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The Importance of Rock Fragment Density for the Calculation of Soil Bulk Density and Soil Organic Carbon Stocks
Author(s) -
Mehler Knut,
Schöning Ingo,
Berli Markus
Publication year - 2014
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2013.11.0480
Subject(s) - subsoil , soil science , soil water , soil carbon , bulk density , volume (thermodynamics) , environmental science , radio frequency , mineralogy , analytical chemistry (journal) , geology , chemistry , environmental chemistry , physics , thermodynamics , computer science , telecommunications
To determine the bulk density of the fine fraction (BD FF ) and soil organic carbon (SOC) stocks from core samples of a known volume, the volume of discarded rock fragments (RFs) has to be known. Measuring the RF density (ρ RF ) is labor intensive and time consuming, so the volume of RFs is often estimated based on measured RF mass and constant values for ρ RF . In this study, we determined the ρ RF of 87 soils in Germany and showed how different ρ RF of limestone affected the calculation of BD FF and SOC stocks. For limestone, the measured ρ RF in our soils was lower (2.49 ± 0.14 g cm ‐3 ) than a constant value of 2.70 g cm ‐3 . The average difference in BD FF and SOC was 2.30 and 2.35%, respectively, which was lower than errors that arose from sampling or analytical techniques. However, differences in the BD FF and SOC stocks can be as high as 37% when ρ RF is below 2.20 g cm ‐3 and there is an increase in the subsoil RF content of up to 70%. Therefore, accurately determining the ρ RF , at least in the subsoil, is recommended when RFs dominate the total volume of the sample to reduce potential measurement errors. The necessity of using the actual ρ RF instead of using a constant value depends on the variation in ρ RF , the RF content, and the intended accuracy of the BD FF and SOC stock estimation.