranging from 300 to 600C and 2 to 6 h to discern optimal combinations for estimating SOC, used the optimal combination to develop regressions for 100 samples each of 0- to 15- and 15- to 50-cm depths, and assessed whether stratifying samples into ecosystem types improved LOISOC equations. Pearson r2 values between LOI and SOC did not exceed 0.74 for any LOI temperatureduration combination. These values showed no consistent trend to change with increasing duration, but tended to be slightly higher at the lowest temperature (300C). Multiple regressions, including LOI and clay concentration, explained only 78 (015 cm) and 64(percent) (1550 cm) of the variation in SOC. Relationships between LOI and SOC found in this study are among the weakest reported in the soil literature, and it remains unclear precisely why observed relationships were weak. Our results suggest that LOI may be useful for roughly estimating SOC in this region, but other methods or modifications to LOI are needed when more accurate SOC measurements are required.

Date: 2007

Type: Journal

Source: Soil Science Society of America Journal

Identifier: 71(2):545-550

Publisher: Soil Science Society of America

Format: PDF

Language: English